- α-Halo Ketone for Polyhedral Perovskite Nanocrystals: Evolutions, Shape Conversions, Ligand Chemistry, and Self-Assembly
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Bright lead halide perovskite nanocrystals, which have been extensively studied in the past 5 years, are mostly confined to a six faceted hexahedron (cube/platelet) shape. With variations of ligand, precursor, reaction temperature, and surface modification, their brightness has been enhanced and phase became stable, but ultimate nanocrystals still retained the hexahedron cube or platelet shape in most of the hot injection reactions. In contrast, by exploration of α-halo ketone in amine as a halide precursor, different shaped nanocrystals without compromising the photoluminescence quantum yield (PLQY) are reported. Confining to orthorhombic CsPbBr3, the obtained nanocrystals are stabilized by 12 facets ({200}, {020}, {112}) and led to 12 faceted rhombic dodecahedrons. These facets are absolutely different from six ({110}, {002}) equivalent facets of widely reported orthorhombic cube shaped CsPbBr3 nanocrystals. These also retained the colloidal and phase stability, as well as showed near unity PLQY. With further annealing, these are transformed to 26 faceted rhombicuboctahedrons by dissolving all their vertices. Importantly, these 12 faceted nanocrystals showed wide area self-assembly in most of the reactions. It has also been concluded that primary ammonium ions led to six faceted nanocrystals, but tertiary ammonium ions obtained in this case stabilized different group of facets. While perovskite nanocrystals were broadly confined to only nanocubes, these new nanocrystals with intense emission would certainly provide a new avenue for continuing their further research.
- Bera, Suman,Behera, Rakesh Kumar,Pradhan, Narayan
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- Tunable Hybrid Fano Resonances in Halide Perovskite Nanoparticles
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Halide perovskites are known to support excitons at room temperatures with high quantum yield of luminescence that make them attractive for all-dielectric resonant nanophotonics and meta-optics. Here we report the observation of broadly tunable Fano resonances in halide perovskite nanoparticles originating from the coupling of excitons to the Mie resonances excited in the nanoparticles. Signatures of the photon-exciton ( hybrid ) Fano resonances are observed in dark-field spectra of isolated nanoparticles, and also in the extinction spectra of aperiodic lattices of such nanoparticles. In the latter case, chemical tunability of the exciton resonance allows reversible tuning of the Fano resonance across the 100 nm bandwidth in the visible frequency range, providing a novel approach to control optical properties of perovskite nanostructures. The proposed method of chemical tuning paves the way to an efficient control of emission properties of on-chip-integrated light-emitting nanoantennas.
- Tiguntseva, Ekaterina Y.,Baranov, Denis G.,Pushkarev, Anatoly P.,Munkhbat, Battulga,Komissarenko, Filipp,Franckevi?ius, Marius,Zakhidov, Anvar A.,Shegai, Timur,Kivshar, Yuri S.,Makarov, Sergey V.
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- Highly Photoluminescent CsPbBr3/CsPb2Br5NCs@TEOS Nanocomposite in Light-Emitting Diodes
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All-inorganic halide perovskite (CsPb2Br5) nanocrystals (NCs) have received widespread attention owing to their unique photoelectric properties. This work reports a novel strategy to control the phase transition from CsPbBr3 to CsPb2Br5 and investigates the effects of different treatment times and treatment temperatures on perovskite NCs formation. By controlling the volume of tetraethoxysilane (TEOS) added, the formation of different phases of perovskite powder can be well controlled. In addition, a white light-emitting diode (WLED) device is designed by coupling the CsPbBr3/CsPbBr3-CsPb2Br5 NCs@TEOS nanocomposite and CaAlSiN3:Eu2+ commercial phosphor with a 460 nm InGaN blue chip, exhibiting a high luminous efficiency of 57.65 lm/W, color rendering index (CRI) of 91, and a low CCT of 5334 K. The CIE chromaticity coordinates are (0.3363, 0.3419). This work provides a new strategy for the synthesis of CsPbBr3/CsPbBr3-CsPb2Br5 NCs@TEOS nanocomposite, which can be applied to the field of WLEDs and display devices.
- Zhou, Yufeng,Yu, Yanxia,Zhang, Yaqian,Liu, Xiaodong,Yang, Haisheng,Liang, Xiaojuan,Xia, Wei,Xiang, Weidong
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- Photoinduced Anion Exchange in Cesium Lead Halide Perovskite Nanocrystals
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Cesium lead halide (CsPbX3) perovskite nanocrystals (NCs) possess the unique capability of post-synthesis anion exchange providing facile tunability of the optical properties, which is usually achieved by mixing NCs with reactive anion precursors. In this work, we show that the controllable anion exchange can be achieved in a dihalomethane solution of CsPbX3 NC in the absence of any spontaneously reacting anion source using photoexcitation of CsPbX3 NCs as the triggering mechanism for the halide ion exchange. The reaction begins with the photoinduced electron transfer from CsPbX3 NCs to dihalomethane solvent molecules producing halide ions via reductive dissociation, which is followed by anion exchange. The reaction proceeds only in the presence of excitation light and the rate and extent of reaction can be controlled by varying the light intensity. Furthermore, the asymptotic extent of reaction under continuous excitation can be controlled by varying the wavelength of light that self-limits the reaction when light becomes off-resonance with the absorption of NCs. The light-controlled anion exchange demonstrated here can be utilized to pattern the post-synthesis chemical transformation of CsPbX3 NCs, not readily achievable using typical methods of anion exchange.
- Parobek, David,Dong, Yitong,Qiao, Tian,Rossi, Daniel,Son, Dong Hee
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- Templated-Assembly of CsPbBr3 Perovskite Nanocrystals into 2D Photonic Supercrystals with Amplified Spontaneous Emission
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Perovskite nanocrystals (NCs) have revolutionized optoelectronic devices because of their versatile optical properties. However, controlling and extending these functionalities often requires a light-management strategy involving additional processing steps. Herein, we introduce a simple approach to shape perovskite nanocrystals (NC) into photonic architectures that provide light management by directly shaping the active material. Pre-patterned polydimethylsiloxane (PDMS) templates are used for the template-induced self-assembly of 10 nm CsPbBr3 perovskite NC colloids into large area (1 cm2) 2D photonic crystals with tunable lattice spacing, ranging from 400 nm up to several microns. The photonic crystal arrangement facilitates efficient light coupling to the nanocrystal layer, thereby increasing the electric field intensity within the perovskite film. As a result, CsPbBr3 2D photonic crystals show amplified spontaneous emission (ASE) under lower optical excitation fluences in the near-IR, in contrast to equivalent flat NC films prepared using the same colloidal ink. This improvement is attributed to the enhanced multi-photon absorption caused by light trapping in the photonic crystal.
- D?blinger, Markus,Feil, Maximilian W.,Feldmann, Jochen,Garcia-Pomar, Juan Luis,Huang, He,Liz-Marzán, Luis M,Manzi, Aurora,Mihi, Agustín,Polavarapu, Lakshminarayana,Vila-Liarte, David
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- CsPbBr3 nanocrystal saturable absorber for mode-locking ytterbium fiber laser
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Cesium lead halide perovskite nanocrystals (CsPbX3, X = Cl, Br, I) have been reported as efficient light-harvesting and light-emitting semiconductor materials, but their nonlinear optical properties have been seldom touched upon. In this paper, we prepare layered CsPbBr3 nanocrystal films and characterize their physical properties. Broadband linear absorption from ~0.8 to over 2.2 μm and nonlinear optical absorption at the 1-μm wavelength region are measured. The CsPbBr3 saturable absorber (SA), manufactured by drop-casting of colloidal CsPbBr3 liquid solution on a gold mirror, shows modulation depth and saturation intensity of 13.1% and 10.7 MW/cm2, respectively. With this SA, mode-locking operation of a polarization-maintained ytterbium fiber laser produces single pulses with duration of ~216 ps, maximum average output power of 10.5 mW, and the laser spectrum is centered at ~1076 nm. This work shows that CsPbBr3 films can be efficient SA candidates for fiber lasers and also have great potential to become broadband linear and nonlinear optical materials for photonics and optoelectronics.
- Zhou, Yan,Hu, Zhiping,Li, Yue,Xu, Jianqiu,Tang, Xiaosheng,Tang, Yulong
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- Time-dependent transformation routes of perovskites CsPbBr3and CsPbCl3under high pressure
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All-inorganic halide perovskites are prospective materials for diverse applications in photovoltaic and optoelectronic devices. Their high performance is associated with good operational stability, which is the key problem of hybrid organic-inorganic perovskites. However, for these materials only fragmentary information is available on the mechanical robustness and response to external stress, fundamentally important for strain engineering in multilayers, pressure-assisted technologies, and flexible panels applications. Here we show that all-inorganic perovskites CsPbX3 (where X = Cl, Br) undergo various types of pressure-induced transformations, including reversible phase transitions, irreversible chemical reactions reducing the dimensionality of PbX6 frameworks, and amorphization. The transformation routes depend on the mode of the applied stress and are related to the kinetics of transitions to the most stable phases. The slow-kinetics transformations in a moderate pressure range of technological importance, between 0.5 and 1.5 GPa, can require days or even weeks, depending on the sample quality and external stimuli. The pressure-induced narrowing and widening of energy gaps has been explained by the mechanism combining Pb-X bond lengths and PbX6 octahedra tilts with the electronic structure of the crystals.
- Katrusiak, Andrzej,St?hl, Kenny,Szafrański, Marek
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- Centimeter-sized inorganic lead halide perovskite CsPbBr3 crystals grown by an improved solution method
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As a member of the lead-halide perovskite family, inorganic perovskite CsPbBr3 exhibits excellent optical and electrical properties with higher stability to the environment. However, former efforts to obtain large-size CsPbBr3 single crystals with satisfactory quality using low temperature solution methods reached limited results. In this work, we have studied the growth of CsPbBr3 crystals using the antisolvent vapor-assisted crystallization (AVC) method. By adjusting the mole ratio of PbBr2 and CsBr, the phase diagram of the final products is acquired. Five regions are identified, including the Cs4PbBr6 single phase region, Cs4PbBr6 and CsPbBr3 two phases region, CsPbBr3 single phase region, CsPbBr3 and PbBr2· 2[(CH3)2SO] metastable two phases region, and CsPbBr3 and PbBr2·2[(CH3)2SO] two phases region. Three methods are adopted to improve the size and crystalline quality of CsPbBr3. The growth rate is effectively tailored by diluting the antisolvent MeOH solution using DMSO to reduce the MeOH vapor pressure. Centimeter-size bright CsPbBr3 crystals have been obtained. The room temperature bandgap of CsPbBr3 is estimated at ~2.29 eV by the transmission spectra. The photoluminescence spectra show two strong emission peaks, located at 530 and 555 nm, respectively, which are related to the free and bond excitons. The resistivity is as large as 2.1 × 109 Ω· cm. Hall effect measurements demonstrate the CsPbBr3 is p-type conductivity with a hole carrier concentration of 4.55 × 107 cm-3 and the mobility of 143 cm2 V-1 s-1. The resulting Au/CsPbBr3/Au device exhibits strong photoresponse to optical light, with an on-off ratio of two orders under a light emitting diode (~1 mW/cm2) with a wavelength of 365-420 nm. Our research would shed more light on the growth and the photoresponse properties of CsPbBr3 crystals.
- Zhang, Hongjian,Liu, Xin,Dong, Jiangpeng,Yu, Hui,Zhou, Ce,Zhang, Binbin,Xu, Yadong,Jie, Wanqi
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- CsPbBr3nanowire polarized light-emitting diodes through mechanical rubbing
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Anisotropic films composed of aligned CsPbBr3nanowires (NWs) have been successfully fabricated using a mechanical rubbing method. The films with a dense and uniform morphology show polarization photoluminescence (PL) behavior. Combined with an optimal device structure, a polarized light-emitting diode (LED) with a turn-on voltage as low as 6.5 V was obtained.
- Wei, Yaping,Xu, Yinyan,Wang, Qian,Wang, Jianyue,Lu, Hongbo,Zhu, Jun
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- High-sensitivity X-ray detectors based on solution-grown caesium lead bromide single crystals
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X-ray detection is of great significance for medical diagnostics, industrial non-destructive inspection, nuclear plants and scientific research. However, high sensitivity is needed for X-ray detectors to reduce the radiation dose applied to human bodies for the applications of medical imaging and security checks. Here, we reported sensitive X-ray detectors made of solution-grown inorganic lead perovskite CsPbBr3 single crystals and the synthesis of high-quality inorganic lead perovskite CsPbBr3 single crystals using an improved low temperature solution method, which exhibited high transmittance, mobility and mobility-lifetime products. By designing the detector in an asymmetric electrode configuration, ion migration was effectively suppressed under a high voltage with a low dark current and an outstanding photoresponse. The optimized detector exhibited high sensitivity of 1256 μC Gy-1 cm-2 for 80 kVp X-ray detection under a relatively low electric field of 20 V mm-1, which was 60 times higher than that of commercially used α-Se detectors. Due to its facile synthesis, low cost, long-term stability, and high detection sensitivity, CsPbBr3 is expected to be an outstanding candidate for commercialized sensitive X-ray detectors.
- Zhang, Hongjian,Wang, Fangbao,Lu, Yufei,Sun, Qihao,Xu, Yadong,Zhang, Bin-Bin,Jie, Wanqi,Kanatzidis, Mercouri G.
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- Universal Oxide Shell Growth Enables in Situ Structural Studies of Perovskite Nanocrystals during the Anion Exchange Reaction
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The ability to tune thin oxide coatings by wetchemistry is desirable for many applications, yet it remains a key synthetic challenge. In this work, we introduce a general colloidal atomic layer deposition (c-ALD) synthesis to grow an alumina shell with tunable thickness around nanocrystalline cores of various compositions spanning from ionic semiconductors (i.e., CsPbX3, with X = Br, I, Cl) to metal oxides and metals (i.e., CeO2 and Ag). The distinctive characteristics of each core (i.e., emission, facile surface functionalization, stability) allowed us to optimize and to elucidate the chemistry of the c-ALD process. Compared to gas-phase ALD, this newly developed synthesis has the advantage of preserving the colloidal stability of the nanocrystalline core while controlling the shell thickness from 1 to 6 nm. As one example of the opportunities offered by the growth of a thin oxide shell, we study the anion exchange reaction in the CsPbX3 perovskites nanocrystals by in situ X-ray diffraction, which had been impeded so far by the instability of this class of materials and by the fast exchange kinetics.
- Loiudice, Anna,Strach, Michal,Saris, Seryio,Chernyshov, Dmitry,Buonsanti, Raffaella
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- Low defects, large area and high stability of all-inorganic lead halide perovskite CsPbBr3 thin films with micron-grains: Via heat-spraying process for self-driven photodetector
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All-inorganic lead halide perovskite CsPbBr3 has important applications in photoelectronic devices such as photodetectors, LEDs and photovoltaic devices. However, preparing high-quality CsPbBr3 thin films has proven to be challenging. In this study, we prepared all-inorganic lead halide perovskite CsPbBr3 thin films with micron-grains (MG-CsPbBr3-TF) via a heat-spraying process (HSP) using a CsPbBr3-saturated solution (CsPbBr3-SS), and the films exhibited large area, low defects and high stability. The grain size of MG-CsPbBr3-TF was about 1-5 microns. The micron-sized grains in MG-CsPbBr3-TF enabled the absorption cutoff edge to be extended from 537 to 545 nm. In addition, the presence of fewer boundaries in MG-CsPbBr3-TF reduced the defects in MG-CsPbBr3-TF (the blue shift of luminescence). The response wavelengths of a low-cost and self-driven (zero-biased) photodetector based on MG-CsPbBr3-TF were from 330 to 600 nm. CsPbBr3 thin films having a large area (10 cm × 10 cm) and micron-sized grains were also prepared by HSP and exhibited excellent stability (1944 h) in air (T = 298 K, 40% humidity). To the best of our knowledge, this is the first study of high-quality CsPbBr3 thin films prepared by HSP. The results are of great interest for both fundamental research and practical applications of CsPbBr3 in photodetectors, LEDs and photovoltaic devices.
- Zhou, Huawei,Fan, Lin,He, Guohang,Yuan, Cang,Wang, Yunying,Shi, Shaozhen,Sui, Ning,Chen, Baoli,Zhang, Yingtian,Yao, Qingxia,Zhao, Jinsheng,Zhang, Xianxi,Yin, Jie
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- Zinc ions doped cesium lead bromide perovskite nanocrystals with enhanced efficiency and stability for white light-emitting diodes
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All-inorganic cesium lead halide perovskite nanocrystals (NCs) are considered as an excellent candidate material for light-emitting devices (LED) displays because of their great photo-physical properties. However, the efficiency and stability of these materials are still unsatisfactory, which is the main disadvantage hindering the commercialization of the perovskite NCs based LED displays. On the other hand, the poisonous element lead (Pb) restricted the large-scale application of the perovskite NCs. Here we reported a hot-injection method by doping zinc ions into the CsPbBr3 NCs with enhanced photoluminescence (PL) properties and stability in ambient air. The doped NCs exhibit the highest photoluminescence quantum yield (PLQY) of 91.3% and a narrow full width at half-maximum (FWHM) of 15.5 nm. The improved the optical properties and stability of the doped NCs may result from the enhanced formation energies of perovskite lattices and the surface passivation. Finally, a white light-emitting diode (WLED) was fabricated by combining the green-emitting CsPbBr3:Zn2+ doped NCs and red-emitting K2SiF6:Mn6+ phosphors along with a blue LED chip, which exhibits a luminous efficiency of 36 lm/W, a chromaticity coordinate of (0.327, 0.336), a color temperature (CCT) of 5760 K and a wide color gamut (137% of the National Television System Committee).
- Chen, Renjie,Xu, Yan,Wang, Song,Xia, Chao,Liu, Yunpeng,Yu, Bingjie,Xuan, Tongtong,Li, Huili
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- Unveiling the Photo- and Thermal-Stability of Cesium Lead Halide Perovskite Nanocrystals
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Lead halide perovskites possess unique characteristics that are well-suited for optoelectronic and energy capture devices, however, concerns about their long-term stability remain. Limited stability is often linked to the methylammonium cation, and all-inorganic CsPbX3 (X=Cl, Br, I) perovskite nanocrystals have been reported with improved stability. In this work, the photostability and thermal stability properties of CsPbX3 (X=Cl, Br, I) nanocrystals were investigated by means of electron microscopy, X-ray diffraction, thermogravimetric analysis coupled with FTIR (TGA-FTIR), ensemble and single particle spectral characterization. CsPbBr3 was found to be stable under 1-sun illumination for 16 h in ambient conditions, although single crystal luminescence analysis after illumination using a solar simulator indicates that the luminescence states are changing over time. CsPbBr3 was also stable to heating to 250 °C. Large CsPbI3 crystals (34±5 nm) were shown to be the least stable composition under the same conditions as both XRD reflections and Raman bands diminish under irradiation; and with heating the γ (black) phase reverts to the non-luminescent δ phase. Smaller CsPbI3 nanocrystals (14±2 nm) purified by a different washing strategy exhibited improved photostability with no evidence of crystal growth but were still thermally unstable. Both CsPbCl3 and CsPbBr3 show crystal growth under irradiation or heat, likely with a preferential orientation based on XRD patterns. TGA-FTIR revealed nanocrystal mass loss was only from liberation and subsequent degradation of surface ligands. Encapsulation or other protective strategies should be employed for long-term stability of these materials under conditions of high irradiance or temperature.
- Boote, Brett W.,Andaraarachchi, Himashi P.,Rosales, Bryan A.,Blome-Fernández, Rafael,Zhu, Feng,Reichert, Malinda D.,Santra, Kalyan,Li, Jingzhe,Petrich, Jacob W.,Vela, Javier,Smith, Emily A.
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- Efficient white LEDs with bright green-emitting CsPbBr3 perovskite nanocrystal in mesoporous silica nanoparticles
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Metal-halide perovskites have been hailed as remarkable materials for photovoltaic devices and, recently, their star has also been on the rise in optoelectronics and photonics. Nevertheless, challenging issues, such as the thermal/chemical stability and high-performance devices with long-term stability, limit their practical applications. Here, we successfully prepared CsPbBr3 NCs incorporated into mesoporous silica (NCs-MS) by a simple stirred of MS with CsPbBr3 NCs blended in toluene solution. The resultant NCs-MS nanocomposite exhibit excellent optical performance and good thermal and photostability under illumination of UV light for 120 h. Additionally, NCs-MS nanocomposite is resistant to water, which are beneficial for the fabrication of white light-emitting diode (WLED) devices. Thereby a WLED was constructed by combining NCs-MS nanocomposite with Sr2Si5N8:Eu2+ red phosphor on an InGaN blue chip, achieving a highly efficient luminous efficacy of 47.6 lm/W. Moreover, the WLED also demonstrate wonderful color stability under 120 mA current. This work opens up the exciting opportunity of using all-inorganic CsPbBr3 NCs-MS nanocomposite for high performance and low-cost WLEDs applications.
- Di, Xiaoxuan,Shen, Ludi,Jiang, Jutao,He, Meiling,Cheng, Yinzi,Zhou, Lei,Liang, Xiaojuan,Xiang, Weidong
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- An Inverse Opal Structured Halide Perovskite Photocatalyst
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We employ a colloidal crystal templating approach to fabricate ordered macro-mesoporous CsPbBr3 and demonstrate its superior photocatalytic activity compared to its non-templated counterpart in the degradation of an organic pollutant. The prese
- Schünemann, Stefan,Tüysüz, Harun
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- Metal Halide Perovskite Supercrystals: Gold-Bromide Complex Triggered Assembly of CsPbBr3 Nanocubes
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Using nanocrystals as "artificial atoms" to construct supercrystals is an interesting process to explore the stacking style of nanoscale building blocks and corresponding collective properties. Various types of semiconducting supercrystals have been constructed via the assembly of nanocrystals driven by the entropic, electrostatic, or van der Waals interactions. We report a new type of metal halide perovskite supercrystals via the gold-bromide complex triggered assembly of newly emerged attractive CsPbBr3 nanocubes. Through introducing gold-bromide (Au-Br) complexes into CsPbBr3 nanocubes suspension, the self-assembly process of CsPbBr3 nanocubes to form supercrystals was investigated with the different amount of Au-Br complexes added to the suspensions, which indicates that the driven force of the formation of CsPbBr3 supercrystals included the van der Waals interactions among carbon chains and electrostatic interactions between Au-Br complexes and surfactants. Accordingly, the optical properties change with the assembly of CsPbBr3 nanocubes and the variation of mesoscale structures of supercrystals with heating treatment was revealed as well, demonstrating the ionic characteristics of CsPbBr3 nanocrystals. The fabricated CsPbBr3 supercrystal presents a novel type of semiconducting supercrystals that will open an avenue for the assembly of ionic nanocrystals.
- Wang, Kun-Hua,Yang, Jun-Nan,Ni, Qian-Kun,Yao, Hong-Bin,Yu, Shu-Hong
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- Synthesis of all-inorganic CsPb2Br5 perovskite and determination of its luminescence mechanism
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All-inorganic cesium lead halide perovskite materials, such as CsPbBr3 and CsPb2Br5, have drawn immense attention recently due to their potential applications in optoelectronics. However, unlike the extensively-studied CsPbBr3, many of the fundamental properties of CsPb2Br5 remain unclear, such as its electronic structure and photoluminescence (PL) mechanism. In this work, we developed a novel environmentally friendly chemical method to synthesize CsPb2Br5, where only water and ethanol were used as solvents. The optical property and electronic structure of CsPb2Br5 were then examined both experimentally and theoretically. For the first time we found that the band-edge emission of CsPb2Br5 was not in the visible range as reported in the literature but rather located in the ultraviolet range. By monitoring the PL property during phase conversion between CsPb2Br5 and CsPbBr3, we propose that previously-reported visible emission might be due to the involvement of CsPbBr3 during sample preparation. Overall, this study presents a novel green method for the preparation of CsPb2Br5 and clarifies the optical properties and electronic structure of CsPb2Br5.
- Li, Jing,Zhang, Huijie,Wang, Song,Long, Debing,Li, Mingkai,Guo, Yizhong,Zhong, Zhicheng,Wu, Kaifeng,Wang, Duofa,Zhang, Tianjin
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- Mechanochemical synthesis of a processable halide perovskite quantum dot-MOF composite by post-synthetic metalation
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Perovskite quantum dots (PQDs) are some of the most sought after materials for optoelectronic and photovoltaic applications. We report the mechanochemical, solvent-free synthesis of a PQD?MOF composite using a post-synthetically PbII metalated
- Bhattacharyya, Sohini,Rambabu, Darsi,Maji, Tapas Kumar
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- Photoluminescence Quenching in Self-Assembled CsPbBr3 Quantum Dots on Few-Layer Black Phosphorus Sheets
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An ordered self-assembly of CsPbBr3 quantum dots (QDs) was generated on the surface of few-layer black phosphorus (FLBP). Strong quenching of the QD fluorescence was observed, and analyzed by time-resolved photoluminescence (TR-PL) studies, DFT
- Muduli, Subas,Pandey, Padmini,Devatha, Gayathri,Babar, Rohit,Thripuranthaka,Kothari, Dushyant C.,Kabir, Mukul,Pillai, Pramod P.,Ogale, Satishchandra
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- Engineering Sensitized Photon Upconversion Efficiency via Nanocrystal Wavefunction and Molecular Geometry
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Triplet energy transfer from inorganic nanocrystals to molecular acceptors has attracted strong attention for high-efficiency photon upconversion. Here we study this problem using CsPbBr3 and CdSe nanocrystals as triplet donors and carboxylated anthracene isomers as acceptors. We find that the position of the carboxyl anchoring group on the molecule dictates the donor-acceptor coupling to be either through-bond or through-space, while the relative strength of the two coupling pathways is controlled by the wavefunction leakage of nanocrystals that can be quantitatively tuned by nanocrystal sizes or shell thicknesses. By simultaneously engineering molecular geometry and nanocrystal wavefunction, energy transfer and photon upconversion efficiencies of a nanocrystal/molecule system can be improved by orders of magnitude.
- Han, Yaoyao,He, Shan,Jiang, Qike,Lai, Runchen,Liu, Xue,Luo, Xiao,Tian, Yuyang,Wu, Kaifeng
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- Reversible transformation between CsPbBr3 nanowires and nanoparticles
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We show that CsPbBr3 nanowires (NWs) are formed by the hierarchical arrangement of individual nanoparticles (NPs), and reversible transformation from NWs to NPs is also achieved by anion exchange.
- Ji, Yongqiang,Wang, Minqiang,Yang, Zhi,Ji, Shangdong,Qiu, Hengwei,Dou, Jinjuan,Gaponenko, Nikolai V.
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- Highly Luminescent Copper Iodide Cluster Based Inks with Photoluminescence Quantum Efficiency Exceeding 98%
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Highly luminescent inks are desirable for various applications such as decorative coating, art painting, and anticounterfeiting, to name a few. However, present inks display low photoluminescent efficiency requiring a strong excitation light to make them glow. Here, we report a highly luminescent ink based on the copper-iodide/1-Propyl-1,4-diazabicyclo[2.2.2]octan-1-ium (Cu4I6(pr-ted)2) hybrid cluster with a quantum efficiency exceeding 98%. Under the interaction between the Cu4I6(pr-ted)2 hybrid cluster and polyvinylpyrrolidone (PVP), the highly luminescent Cu4I6(pr-ted)2/PVP ink can be facilely prepared via the one-pot solution synthesis. The obtained ink exhibits strong green light emission that originates from the efficient phosphorescence of Cu4I6(pr-ted)2 nanocrystals. Attractively, the ink displays high conversion efficiency for the ultraviolet light to bright green light emission due to its wide Stokes shift, implying great potential for anticounterfeiting and luminescent solar concentrator coating.
- Chen, Chen,Chen, Wei-Guo,Fan, Feng-Jia,Feng, Li-Zhe,Ma, Cheng,Wang, Jing-Jing,Wang, Kun-Hua,Yang, Jun-Nan,Yao, Hong-Bin,Yao, Ji-Song,Yao, Ming-Ming,Yin, Yi-Chen
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- An All-Inorganic Perovskite-Phase Rubidium Lead Bromide Nanolaser
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Rubidium lead halides (RbPbX3), an important class of all-inorganic metal halide perovskites, are attracting increasing attention for photovoltaic applications. However, limited by its lower Goldschmidt tolerance factor t≈0.78, all-inorganic RbPbBr3 has not been reported. Now, the crystal structure, X-ray diffraction (XRD) pattern, and band structure of perovskite-phase RbPbBr3 has now been investigated. Perovskite-phase RbPbBr3 is unstable at room temperature and transforms to photoluminescence (PL)-inactive non-perovskite. The structural evolution and mechanism of the perovskite–non-perovskite phase transition were clarified in RbPbBr3. Experimentally, perovskite-phase RbPbBr3 was realized through a dual-source chemical vapor deposition and annealing process. These perovskite-phase microspheres showed strong PL emission at about 464 nm. This new perovskite can serve as a gain medium and microcavity to achieve broadband (475–540 nm) single-mode lasing with a high Q of about 2100.
- Tang, Bing,Hu, Yingjie,Dong, Hongxing,Sun, Liaoxin,Zhao, Binbin,Jiang, Xiongwei,Zhang, Long
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- High-quality CsPbBr3 perovskite nanocrystals for quantum dot light-emitting diodes
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Metal halide perovskites, such as CsPbX3 (X = Cl, Br, and I), have gained extensive attention due to their increasing demand in optoelectronic applications such as solar cells and lighting-emitting devices. Herein, we report a versatile approach to synthesize high-quality CsPbBr3 perovskite nanocrystals (sized 5-15 nm) by ligand-assisted reprecipitation at room temperature. The monodispersed CsPbBr3 nanocube perovskites displayed relatively high photoluminescence quantum yields of 50-80%. By virtue of the quantum size effects, the bandgap energies were manipulated from blue to green spectral regions (410-530 nm). In addition, through compositional modulations of the anion exchange technique, the bright photoluminescence could be almost tuned over the entire visible spectral region (450-650 nm). Furthermore, the photoluminescence of the CsPbBr3 nanocrystals was characterized by narrow emission line widths of 15-50 nm and radiative lifetimes of 5-15 ns. Finally, by taking advantage of these outstanding merits, the CsPbBr3 perovskites were successfully utilized in the application of highly fluorescent patterning and color-purity light-emitting diodes.
- Du, Xiafang,Wu, Guan,Cheng, Jian,Dang, Hui,Ma, Kangzhe,Zhang, Ya-Wen,Tan, Peng-Feng,Chen, Su
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- Large-Scale Synthesis of Highly Luminescent Perovskite-Related CsPb2Br5Nanoplatelets and Their Fast Anion Exchange
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All-inorganic cesium lead-halide perovskite nanocrystals have emerged as attractive optoelectronic nanomaterials owing to their stabilities and highly efficient photoluminescence. Herein we report a new type of highly luminescent perovskite-related CsPb2Br5nanoplatelets synthesized by a facile precipitation reaction. The layered crystal structure of CsPb2Br5promoted an anisotropic two-dimensional (2D) crystal growth during the precipitation process, thus enabling the large-scale synthesis of CsPb2Br5nanoplatelets. Fast anion exchange has also been demonstrated in as-synthesized CsPb2Br5nanoplatelets to extend their photoluminescence spectra to the entire visible spectral region. The large-scale synthesis and optical tunability of CsPb2Br5nanoplatelets will be advantageous in future applications of optoelectronic devices.
- Wang, Kun-Hua,Wu, Liang,Li, Lei,Yao, Hong-Bin,Qian, Hai-Sheng,Yu, Shu-Hong
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- Stable and Efficient Blue-Emitting CsPbBr3 Nanoplatelets with Potassium Bromide Surface Passivation
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Colloidal all-inorganic perovskites nanocrystals (NCs) have emerged as a promising material for display and lighting due to their excellent optical properties. However, blue emissive NCs usually suffer from low photoluminescence quantum yields (PLQYs) and poor stability, rendering them the bottleneck for full-color all-perovskite optoelectronic applications. Herein, a facile approach is reported to enhance the emission efficiency and stability of blue emissive perovskite nano-structures via surface passivation with potassium bromide. By adding potassium oleate and excess PbBr2 to the perovskite precursor solutions, potassium bromide-passivated (KBr-passivated) blue-emitting (≈450 nm) CsPbBr3 nanoplatelets (NPLs) is successfully synthesized with a respectably high PLQY of 87%. In sharp contrast to most reported perovskite NPLs, no shifting in emission wavelength is observed in these passivated NPLs even after prolonged exposures to intense irradiations and elevated temperature, clearly revealing their excellent photo- and thermal-stabilities. The enhancements are attributed to the formation of K-Br bonding on the surface which suppresses ion migration and formation of Br-vacancies, thus improving both the PL emission and stability of CsPbBr3 NPLs. Furthermore, all-perovskite white light-emitting diodes (WLEDs) are successfully constructed, suggesting that the proposed KBr-passivated strategy can promote the development of the perovskite family for a wider range of optoelectronic applications.
- Lin, Hao,Wei, Qi,Ng, Kar Wei,Dong, Jia-Yi,Li, Jie-Lei,Liu, Wei-Wei,Yan, Shan-Shan,Chen, Shi,Xing, Gui-Chuan,Tang, Xiao-Sheng,Tang, Zi-Kang,Wang, Shuang-Peng
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- Low-Temperature Solution Growth and Characterization of Halogen (Cl, I)-Doped CsPbBr3 Crystals
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The all-inorganic halide perovskite CsPbBr3 exhibited extraordinary photoelectric properties as well as great potential for various optic-electronic devices. The introduction of a Cl/I dopant is an effective method to optimize their properties. However, it is still a challenge to grow doped CsPbBr3 single crystals from solution. In this work, we report on the crystal growth of Cl/I-doped CsPbBr3 crystals using the modified inverse temperature crystallization (ITC) method. The components of raw materials and solvent in precursors were precisely tailored. The resulting doping ratio between the actual content and the nominal content are 0.99 and 0.046 for Cl and I, respectively. It indicates that I ion doped crystals exhibit more severe stoichiometric deviation due to the lower decomposition energy. The crystal structure, morphology, and optical properties of doped crystals were also investigated systematically. The {101} and {010} facets of as-grown crystals were influenced by the doping process. PL and UV transmittance spectra exhibited changes in the band gap in Cl/I-doped crystals. Finally, the phase diagram of basic photoelectric properties was determined for CsPb(Br1-nCln)3 crystals and it reveals conductive type changes from the P type to N type with an increase in the doping content of the Cl element. The optimum component of CsPb(Br0.93Cl0.07)3 demonstrates the highest resistivity of 4.3 × 109 ω cm, an on/off ratio of ~40, and a mobility of 414 cm2 V-1 s-1 as well as the lowest carrier concentration of 3.57 × 107 cm-3. Our work provides a strategy to grow doped halide perovskite crystals and tailor their optical and electrical properties.
- Wang, Fangbao,Zhang, Hongjian,Sun, Qihao,Hafsia, Ahmed Ben,Chen, Zhangxuan,Zhang, Binbin,Xu, Yadong,Jie, Wanqi
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- Stable Blue Luminescent CsPbBr3 Perovskite Nanocrystals Confined in Mesoporous Thin Films
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Creating CsPbBr3 perovskite nanocrystals with bright blue emission is challenging because their optical properties depend sensitively on structure. Growing perovskites in mesoporous templates bypasses some of these purification issues because the size of the nanocrystal is governed by the dimensions of the pores. Mesoporous silica consisting of aligned channels with tunable diameter can be easily synthesized and used as a template. When the perovskite solution evaporates and retreats, some of the liquid remains trapped in the interconnecting pores by discontinuous dewetting. The precursor crystallizes, generating stable ca. 3.1 nm blue-emitting perovskite nanocrystals. The mesoporous template also serves as a protective barrier to preserve the optical properties of the CsPbBr3 from atmospheric conditions. Compared to the bulk crystals and the powder composite, the strong blue-shift of the emission peak in the film is accompanied by a decrease in the longer lifetime component and an 8-fold increase in the external quantum efficiency.
- Malgras, Victor,Henzie, Joel,Takei, Toshiaki,Yamauchi, Yusuke
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- Phase transitions, screening and dielectric response of CsPbBr3
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Cesium-lead-bromide (CsPbBr3) is the simplest all inorganic halide perovskite. It serves as a reference material for understanding the exceptional solar cell properties of the organic-inorganic hybrid halide perovskites and is itself discussed as an alternative absorber material. Broadband dielectric spectroscopy has proven to yield an in depth understanding of charge screening mechanisms in the halide solar cell absorbers based on methylammonium and modifications hereof. For a deeper understanding of charge carrier screening, we have investigated CsPbBr3 across wide temperature (120 K-450 K) and frequency ranges. Besides the two known phase transitions at 403 K and 361 K, the dielectric data show another anomaly around 220 K, which can be interpreted as another phase transition. XRD and EPR studies confirm the presence of this anomaly, but Raman scattering spectra do not show any lattice anomalies in the vicinity of 220 K. This additional anomaly is of first order character (different transition temperatures upon cooling and heating) but hardly influences the lattice dynamics. Our broadband dielectric investigations of CsPbBr3 display the same microwave limit permittivity as for MAPbX3 (?r ≈ 30, X = Cl, Br, I, MA = CH3NH3+) but do not afford a second permittivity relaxation up to this frequency. Our prior assignment of the second contribution in the methylammonium compounds being due to the relaxation dynamics of the methylammonium ion as a dipole is herewith proven. Nevertheless, CsPbBr3 shows large charge carrier screening up to very high frequencies which can still play a vital role in charge carrier dynamics and exciton behaviour in this material as well.
- ?ablinskas, Valdas,?im?nas, Mantas,Bal?iūnas, Sergejus,Banys, Jūras,Castillo, Marianela Escobar,De Rosário Soares, Maria,Karabanov, Andrei,Kinka, Martynas,Kubicki, Dominik,Lupascu, Doru C.,Salak, Andrei N.,Shvartsman, Vladimir V.,Svirskas, ?arūnas,Usevi?ius, Gediminas,Veli?ka, Martynas
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- Microwave-Enhanced Chemistry at Solid-Liquid Interfaces: Synthesis of All-Inorganic CsPbX3 Nanocrystals and Unveiling the Anion-Induced Evolution of Structural and Optical Properties
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We demonstrate how microwaves could enhance the chemistry at interfaces of heterogeneous reactions involved in the microwave-solvothermal (MW-ST) synthesis of all-inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (PNCs) within 6 min, unlike a conventional hot-injection method that requires 3 h. The enhanced MW-ST reaction rate was quantitatively analyzed by the Eyring equation, and it has been observed that the decreased activation free energy (ΔG?) and increased activation entropy (ΔS?) are caused by changes in the relative energies of reactants at their solid-liquid interfaces, leading to the formation of hot spots , where microwave energy absorption is at its maximum. This rapid and homogeneous microwave heating could facilitate the self-assembly of uniformly distributed CsPbX3 nanocubes with precise control over the stoichiometric ratio, as confirmed by high-resolution transmission electron microscopy and energy-dispersive X-ray analyses. X-ray diffraction and Raman results indicate that lattice contraction and expansion in CsPbBr3-yXy have occurred because of an increase in the metal-halide bond length upon moving down the groups Cl → Br → I, as further ascertained by the Rietveld refinement studies. These anion-induced structural variations accordingly affected the electronic properties of MW-ST-synthesized CsPbX3 PNCs, which is apparent from the shifts in their conduction-band (CB) and valence-band (VB) positions. Consequently, the optical properties were also altered, resulting in a color-tuned emission from blue to red, with excellent photoluminescence quantum yields (up to 92%) and narrow emission line widths, as is evident from UV-vis and photoluminescence spectroscopy. The MW-ST-synthesized CsPbX3 PNCs were used as color-conversion layers for the fabrication of light-emitting diodes (LEDs) with commercial 456 nm UV-LED chips.
- Thesika, Kabalaraj,Vadivel Murugan, Arumugam
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- Ultrathin, Core–Shell Structured SiO2 Coated Mn2+-Doped Perovskite Quantum Dots for Bright White Light-Emitting Diodes
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All-inorganic semiconductor perovskite quantum dots (QDs) with outstanding optoelectronic properties have already been extensively investigated and implemented in various applications. However, great challenges exist for the fabrication of nanodevices including toxicity, fast anion-exchange reactions, and unsatisfactory stability. Here, the ultrathin, core–shell structured SiO2 coated Mn2+ doped CsPbX3 (X = Br, Cl) QDs are prepared via one facile reverse microemulsion method at room temperature. By incorporation of a multibranched capping ligand of trioctylphosphine oxide, it is found that the breakage of the CsPbMnX3 core QDs contributed from the hydrolysis of silane could be effectively blocked. The thickness of silica shell can be well-controlled within 2 nm, which gives the CsPbMnX3@SiO2 QDs a high quantum yield of 50.5% and improves thermostability and water resistance. Moreover, the mixture of CsPbBr3 QDs with green emission and CsPbMnX3@SiO2 QDs with yellow emission presents no ion exchange effect and provides white light emission. As a result, a white light-emitting diode (LED) is successfully prepared by the combination of a blue on-chip LED device and the above perovskite mixture. The as-prepared white LED displays a high luminous efficiency of 68.4 lm W?1 and a high color-rendering index of Ra = 91, demonstrating their broad future applications in solid-state lighting fields.
- Tang, Xiaosheng,Chen, Weiwei,Liu, Zhengzheng,Du, Juan,Yao, Zhiqiang,Huang, Yi,Chen, Cheng,Yang, Zhaoqi,Shi, Tongchao,Hu, Wei,Zang, Zhigang,Chen, Yu,Leng, Yuxin
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- Triplet Energy Transfer from Perovskite Nanocrystals Mediated by Electron Transfer
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Triplet energy transfer from colloidal nanocrystals is a novel approach to sensitizing molecular triplets that are important for many applications. Recent studies suggest that this triplet transfer can be mediated by a hole transfer process when it is energetically allowed. In contrast, electron-transfer-mediated triplet transfer has not been observed yet, which is likely due to hole-trapping in typical II-VI group nanocrystals inhibiting the hole transfer step following initial electron transfer and hence disrupting a complete triplet exciton transfer. Here we report electron-transfer-mediated triplet energy transfer from CsPbCl3 and CsPbBr3 perovskite nanocrystals to surface-anchored rhodamine molecules. The mechanism was unambiguously established by ultrafast spectroscopy; control experiments using CdS nanocrystals also confirmed the role of hole-trapping in inhibiting this mechanism. The sensitized rhodamine triplets engaged in a variety of applications such as photon upconversion and singlet oxygen generation. Compared to conventional one-step triplet transfer, the electron-transfer-mediated mechanism is less demanding in terms of interfacial electronic coupling and hence is more generally implementable. Overall, this study not only establishes a complete framework of triplet energy transfer across nanocrystal/molecule interfaces but also greatly expands the scope of molecular triplet sensitization using nanocrystals.
- Luo, Xiao,Liang, Guijie,Han, Yaoyao,Li, Yulu,Ding, Tao,He, Shan,Liu, Xue,Wu, Kaifeng
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- Triplet Energy Transfer from CsPbBr3 Nanocrystals Enabled by Quantum Confinement
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The spectral properties of lead halide perovskite nanocrystals (NCs) can be engineered by tuning either their sizes via the quantum confinement effect or their compositions using anion and/or cation exchange. To date, the latter is more frequently adopted, primarily because of the ease of ion exchange for lead halide perovskites, making the quantum confinement effect seemingly redundant for perovskite NCs. Here we report that quantum confinement is required for triplet energy transfer (TET) from perovskite NCs to polycyclic aromatic hydrocarbons (PAHs). Static and transient spectroscopy measurements on CsPbBr3 NC-pyrene hybrids showed that efficient TET occurred only for small-sized, quantum-confined CsPbBr3 NCs. The influences of the size-dependent driving force and spectral overlap on the TET rate were found to be negligible. Instead, the TET rate scaled linearly with carrier probability density at the NC surface, consistent with a Dexter-type TET mechanism requiring wave function exchange between the NC donors and pyrene acceptors. Efficient TET funnels the excitation energy generated in strongly light-absorbing perovskite NCs into long-lived triplets in PAHs, which may find broad applications such as photon upconversion and photoredox catalysis.
- Luo, Xiao,Lai, Runchen,Li, Yulu,Han, Yaoyao,Liang, Guijie,Liu, Xue,Ding, Tao,Wang, Junhui,Wu, Kaifeng
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- Depressed Phase Transitions and Thermally Persistent Local Distortions in CsPbBr3 Quantum Dots
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The optoelectronic properties of CsPbX3 quantum dots (where X = Cl, Br, or I) are influenced by both their local and average structures. Variable-temperature synchrotron X-ray diffraction measurements of CsPbBr3 quantum dots show tha
- Cottingham, Patrick,Brutchey, Richard L.
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- Revealing the Formation Mechanism of CsPbBr3 Perovskite Nanocrystals Produced via a Slowed-Down Microwave-Assisted Synthesis
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We developed a microwave-assisted slowed-down synthesis of CsPbBr3 perovskite nanocrystals, which retards the reaction and allows us to gather useful insights into the formation mechanism of these nanoparticles, by examining the intermediate stages of their growth. The trends in the decay of the emission intensity of CsPbBr3 nanocrystals under light exposure are well correlated with their stability against decomposition in TEM under electron beam. The results show the change of the crystal structure of CsPbBr3 nanocrystals from a deficient and easier to be destroyed lattice to a well crystallized one. Conversely the shift in the ease of degradation sheds light on the formation mechanism, indicating first the formation of a bromoplumbate ionic scaffold, with Cs-ion infilling lagging a little behind. Increasing the cation to halide ratio towards the stoichiometric level may account for the improved radiative recombination rates observed in the longer reaction time materials.
- Li, Yanxiu,Huang, He,Xiong, Yuan,Kershaw, Stephen V.,Rogach, Andrey L.
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- Room-temperature and gram-scale synthesis of CsPbX3 (X = Cl, Br, I) perovskite nanocrystals with 50-85% photoluminescence quantum yields
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All inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (PNCs) with 50-85% photoluminescence quantum yields and tunable emission in the range of 440-682 nm have been successfully synthesized at room temperature in open air. This facile strategy enables us to prepare gram-scale CsPbBr3 NCs with a PLQY approaching 80%.
- Wei, Song,Yang, Yanchun,Kang, Xiaojiao,Wang, Lan,Huang, Lijian,Pan, Daocheng
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- Continuous Synthesis of Highly Stable Cs4PbBr6 Perovskite Microcrystals by a Microfluidic System and Their Application in White-Light-Emitting Diodes
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In this paper, we report a simple, rapid, and stable method for the continuous synthesis of highly stable Cs4PbBr6 perovskite microcrystals (MCs) using a microfluidic system. To demonstrate the potential application of Cs4PbBr6 MCs, the sample was fabricated with K2SiF6:Mn4+ phosphor onto InGaN blue chips as white-light-emitting diodes (LEDs). Our white-LED device achieved a high National Television Standards Committee value of 119% for backlight display, which indicated that the Cs4PbBr6 MC is a promising material for future applications.
- Bao, Zhen,Wang, Hung-Chia,Jiang, Zhen-Feng,Chung, Ren-Jei,Liu, Ru-Shi
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- Growth and characterization of all-inorganic lead halide perovskite semiconductor CsPbBr3 single crystals
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As a typical representative of all-inorganic lead halide perovskites, cesium lead bromide (CsPbBr3) has attracted significant attention in the context of photovoltaics and other optoelectronic applications in recent years. In this paper, CsPbBr3 single crystal growth was conducted by a creative electronic dynamic gradient (EDG) method. The crystal structure was systematically investigated using scientific instruments and equipment. X-ray diffraction techniques, including X-ray diffraction (XRD), temperature-dependent X-ray powder diffraction and the X-ray rocking curve, were used to identify the phase and to investigate phase transition rules. Electron diffraction techniques, including high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and electron backscatter diffraction (EBSD), were used to investigate the crystal micro-structure. The final results indicated that the grown CsPbBr3 crystal was a perfect single crystal preferentially orienting in the (110) direction and met the basic demand of its applications.
- Zhang, Mingzhi,Zheng, Zhiping,Fu, Qiuyun,Chen, Zheng,He, Jianle,Zhang, Sen,Yan, Liang,Hu, Yunxiang,Luo, Wei
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- All-Solid-State Mechanochemical Synthesis and Post-Synthetic Transformation of Inorganic Perovskite-type Halides
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All-inorganic and hybrid perovskite type halides are generally synthesized by solution-based methods, with the help of long chain organic capping ligands, complex organometallic precursors, and high boiling organic solvents. Herein, a room temperature, solvent-free, general, and scalable all-solid-state mechanochemical synthesis is demonstrated for different inorganic perovskite type halides, with versatile structural connectivity in three (3D), two (2D), and zero (0D) dimensions. 3D CsPbBr3, 2D CsPb2Br5, 0D Cs4PbBr6, 3D CsPbCl3, 2D CsPb2Cl5, 0D Cs4PbCl6, 3D CsPbI3, and 3D RbPbI3 have all been synthesized by this method. The all-solid-state synthesis is materialized through an inorganic retrosynthetic approach, which directs the decision on the solid-state precursors (e.g., CsX and PbX2 (X=Cl/Br/I) with desired stoichiometric ratios. Moreover, post-synthetic structural transformations from 3D to 2D and 0D perovskite halides were performed by the same mechanochemical synthetic approach at room temperature.
- Pal, Provas,Saha, Sujoy,Banik, Ananya,Sarkar, Arka,Biswas, Kanishka
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- From Precursor Powders to CsPbX3 Perovskite Nanowires: One-Pot Synthesis, Growth Mechanism, and Oriented Self-Assembly
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The colloidal synthesis and assembly of semiconductor nanowires continues to attract a great deal of interest. Herein, we describe the single-step ligand-mediated synthesis of single-crystalline CsPbBr3 perovskite nanowires (NWs) directly from the precursor powders. Studies of the reaction process and the morphological evolution revealed that the initially formed CsPbBr3 nanocubes are transformed into NWs through an oriented-attachment mechanism. The optical properties of the NWs can be tuned across the entire visible range by varying the halide (Cl, Br, and I) composition through subsequent halide ion exchange. Single-particle studies showed that these NWs exhibit strongly polarized emission with a polarization anisotropy of 0.36. More importantly, the NWs can self-assemble in a quasi-oriented fashion at an air/liquid interface. This process should also be easily applicable to perovskite nanocrystals of different morphologies for their integration into nanoscale optoelectronic devices.
- Tong, Yu,Bohn, Bernhard J.,Bladt, Eva,Wang, Kun,Müller-Buschbaum, Peter,Bals, Sara,Urban, Alexander S.,Polavarapu, Lakshminarayana,Feldmann, Jochen
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- Tunable electrochemiluminescence properties of CsPbBr3 perovskite nanocrystals using mixed-monovalent cations
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Herein, we demonstrate a simple approach for tuning the elecrochemiluminescence (ECL) properties of CsPbBr3 perovskite nanocrystals (NCs) by using mixed-monovalent cations. By replacing some of the Cs+ with Rb+, a series of RbxCs1-xPbBr3 NCs were obtained. They exhibit a narrow ECL emission peak with a full width at half-maximum of about 26-34 nm. After continuously injecting holes to produce different charged state radicals, an annihilation ECL was observed, implying that the as-prepared RbxCs1-xPbBr3 NCs are in an electron-rich state. In the presence of 2-dibutyaminoethanol as a co-reactant, strong anodic ECL of RbxCs1-xPbBr3 NCs was obtained. From CsPbBr3 NCs to RbPbBr3 NCs, the ECL peak potential position moved from 1.25 V to 1.80 V with the ECL spectrum peak shifting from 512 to 468 nm, respectively, indicating the tunable ECL properties. The Rb0.2Cs0.8PbBr3 NCs have a higher ECL intensity than the CsPbBr3 NCs.
- Zhang, Bin,Chen, Lu,Kang, Qi,Li, Zhe,Shen, Dazhong,Zou, Guizheng
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- Mesoporous Silica Particles Integrated with All-Inorganic CsPbBr3Perovskite Quantum-Dot Nanocomposites (MP-PQDs) with High Stability and Wide Color Gamut Used for Backlight Display
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All-inorganic CsPbX3(X=I, Br, Cl) perovskite quantum dots (PQDs) have been investigated because of their optical properties, such as tunable wavelength, narrow band, and high quantum efficiency. These features have been used in light emitting diode (LED) devices. LED on-chip fabrication uses mixed green and red quantum dots with silicone gel. However, the ion-exchange effect widens the narrow emission spectrum. Quantum dots cannot be mixed because of anion exchange. We address this issue with a mesoporous PQD nanocomposite that can prevent ion exchange and increase stability. We mixed green quantum-dot-containing mesoporous silica nanocomposites with red PQDs, which can prevent the anion-exchange effect and increase thermal and photo stability. We applied the new PQD-based LEDs for backlight displays. We also used PQDs in an on-chip LED device. Our white LED device for backlight display passed through a color filter with an NTSC value of 113 % and Rec. 2020 of 85 %.
- Wang, Hung-Chia,Lin, Shin-Ying,Tang, An-Cih,Singh, Bheeshma Pratap,Tong, Hung-Chun,Chen, Ching-Yi,Lee, Yu-Chun,Tsai, Tzong-Liang,Liu, Ru-Shi
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- Solution-Processed MAPbBr3 and CsPbBr3 Single-Crystal Detectors with Improved X-Ray Sensitivity via Interfacial Engineering
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Organic–inorganic hybrid perovskites have been recognized as prospective materials for use in radiation detection application due to their high atomic number, ease of crystal processing, and excellent electronic properties. Herein, solution-synthesized MAPbBr3 and CsPbBr3 detectors with different structures are constructed. Charge diffusion length and trap density analysis reveal that CsPbBr3 possesses better thermal stability but worse charge-transport properties than MAPbBr3. To improve the signal current under X-ray radiation, MoO3 is applied as a hole-extraction layer to increase hole-carrier collection. The sensitivity of X-ray detectors with MoO3 layer can reach up to 2552 μC Gyair ?1 cm?2 at an electric field of 45 V cm?1, which is higher than that without the MoO3 layer. It is shown that charge-transport capability significantly affects the response of the signal current to X-ray radiation; it also reveals the importance of interface engineering as a means to realize high-sensitivity X-ray detectors.
- Fan, Zhengfang,Liu, Jiang,Zuo, Wentao,Liu, Guoqiang,He, Xulin,Luo, Kun,Ye, Qinyan,Liao, Cheng
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- Environmentally-friendly synthesis of highly luminescent cesium lead halide perovskite nanocrystals using Sn-based halide precursors
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In the last several years, cesium lead halide perovskite (CsPbX3, X = Cl, Br, I) nanocrystals (NCs) have attracted much attention as promising kinds of optoelectronic and photonic materials. Via anion exchange reactions, the photoluminescence spectra of the CsPbX3 NCs can be tuned over nearly the entire visible spectral region. However, the preparation of the anion-exchange sources, mainly Pb-based halide precursors or oleylammonium halide precursors, would use large amounts of PbX2 (X = Cl, Br, I), trioetylphosphine (TOP) and HX (X = Cl, Br, I). These chemicals are toxic and environmentally-hazardous. To solve this problem, we report the synthesis of CsPbX3 (X = Cl, Br, I or mixed halides) NCs through modified anion exchange reactions. Using two kinds of Sn-based halide precursors as the anion-exchange sources, we can finely tune the chemical compositions and optical properties of pre-synthesized CsPbX3 NCs. Considering no PbX2, TOP and HX have been used in the preparation of the Sn-based halide precursors, we can determine this two-pot synthetic scheme as a step toward a green-chemistry approach for synthesizing high quality CsPbX3 NCs.
- Wang, Pengchao,Dong, Bohua,Cui, Zhenjie,Gao, Rongjie,Su, Ge,Wang, Wei,Cao, Lixin
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- Highly Luminescent Cesium Lead Halide Perovskite Nanocrystals with Tunable Composition and Thickness by Ultrasonication
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We describe the simple, scalable, single-step, and polar-solvent-free synthesis of high-quality colloidal CsPbX3(X=Cl, Br, and I) perovskite nanocrystals (NCs) with tunable halide ion composition and thickness by direct ultrasonication of the c
- Tong, Yu,Bladt, Eva,Aygüler, Meltem F.,Manzi, Aurora,Milowska, Karolina Z.,Hintermayr, Verena A.,Docampo, Pablo,Bals, Sara,Urban, Alexander S.,Polavarapu, Lakshminarayana,Feldmann, Jochen
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- Solution-Phase Synthesis of Cesium Lead Halide Perovskite Nanowires
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Halide perovskites have attracted much attention over the past 5 years as a promising class of materials for optoelectronic applications. However, compared to hybrid organic-inorganic perovskites, the study of their pure inorganic counterparts, like cesium lead halides (CsPbX3), lags far behind. Here, a catalyst-free, solution-phase synthesis of CsPbX3 nanowires (NWs) is reported. These NWs are single-crystalline, with uniform growth direction, and crystallize in the orthorhombic phase. Both CsPbBr3 and CsPbI3 are photoluminescence active, with composition-dependent temperature and self-trapping behavior. These NWs with a well-defined morphology could serve as an ideal platform for the investigation of fundamental properties and the development of future applications in nanoscale optoelectronic devices based on all-inorganic perovskites.
- Zhang, Dandan,Eaton, Samuel W.,Yu, Yi,Dou, Letian,Yang, Peidong
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- Highly Emissive Divalent-Ion-Doped Colloidal CsPb1-xMxBr3 Perovskite Nanocrystals through Cation Exchange
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Colloidal CsPbX3 (X = Br, Cl, and I) perovskite nanocrystals (NCs) have emerged as promising phosphors and solar cell materials due to their remarkable optoelectronic properties. These properties can be tailored by not only controlling the size
- Van der Stam, Ward,Geuchies, Jaco J.,Altantzis, Thomas,Van Den Bos, Karel H. W.,Meeldijk, Johannes D.,Van Aert, Sandra,Bals, Sara,Vanmaekelbergh, Daniel,De Mello Donega, Celso
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- Amorphization-induced strong localization of electronic states in CsPbBr3 and CsPbCl3 studied by optical absorption measurements
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Optical absorption spectra of amorphous CsPbX3 films (X=Br,Cl) are characterized by two Gaussian bands near the fundamental edge, with the optical energy gap largely blueshifted and the absorption intensity strongly reduced as compared with the crystalline films. The peak energies of the bands are close to those of the A and C bands of Pb-doped alkali halides. The spectral features are discussed in terms of a molecular orbital theory based on a quasicomplex Pb2+(X-)6 model similar to the complex model for the doped alkali halides. It is shown that not only Pb2+ 6s and 6p extended states near the band edges but also X- p states contributing to upper valence bands are localized by amorphization. The transitions from the localized Pb2+ 6s to 6p states produce the spin-orbit allowed 3P1 and dipole allowed 1P1 states responsible for the two Gaussians. The localized X- p states lie deeper in energy than the localized Pb2+ 6s state and only contribute to higher-energy absorption above the Gaussian bands, giving the reason for the reduced absorption near the fundamental edge. The blueshift of the optical energy gap is attributed to the disappearance of k dispersions for these one-electron states.
- Kondo,Sakai,Tanaka,Saito
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- Glass formation along the CsHgBr3-CsPbBr3, Cs 2HgBr4-CsPbBr3, and CsHg2Br 5-CsPbBr3 sections of the HgBr2-PbBr 2-CsBr ternary system
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Glass formation is studied along the CsHgBr3-CsPbBr3, Cs2HgBr4-CsPbBr3, and CsHg2Br 5-CsPbBr3 sections of the HgBr2-PbBr 2-CsBr ternary system. T
- Zaitseva,Kovaleva,Fedorov
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- Perovskite as Recyclable Photocatalyst for Annulation Reaction of N-Sulfonyl Ketimines
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A sustainable and cost-effective manner for the photocatalytic annulation reaction of N-sulfonyl ketimines with N-arylglycines to synthesize imidazolidine-fused sulfamidates (31 examples) by employing CsPbBr3 as a heterogeneous photocatalyst has been developed. The catalyst CsPbBr3 can be simply recovered from the reaction mixture and reused at least five times without an obvious reduction in its photocatalytic reactivity, exhibiting a high catalyst economic feature.
- Shi, Anzai,Sun, Kai,Chen, Xiaolan,Qu, Lingbo,Zhao, Yufen,Yu, Bing
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supporting information
p. 299 - 303
(2022/01/04)
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- Multi-dimensional collaborations boost lead halide perovskite driven superior and long-period CO2 photoreduction under liquid-phase H2O environment
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CsPbBr3 is considered as a promising photocatalyst owning to its excellent photoelectronic characteristics. However, the photocatalytic activity is still unsatisfactory due to its narrow light absorption range, weak electron reduction potential, and poor water-resistance. In this work, a three-dimensional porous melamine foam (MF) supported CsPbBr3?xIx was prepared via facile anti-solvent (isopropanol, IPA) and ion doping strategies, which successfully realize efficient photocatalytic CO2 reduction under liquid-phase H2O medium. The anti-solvent strategy enables uniform distribution of perovskite crystals on MF surface, which is beneficial to the increase of specific surface area and active sites. The iodine ion (I-) replacement can enhance light absorption and electron reduction capacity of CsPbBr3, contributing to the CO2 photoreduction. Under simulated solar irradiation, powdery CsPbBr3 exhibits no photocatalytic activity owing to its quick degradation in H2O medium. Interestingly, MF assisted perovskites presents the enhanced performance, with 195.97 μmol g?1?h?1 of product yield for CsPbBr2I (IPA), which is 22.0 times higher than that of MF/CsPbBr3. Moreover, the excellent photothermal recoverable effect and surface hydrophobicity of MF/CsPbBr2I (IPA) result in a long-period and stable photocatalytic CO2 reduction with no evident decrease of photocatalytic activity during 42 h.
- Chen, Qiao,Lan, Xuefang,Qi, Beining,Ren, Chunyan,Shi, Jinsheng
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- Molecular engineering of s-triazine and its derivatives applied in surface modification strategy for enhancing photoelectric performance of all-inorganic perovskites
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We develop the effective modification strategy based on molecular engineering of s-triazine and its derivatives to improve the photoelectric performance of all-inorganic perovskites (AIP) for the first time. The surface modification strategy with cyanuric
- Yue, Yifei,Liu, Shengnan,Zhang, Ning,Su, Zhongmin,Zhu, Dongxia
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supporting information
p. 547 - 550
(2021/08/18)
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- Performance enhancement of CsPbBr3 thin film-based light-emitting diodes by CsF-induced surface modification
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Metal halide perovskites have been an attractive optoelectronic material for light-emitting diodes (LEDs) and display applications as well as photovoltaic devices. However, poor device performance and operation stability still impede their development and application. This paper reports a facile surface modification method to enhance the performance of CsPbBr3 thin film-based LEDs using CsF with various molar contents. Structural and chemical investigations showed that the CsF treatment removes the surface pinhole defects and fluorinates the CsPbBr3 surface simultaneously, which resulted in the enhanced photoluminescence intensity compared to the pristine one. The CsF treatment enhanced the LED performance by increasing the electroluminescence intensity while mitigating the saturation behavior, even under high applied bias. These outcomes were attributed to the advantageous roles of the CsF treatment, i.e., removal of surface pinhole defects, passivation of surface non-radiative defects, and the formation of an electron blocking layer.
- Cho, Joon-Bum,Cho, Seung-Bum,Park, Il-Kyu
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- Photogeneration of thiyl radicals using metal-halide perovskite for highly efficient synthesis of thioethers
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Recently, the use of metal-halide perovskite (MHP) for photoinduced organics transformation has attracted much attention. We report herein the development of photoinduced thiol-ene reaction using inorganic MHP of CsPbBr3 nanocrystal that is visible light-responsive, easy-to-prepare, and cost-effective. Under blue light-emitting diode (LED), a series of thiol substrates are demonstrated to be highly efficient reaction partners to couple with alkenes tolerated with various functional groups, affording diverse thioethers containing C–S bonds. The CsPbBr3-mediated thiol-ene reaction is characterized by high efficiency, broad substrate applicability, excellent yields, and mild conditions. Mechanism investigation shows that the visible light-excited CsPbBr3 induces the generation of thiyl radicals via hole oxidation to initiate the reaction, followed by redox neutral pathway and/or chain transfer pathway to accomplish thiol–olefin coupling. It is notable that CsPbBr3 exhibits advanced thiol-ene performance than that using MHP analogs and others. The work presents a new exploration of MHP-mediated transformation and shows great potential of MHPs for radical chemistry.
- Liu, Xin,Bai, Rong,Guo, Zhifen,Che, Yan,Guo, Chunyi,Xing, Hongzhu
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- Direct deposition of Sn-doped CsPbBr3perovskite for efficient solar cell application
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All inorganic carbon-based planar perovskites, particularly CsPbBr3, have attracted considerable attention due to their excellent stability against oxygen, moisture, and heat for photovoltaic utilization. However, the power conversion efficiency of carbon-based planar CsPbBr3 perovskite solar cells is mostly low, primarily because of the inferior film quality with undesirable crystallization and narrow light absorbance ranges. Herein, we develop a novel direct deposition approach combined with Sn doping to achieve highly efficient and stable carbon-based Sn-doped CsPbBr3 perovskite solar cells. Mass-scale Sn ion-doped CsPbBr3 perovskite powder was effectively synthesized and characterized via a facile strategy by adding hydrohalic acid in the CsBr, PbBr2 and SnBr2 precursor in a dimethyl sulfoxide solution. Moreover, using the as-synthesized CsPbBr3 and Sn-doped CsPbBr3 perovskite powder, PSCs were obtained via effective direct thermal evaporation. A smooth, constant and pinhole-free perovskite film was achieved with a configuration of FTO/TiO2/Sn:CsPbBr3/carbon. PSCs based on Sn:CsPbBr3 as an absorber and carbon as the HTM achieved an impressive power conversion efficiency of 8.95% compared to 6.87% for undoped CsPbBr3; moreover, it displayed admirable stability in an open-air atmosphere for an operational period of about 720 h without a noticeable negative result. The introduction of the Sn ion may advance the interface extraction of charge between the electric transport layer to the absorber layer and absorber to the carbon electrode. Accordingly, the Sn ion doping on CsPbBr3 during the synthesis phase and the direct evaporation paves a novel approach for intended photovoltaic applications.
- Abib, Mukerem Helil,Li, Junchun,Yang, Heming,Wang, Man,Chen, Taotao,Enzexu,Jiang, Yang
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p. 3380 - 3389
(2021/02/03)
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- Role of the A-Site Cation in Low-Temperature Optical Behaviors of APbBr3(A = Cs, CH3NH3)
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APbBr3 (A = Cs, CH3NH3) are prototype halide perovskites having bandgaps of 2.30-2.35 eV at room temperature, rendering their apparent color nearly identical (bright orange but opaque). Upon optical excitation, they emit bright photoluminescence (PL) arising from carrier recombination whose spectral features are also similar. At 10 K, however, the apparent color of CsPbBr3 becomes transparent yellow, whereas that of CH3NH3PbBr3 does not change significantly due to the presence of an indirect Rashba gap. With increasing the excitation level, evolution of the PL spectra, which are excitonic at 10 K, reveals the emergence of P-band emission arising from inelastic exciton-exciton scattering. Based on the spectral location of the P-band, exciton binding energies are determined to be 21.6 ± 2.0 and 38.3 ± 3.0 meV for CsPbBr3 and CH3NH3PbBr3, respectively. Intriguingly, upon further increase in the exciton density, electron-hole plasma appears in CsPbBr3 as evidenced by both red-shift and broadening of the PL. This phase, however, does not occur in CH3NH3PbBr3 presumably due to polaronic effects. Although the A-site cation is believed not to directly impact optical properties of APbBr3, our results underscore its critical role, which destines different high-density phases and apparent color at low temperatures.
- Ryu, Hongsun,Byun, Hye Ryung,McCall, Kyle M.,Park, Dae Young,Kim, Tae Jung,Jeong, Mun Seok,Kanatzidis, Mercouri G.,Jang, Joon I.
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supporting information
p. 2340 - 2347
(2021/02/16)
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- Vibrational study of lead bromide perovskite materials with variable cations based on Raman spectroscopy and density functional theory
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Metal halide-based perovskite semiconductors exhibit excellent optoelectronic properties such as a sharp absorption edge, high absorption coefficients, and a small recombination rate. Mixed compositions result in a variation of the structure of these perovskite materials, which also influences their electronic properties. Even though huge progress in synthesis and device fabrication has been made, still systematic investigations of structural properties of lead halide-based perovskites are missing. Here, we systematically investigate the vibrational features of lead bromide-based perovskites using Raman spectroscopy and density functional theory (DFT). We have performed these investigations using MA+, FA+, and Cs+ as cations in the lead bromide structures and determined the vibrational modes both from Raman experiments and DFT simulations. We find a clear dependence of the Raman band wavenumbers on the chosen cations. The structural differences are reflected in the different line-width broadening of Raman bands, charge distribution on the cations and the extent of their interactions with the bromide anions.
- Ghosh, Supriya,Rana, Debkumar,Pradhan, Bapi,Donfack, Patrice,Hofkens, Johan,Materny, Arnulf
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p. 2338 - 2347
(2021/05/24)
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- Dibromo quaternary ammonium salt ligand and synthesis method for lead halide perovskite nanocrystalline solution
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The invention discloses a dibromo quaternary ammonium salt ligand and a synthesis method for a lead halide perovskite nanocrystalline solution, and relates to nanocrystalline synthesis. The dibromo quaternary ammonium salt ligand is used as a ligand for synthesis, and the preparation method comprises the following steps: 1) mixing at least one of cesium halide, formamidine halide and methylamine halide with lead halide and N, N-dimethylformamide according to a ratio, then carrying out ultrasonic dispersion, and putting at room temperature for later use; (2) adding a dibromo quaternary ammonium salt ligand into the solution obtained in the step (1), and carrying out ultrasonic dispersion; and (3) injecting the solution obtained in the step (2) into a toluene solution to synthesize a lead halide perovskite nanocrystalline solution. The prepared lead halide perovskite nanocrystal has high fluorescence quantum efficiency (more than 90%) and excellent stability, and is beneficial to future display and illumination application. The method has the advantages of simple operation, no inert atmosphere protection and heating treatment, easily available raw materials, and easy large-scale popularization and application.
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Paragraph 0021-0031
(2021/11/26)
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- Green solvent assisted preparation of one-dimensional CsPbBr3nanocrystals with a controllable morphology for cyan-emitting applications
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The ligand assisted reprecipitation (LARP) approach is a convenient method for synthesizing CsPbX3 NCs at room temperature. However, several remaining challenges limit its further development, such as the utilization of toxic solvents and fast crystallization brings colloidal uncontrollable synthesis issues. In this work we apply the principles of green chemistry to the LARP technique for synthesizing CsPbBr3 NCs under ambient conditions in a controllable way. Through the variation of non-toxic ester solvents with different polarity and reaction time, we demonstrate the size tunability of one-dimensional (1D) CsPbBr3 nanocrystals synthesized in a green solvent system. Due to the strong quantum confinement effect, the obtained CsPbBr3 NCs exhibited a wide photoluminescence emission (471-508 nm) and high quantum yield up to 78%. Interpretations on the related growth mechanism of CsPbBr3 nanocrystals in a polarity-mediated solution are suggested for exploring effective strategies towards high-quality inorganic perovskite nanocrystals with definite morphologies. Finally, to explore the potential applications of CsPbBr3 in white light-emitting diodes (WLEDs), cyan emission of CsPbBr3 NCs (480 nm) is combined with blue, green, and red emissions from commercial powders to achieve white light with excellent vision performance. The device displays a super high color rendering index of 96.5. This journal is
- Han, Xiuxun,Lai, Wenwei,Li, Wenhui,Wu, Chuanli
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p. 7805 - 7812
(2021/12/02)
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- A novel scintillation screen for achieving high-energy ray detection with fast and full-color emission
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Traditional inorganic scintillation crystals have a high stopping power to high-energy particles or rays; however, their wide applications are limited due to the fixed emission band. CsPbX3(X = Cl, Br, I) perovskite nanocrystals (CsPbX3NCs) have been proved to achieve full-color emission and effective X-ray detection, but failed to detect γ-rays effectively due to their weak absorption ability. Therefore, based on the advantages of the tunable spectra for CsPbX3NCs and the high stopping ability of a BaF2single crystal, a novel CsPbX3NCs@BaF2scintillation screen is developed ingeniously for realizing fast and full-color emission under high-energy ray excitation. The CsPbX3NCs@BaF2scintillation screen exhibits a tunable emission ranging from 435 to 648 nm under hard X-ray excitation. It is of note that the light yield of the CsPbBr3NCs@BaF2scintillation screen can reach up to 6300 photons per MeV and it shows a fast decay time component (~11 ns) under γ-ray excitation. The purpose of this contribution is to provide a new solution for guiding the perovskite materials as potential scintillators for fast and full-color emission expanding the application of high-energy radiation detection.
- Chen, Junfeng,Li, Huihui,Li, Qianli,Liu, Yufeng,Wang, Sheng,Yang, Heng,Yuan, Rui,Zhang, Zhijun,Zhao, Jingtai
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p. 7905 - 7909
(2021/07/06)
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- High Color Purity and Efficient Green Light-Emitting Diode Using Perovskite Nanocrystals with the Size Overly Exceeding Bohr Exciton Diameter
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Lead halide perovskite nanocrystals (PNCs) are emerging as promising light emitters to be actively explored for high color purity and efficient light-emitting diodes. However, the most reported lead halide perovskite nanocrystal light-emitting diodes (PNCLEDs) encountered issues of emission line width broadening and operation voltage elevating caused by the quantum confinement effect. Here, we report a new type of PNCLED using large-size CsPbBr3 PNCs overly exceeding the Bohr exciton diameter, achieving ultranarrow emission line width and rapid brightness rise around the turn-on voltage. We adopt calcium-tributylphosphine oxide hybrid ligand passivation to produce highly dispersed large-size colloidal CsPbBr3 PNCs with a weak size confinement effect and also high photoluminescence quantum yield (~85%). Utilizing these large-size PNCs as emitters, we manifest that the detrimental effects caused by the quantum confinement effect can be avoided in the device, thereby realizing the highest color purity in green PNCLED, with a narrow full width at half-maximum of 16.4 nm and a high corrected maximum external quantum efficiency of 17.85%. Moreover, the operation half-life time of the large-size PNCLED is 5-fold of that based on smaller-size PNCs. Our work provides a new avenue for improving the performance of PNCLEDs based on unconventional large-size effects.
- Chen, Tian,Ge, Jing,Lan, Yi-Feng,Ma, Zhen-Yu,Ru, Xue-Chen,Wang, Jing-Jing,Yang, Jun-Nan,Yao, Hong-Bin,Yin, Yi-Chen,Zhang, Qun
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- Core-shell CsPbBr3@Cs4PbBr6 nanocrystals dispersed in thermoplastic polyurethane as writeable heat-resistant fluorescent inks
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The cesium lead halide perovskites CsPbX3 (X = Cl, Br, I) have received extensive attention in the solar cell and light-emitting devices owing to their excellent optical and electronic properties. However, in practical applications, CsPbX3 often suffers from many disturbances caused by changes in the external environment, which will weaken its performance. In order to better solve this issue, a series of encapsulation strategies have been proposed to protect the stability of CsPbX3. In particular, the derivative Cs4PbX6 of CsPbX3 was well received as a shell protective material because it does not introduce new elements. Here, we prepared large-yield stable CsPbBr3@Cs4PbBr6 core-shell nanocrystals (NCs) by adjusting the initial ratio of Cs/Pb using one-pot route. At the same time, the growth process of CsPbBr3@Cs4PbBr6 NCs were analyzed, and their stability was evaluated under atmospheric conditions. The results show that CsPbBr3@Cs4PbBr6 NCs exhibit excellent stability compared to the pure phase CsPbBr3 NCs, and thus the passivation of Cs4PbBr6 to CsPbBr3 was obtained. Subsequently, a writable fluorescent ink by mixing CsPbBr3@Cs4PbBr6 NCs and thermoplastic polyurethane (TPU) was developed, which held excellent heat-resistance stability under multiple heating-cooling cycles. Our research will greatly simplify the preparation process of stabilized CsPbBr3@Cs4PbBr6 core-shell NCs and provide alternative options for the commercial development of perovskite materials.
- Ge, Wanyin,Shi, Jindou,Tian, Ye,Xu, Meimei,Wu, Yuanting,Li, Yongxiang
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- A Nanocrystal Catalyst Incorporating a Surface Bound Transition Metal to Induce Photocatalytic Sequential Electron Transfer Events
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Heterogeneous photocatalysis is less common but can provide unique avenues for inducing novel chemical transformations and can also be utilized for energy transductions, i.e., the energy in the photons can be captured in chemical bonds. Here, we developed a novel heterogeneous photocatalytic system that employs a lead-halide perovskite nanocrystal (NC) to capture photons and direct photogenerated holes to a surface bound transition metal Cu-site, resulting in a N-N heterocyclization reaction. The reaction starts from surface coordinated diamine substrates and requires two subsequent photo-oxidation events per reaction cycle. We establish a photocatalytic pathway that incorporates sequential inner sphere electron transfer events, photons absorbed by the NC generate holes that are sequentially funneled to the Cu-surface site to perform the reaction. The photocatalyst is readily prepared via a controlled cation-exchange reaction and provides new opportunities in photodriven heterogeneous catalysis.
- Martin, Jovan San,Zeng, Xianghua,Chen, Xihan,Miller, Collin,Han, Chuang,Lin, Yixiong,Yamamoto, Nobuyuki,Wang, Xiaoming,Yazdi, Sadegh,Yan, Yanfa,Beard, Matthew C.,Yan, Yong
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supporting information
p. 11361 - 11369
(2021/08/16)
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- Dimensionality Control of Inorganic and Hybrid Perovskite Nanocrystals by Reaction Temperature: From No-Confinement to 3D and 1D Quantum Confinement
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This work focuses on the systematic investigation of the shape, size, and composition-controlled synthesis of perovskite nanocrystals (NCs) under inert gas-free conditions and using pre-synthesized precursor stock solutions. In the case of CsPbBr3 NCs, we find that the lowering of reaction temperature from ~175 to 100 °C initially leads to a change of morphology from bulk-like 3D nanocubes to 0D nanocubes with 3D-quantum confinement, while at temperatures below 100 °C the reaction yields 2D nanoplatelets (NPls) with 1D-quantum confinement. However, to our surprise, at higher temperatures (~215 °C), the reaction yields CsPbBr3 hexapod NCs, which have been rarely reported. The synthesis is scalable, and their halide composition is tunable by simply using different combinations of precursor solutions. The versatility of the synthesis is demonstrated by applying it to relatively less explored shape-controlled synthesis of FAPbBr3 NCs. Despite the synthesis carried out in the air, both the inorganic and hybrid perovskite NCs exhibit nearly-narrow emission without applying any size-selective separation, and it is precisely tunable by controlling the reaction temperature.
- García-Lojo, Daniel,Otero-Martínez, Clara,Pérez-Juste, Jorge,Pastoriza-Santos, Isabel,Polavarapu, Lakshminarayana
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supporting information
p. 26677 - 26684
(2021/11/23)
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- PEROVSKITES FOR PHOTOCATALYTIC ORGANIC SYNTHESIS
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Nature is capable of storing solar energy in chemical bonds via photosynthesis through a series of C—C, C—O and C—N bond-forming reactions starting from CO2 and light. Direct capture of solar energy for organic synthesis is a promising approach
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Paragraph 0100
(2022/01/07)
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- DETECTION OF HALOCARBONS
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Disclosed herein is a sensor apparatus or system to determine the presence of a halocarbon in a sample, the sensor apparatus or system comprising: a structure for receiving the sample and contacting the sample with a reagent, the reagent reactive with the halocarbon to release a halide anion; a sensor comprising a crystalline material having an anion component suitable for undergoing passivation and/or anion exchange with the halide ion, the crystalline material exhibiting a detectable difference in spectral properties before and after passivation and/or anion exchange; and a detector for detecting the difference in spectral properties, the difference in spectral properties indicative of the presence of the halide anion. Also disclosed herein are methods to determine the presence of a halocarbon in a sample.
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Paragraph 00081
(2021/03/19)
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- Chemical vapor deposition growth of phase-selective inorganic lead halide perovskite films for sensitive photodetectors
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Inorganic lead halide perovskites are attractive optoelectronic materials owing to their relative stability compared to organic cation alternatives. The chemical vapor deposition (CVD) method offers potential for high quality perovskite film growth. The deposition temperature is a critical parameter determining the film quality owing to the melting difference between the precursors. Here, perovskite films were deposited by the CVD method at various temperatures between 500?800 °C. The perovskite phase converts from CsPb2Br5 to CsPbBr3 gradually as the deposition temperature is increased. The grain size of the perovskite films also increases with temperature. The phase transition mechanism was clarified. The photoexcited state dynamics were investigated by spatially and temporally resolved fluorescence measurements. The perovskite film deposited under 750 °C condition is of the CsPbBr3 phase, showing low trap-state density and large crystalline grain size. A photodetector based on perovskite films shows high photocurrent and an on/off ratio of ~2.5 × 104.
- Xu, Weilong,Niu, Mengsi,Yang, Xiaoyu,Chen, Haiyue,Cai, Xiaohong,Smith, Trevor A.,Ghiggino, Kenneth P.,Hao, Xiaotao
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supporting information
p. 489 - 492
(2020/07/07)
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- Coupling CsPbBr3 Quantum Dots with Covalent Triazine Frameworks for Visible-Light-Driven CO2 Reduction
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Photocatalytic reduction of CO2 into value-added chemical fuels is an appealing approach to address energy crisis and global warming. CsPbBr3 quantum dots (QDs) are good candidates for CO2 reduction because of their excellent photoelectric properties, including high molar extinction coefficient, low exciton binding energy, and defect tolerance. However, the pristine CsPbBr3 QDs generally have low photocatalytic performance mainly due to dominant charge recombination and lack of efficient catalytic sites for CO2 adsorption/activation. Herein, we report a new photocatalytic system, in which CsPbBr3 QDs are coupled with covalent triazine frameworks (CTFs) for visible-light-driven CO2 reduction. In this hybrid photocatalytic system, the robust triazine rings and periodical pore structures of CTFs promote the charge separation in CsPbBr3 and endow them with strong CO2 adsorption/activation capacity. The resulting photocatalytic system exhibits excellent photocatalytic activity towards CO2 reduction. This work presents a new photocatalytic system based on CTFs and perovskite QDs for visible-light-driven CO2 reduction, which highlights the potential of perovskite-based photocatalysts for solar fuel applications.
- Wang, Qi,Wang, Jin,Wang, Ji-Chong,Hu, Xin,Bai, Yu,Zhong, Xinhua,Li, Zhengquan
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p. 1131 - 1139
(2021/01/12)
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- Construction of a CsPbBr3modified porous g-C3N4photocatalyst for effective reduction of CO2and mechanism exploration
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In-depth research of the active sites and charge transport behavior is an important topic for investigating photocatalytic reduction of CO2. Herein, a novel photocatalyst composed of flake-like porous graphitic carbon nitride (P-CN) and CsPbBr3 is fabricated via a high temperature calcination and freeze drying method. The experimental results show that P-CN/CsPbBr3 has a superior CO2 reduction efficiency, and that the yield of CO reaches 30.39 μmol g-1, which is about 7.2 and 1.2 times higher than those of the primary B-CN (4.2 μmol g-1) and CsPbBr3 (24.4 μmol g-1), respectively. The improvement in photocatalytic performance is mainly ascribed to the heterostructure, which can promote the separation of photogenerated carriers, and the porous structure of P-CN, which can improve the absorption capacity of CO2. This study provides a significant method for the construction of efficient g-C3N4 based photocatalysts to reduce CO2.
- Wang, Yunqi,Liu, Zhixiang,Tang, Xu,Huo, Pengwei,Zhu, Zhi,Yang, Boting,Liu, Zhi
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p. 1082 - 1091
(2021/01/25)
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- Perovskite Quantum Dots Encapsulated in a Mesoporous Metal-Organic Framework as Synergistic Photocathode Materials
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Metal halide perovskite quantum dots, with high light-absorption coefficients and tunable electronic properties, have been widely studied as optoelectronic materials, but their applications in photocatalysis are hindered by their insufficient stability because of the oxidation and agglomeration under light, heat, and atmospheric conditions. To address this challenge, herein, we encapsulated CsPbBr3 nanocrystals into a stable iron-based metal-organic framework (MOF) with mesoporous cages (~5.5 and 4.2 nm) via a sequential deposition route to obtain a perovskite-MOF composite material, CsPbBr3@PCN-333(Fe), in which CsPbBr3 nanocrystals were stabilized from aggregation or leaching by the confinement effect of MOF cages. The monodispersed CsPbBr3 nanocrystals (4-5 nm) within the MOF lattice were directly observed by transmission electron microscopy and corresponding mapping analysis and further confirmed by powder X-ray diffraction, infrared spectroscopy, and N2 adsorption characterizations. Density functional theory calculations further suggested a significant interfacial charge transfer from CsPbBr3 quantum dots to PCN-333(Fe), which is ideal for photocatalysis. The CsPbBr3@PCN-333(Fe) composite exhibited excellent and stable oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activities in aprotic systems. Furthermore, CsPbBr3@PCN-333(Fe) composite worked as the synergistic photocathode in the photoassisted Li-O2 battery, where CsPbBr3 and PCN-333(Fe) acted as optical antennas and ORR/OER catalytic sites, respectively. The CsPbBr3@PCN-333(Fe) photocathode showed lower overpotential and better cycling stability compared to CsPbBr3 nanocrystals or PCN-333(Fe), highlighting the synergy between CsPbBr3 and PCN-333(Fe) in the composite.
- Qiao, Guan-Yu,Guan, Dehui,Yuan, Shuai,Rao, Heng,Chen, Xiao,Wang, Jia-Ao,Qin, Jun-Sheng,Xu, Ji-Jing,Yu, Jihong
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supporting information
p. 14253 - 14260
(2021/09/13)
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- The synergy between the CsPbBr3nanoparticle surface and the organic ligand becomes manifest in a demanding carbon-carbon coupling reaction
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We demonstrate here the suitability of CsPbBr3nanoparticles as photosensitizers for a demanding photoredox catalytic homo- and cross-coupling of alkyl bromides at room temperature by merely using visible light and an electron donor, thanks to the cooperative action between the nanoparticle surface and organic capping.
- Casadevall, Carla,Claros, Miguel,Galian, Raquel E.,Lloret-Fillol, Julio,Pérez-Prieto, Julia,Rosa-Pardo, Ignacio,Schmidt, Luciana
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supporting information
p. 5026 - 5029
(2020/05/18)
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- TUNABLE BLUE EMITTING LEAD HALIDE PEROVSKITES
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The invention relates to perovskite compounds which have surprisingly good emission properties, particularly photoluminescent emission properties, in the blue region of the visible spectrum. These perovskites contain a mixture of cations or a mixture of halides, or both. The invention also relates to a photoactive material containing the perovskite species of the invention; to an optoelectronic device containing the photoactive material of the invention; to a method of producing blue light; and to the use of the photoactive material of the invention to emit blue light or as a phosphor.
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Page/Page column 64
(2020/02/06)
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- Enhancing Carrier Transport Properties of Melt-grown CsPbBr3 Single Crystals by Eliminating Inclusions
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All-inorganic perovskite CsPbBr3 has attracted intense attentions due to its inspiring optoelectronic properties and excellent stability. Growing large-size single crystals with high quality is vital both for the intrinsic property investigation and the high-performance device fabrication. Here, large-size CsPbBr3 single crystals (φ 30 mm × 100 mm) were grown by the modified Bridgman method. The surface morphologies of the as-grown CsPbBr3 single-crystal wafers were characterized by SEM, and inclusions with size of 1-2 μm were observed in the first-time grown crystal (labeled as CPB-1). By adopting a slower growth rate (0.2 mm/h) and cooling rate (5 °C/h) than that of CPB-1, the inclusions were eliminated in subsequent growth (labeled as CPB-2). The hole mobility-lifetime products were measured to be 3.92 × 10-3 and 1.46 × 10-2 cm2·V-1 for CPB-1 and CPB-2, respectively. The carrier mobility of CPB-2 was enhanced 1 order of magnitude from 10.1 ± 0.3 cm2·V-1·s-1 (CPB-1) to 101.3 ± 4.2 cm2·V-1·s-1 due to the elimination of inclusions. In addition, CPB-2 exhibited excellent α particles detection ability with the optimal energy resolution of 15.1% at -60 V bias. We provide an effective way to enhance the optoelectronic properties and device performance of melt-grown CsPbBr3 single crystal by preventing the formation of the inclusions.
- Li, Xiang,Liu, Lin,Sun, Qihao,Tao, Xutang,Xu, Yadong,Zhang, Guodong,Zhang, Peng
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p. 2424 - 2431
(2020/04/28)
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- High-Performance Perovskite Light-Emitting Diode with Enhanced Operational Stability Using Lithium Halide Passivation
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Defect passivation has been demonstrated to be effective in improving the radiative recombination of charge carriers in perovskites, and consequently, the device performance of the resultant perovskite light-emitting diodes (LEDs). State-of-the-art useful passivation agents in perovskite LEDs are mostly organic chelating molecules that, however, simultaneously sacrifice the charge-transport properties and thermal stability of the resultant perovskite emissive layers, thereby deteriorating performance, and especially the operational stability of the devices. We demonstrate that lithium halides can efficiently passivate the defects generated by halide vacancies and reduce trap state density, thereby suppressing ion migration in perovskite films. Efficient green perovskite LEDs based on all-inorganic CsPbBr3 perovskite with a peak external quantum efficiency of 16.2 %, as well as a high maximum brightness of 50 270 cd m?2, are achieved. Moreover, the device shows decent stability even under a brightness of 104 cd m?2. We highlight the universal applicability of defect passivation using lithium halides, which enabled us to improve the efficiency of blue and red perovskite LEDs.
- Bai, Sai,Duhm, Steffen,Gao, Feng,Li, Junnan,McLeod, John A.,Song, Tao,Sun, Baoquan,Wan, Shanshan,Wen, Kaichuan,Wu, Tian,Xu, Hao,Zou, Yatao
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supporting information
p. 4099 - 4105
(2020/02/04)
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- Static Rashba Effect by Surface Reconstruction and Photon Recycling in the Dynamic Indirect Gap of APbBr3(A = Cs, CH3NH3) Single Crystals
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Recently, halide perovskites have gained significant attention from the perspective of efficient spintronics owing to the Rashba effect. This effect occurs as a consequence of strong spin-orbit coupling under a noncentrosymmetric environment, which can be dynamic and/or static. However, there exist intense debates on the origin of broken inversion symmetry since the halide perovskites typically crystallize into a centrosymmetric structure. In order to clarify the issue, we examine both dynamic and static effects in the all-inorganic CsPbBr3 and organic-inorganic CH3NH3PbBr3 (MAPbBr3) perovskite single crystals by employing temperature- and polarization-dependent photoluminescence excitation spectroscopy. The perovskite single crystals manifest the dynamic effect by photon recycling in the indirect Rashba gap, causing dual peaks in the photoluminescence. However, the effect vanishes in CsPbBr3 at low temperatures (a striking color change of the crystal, arising presumably from lower degrees of freedom for inversion symmetry breaking associated with the thermal motion of the spherical Cs cation compared with the polar MA cation in MAPbBr3. We also show that the static Rashba effect occurs only in MAPbBr3 below 90 K, presumably due to surface reconstruction via MA-cation ordering, which likely extends across a few layers from the crystal surface to the interior. We further demonstrate that this static Rashba effect can be completely suppressed upon surface treatment with polymethyl methacrylate (PMMA) coating. We believe that our results provide a rationale for the Rashba effects in halide perovskites.
- Ryu, Hongsun,Park, Dae Young,McCall, Kyle M.,Byun, Hye Ryung,Lee, Yongjun,Kim, Tae Jung,Jeong, Mun Seok,Kim, Jeongyong,Kanatzidis, Mercouri G.,Jang, Joon I.
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supporting information
p. 21059 - 21067
(2020/12/23)
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- Composition related structural transition between mechanosynthesized CsPbBr3 and CsPb2Br5 perovskites and their optical properties
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A facile solvent-free mechanochemical synthesis mechanism of perovskites of Cs–Pb–Br system has been demonstrated in the present study. Inherent structural and microstructural characteristics of CsPbBr3 and CsPb2Br5 perovskites are investigated by analyzing powder XRD patterns using Rietveld refinement analysis and formation of these perovskites has been ascertained. The compositional phase transition between orthorhombic CsPbBr3 and tetragonal CsPb2Br5 perovskites has been explained from the structural point of view. The optically active orthorhombic CsPbBr3 perovskite transforms to optically inactive tetragonal CsPb2Br5 perovskite under flowing water vapour within a short duration and the reverse transformation is noticed when the tetragonal perovskite is heat-treated at elevated temperature. Optical properties of these perovskites corroborate well with structural phase transitions of these compounds. This new approach of structural conversion not only provides a controlled synthesis of the ternary Cs–Pb–Br system but also demonstrates a clear underlying mechanism for the structural instability and associated optical properties.
- Maity,Pradhan
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- Stable and Monochromatic All-Inorganic Halide Perovskite Assisted by Hollow Carbon Nitride Nanosphere for Ratiometric Electrochemiluminescence Bioanalysis
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Lead halide perovskites have been promising electrochemiluminescence (ECL) candidates because of their excellent photophysical attributes, but their poor stability has severely restricted ECL applications. Herein, the in situ assembly of all-inorganic perovskite CsPbBr3 nanocrystals (CPB) into hollow graphitic carbon nitride nanospheres (HCNS) were described as a novel ECL emitter. The architecture guaranteed not only improved stability because of the peripheral HCNS protecting shell but also high-performance ECL of CPB because of a matching band-edge arrangement. Dual-ECL readouts were obtained from the nanocomposite including an anodic ECL from CPB and a cathodic ECL from HCNS. The former displayed prominent color purity to construct an efficient ECL resonance energy transfer system, and the latter served as an internal standard for a ratiometric analysis. A well-designed DNA probe was further utilized for the targeting of CD44 receptors on the MCF-7 cell surface and the double signal amplification. The sensing strategy exhibited good analytical performance for MCF-7 cells, ranging from 1.0 × 103 to 3.2 × 105 cells mL-1 with a detection limit of 320 cells mL-1. Sensitive and accurate evaluation of CD44 expression was finally achieved at 0.22 pM. This work is the first attempt to use halide perovskite for reliable ECL bioanalysis and provides a perspective to design a perovskite-based nanocomposite as a high-performance ECL emitter for its exclusive ECL system.
- Cao, Yue,Lin, Yuehe,Ma, Cheng,Wei, Huifang,Zhu, Jun-Jie,Zhu, Wenlei
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- The cation-anion co-exchange in CsPb1?xFex(Br1?yCly)3nanocrystals prepared using a hot injection method
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All inorganic perovskite nanocrystals (NCs) have wide practical applications for their remarkable optoelectronic properties. To obtain blue-emitting perovskites with high photoluminescence quantum yield and room-temperature ferromagnetism, CsPb1?xFex(Br1?yCly)3NCs were synthesized using a hot injection method. The effects of the cation-anion co-exchange on the structural, luminescent and magnetic properties of CsPbBr3NCs were studied by X-ray diffraction spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, and vibrating sample magnetometer. The results indicated that there was cation-anion co-exchange in CsPb1?xFex(Br1?yCly)3NCs, while the band-edge energies and PLQY were mainly affected by the anion exchange. The ferromagnetism of CsPb1?xFex(Br1?yCly)3NCs had been observed at room temperature, and there was an increase in saturation magnetization with increasing Fe concentration.
- Hu, Yue,Li, Ji,Wang, Li,Yang, Chaoqun,Zhang, Yuxin
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p. 33080 - 33085
(2020/09/21)
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- In situ synthesis of high-efficiency CsPbBr3/CsPb2Br5composite nanocrystals in aqueous solution of microemulsion
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Here, we present the microemulsion method using sodium dodecylbenzenesulfonate and hydrofluoric acid for the in situ synthesis of brightly luminescent CsPbBr3/CsPb2Br5 composite nanocrystals (NCs) in aqueous solution. The obtained CsPbBr3/CsPb2Br5 composite NCs exhibit a photoluminescence quantum yield of 77.0% and a full width at half maximum of 16.0 nm. And solid-state back-lighting devices were fabricated by combining CsPbBr3/CsPb2Br5 composite NCs and red-emitting K2SiF6:Mn4+ phosphors with blue light. The as-fabricated device exhibits a wide color gamut of about 95.8% of the Rec. 2020. This work provides a green, low-cost, and in situ water-phase route to synthesize high-quality cesium lead halide NCs for their practical applications in solid-state back-lighting devices. This journal is
- Bao, Zhen,Cao, Luyu,Gan, Weijiang,Li, Huili,Liu, Ru-Shi,Lou, Sunqi,Qiu, Jianbei,Si, Shuaichen,Wang, Jing,Xia, Zhiguo,Xuan, Tongtong,Zhou, Zhi
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supporting information
p. 5257 - 5261
(2020/09/23)
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- Scaling Laws of Exciton Recombination Kinetics in Low Dimensional Halide Perovskite Nanostructures
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Carrier recombination is a crucial process governing the optical properties of a semiconductor. Although various theoretical approaches have been utilized to describe carrier behaviors, a quantitative understanding of the impact of defects and interfaces in low dimensional semiconductor systems is still elusive. Here, we develop a model system consisting of chemically tunable, highly luminescent halide perovskite nanocrystals to illustrate the role of carrier diffusion and material dimensionality on the carrier recombination kinetics and luminescence efficiency. Our advanced synthetic methods provide a well-controlled colloidal system consisting of nanocrystals with different aspect ratios, halide compositions, and surface conditions. Using this system, we reveal the scaling laws of photoluminescence quantum yield and radiative lifetime with respect to the aspect ratio of nanocrystals. The scaling laws derived herein are not only a phenomenological observation but proved a powerful tool disentangling the carrier dynamics of microscopic systems in a quantitative and interpretable manner. The investigation of our model system and theoretical formulation bring to light the dimensionality, as a hidden constraint on carrier dynamics, and identify the diffusion length as an important parameter that distinguishes nanoscale and macroscale carrier behaviors. The conceptual distinction in carrier dynamics in different dimensionality regimes informs new design rules for optical devices where complex microstructures are involved.
- Gao, Mengyu,Liu, Hao,Yu, Sunmoon,Louisia, Sheena,Zhang, Ye,Nenon, David P.,Alivisatos, A. Paul,Yang, Peidong
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supporting information
p. 8871 - 8879
(2020/12/23)
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- Room-temperature doping of ytterbium into efficient near-infrared emission CsPbBr1.5Cl1.5perovskite quantum dots
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Herein, we present a two-step method to dope various amounts of Yb into CsPbBr1.5Cl1.5QDs at room temperature. It is found that the CsPbBr1.5Cl1.5QDs can exhibit strong ~990 nm near-infrared (NIR light) emission, and the NIR photoluminescence quantum yield (PLQY) is able to reach ~90% when 10% Yb is doped in the CsPbBr1.5Cl1.5QDs.
- Zhao, Shuangyi,Zhang, Yubo,Zang, Zhigang
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supporting information
p. 5811 - 5814
(2020/06/03)
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- Rapid Capillary-Assisted Solution Printing of Perovskite Nanowire Arrays Enables Scalable Production of Photodetectors
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Despite recent progress in producing perovskite nanowires (NWs) for optoelectronics, it remains challenging to solution-print an array of NWs with precisely controlled position and orientation. Herein, we report a robust capillary-assisted solution printing (CASP) strategy to rapidly access aligned and highly crystalline perovskite NW arrays. The key to the CASP approach lies in the integration of capillary-directed assembly through periodic nanochannels and solution printing through the programmably moving substrate to rapidly guide the deposition of perovskite NWs. The growth kinetics of perovskite NWs was closely examined by in situ optical microscopy. Intriguingly, the as-printed perovskite NWs array exhibit excellent optical and optoelectronic properties and can be conveniently implemented for the scalable fabrication of photodetectors.
- Lan, Chuntao,Lian, Tianquan,Lin, Zhiqun,Liu, Qiliang,Pan, Shuang,Peng, Juan,Wang, Aurelia C.,Wang, Zewei,Wang, Zhong Lin,Yu, Jiwoo,Zou, Haiyang
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supporting information
p. 14942 - 14949
(2020/07/02)
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