- Design and synthesis of two conjugated semiconductors containing quinoidal cyclopentadithiophene core
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We report the design and synthesis of two conjugated semiconductors (QT and QP) with a quinoidal cyclopentadithiophene core through a simple method. X-ray single-crystal analysis provides detailed structure information such as molecular geometry, bond length alternation and solid packing motifs. The quinoidal character enables QT and QP with narrow bandgaps and strong absorption coefficients (>105 M?1 cm?1) in UV–Vis region. The charge transport properties of quinoidal semiconductor single crystals are investigated by organic field-effect transistors. QT achieves a hole mobility of 2.4 × 10?3 cm2/Vs while QP obtains a hole mobility of 6.9 × 10?4 cm2/Vs. The report of such type of quinoidal skeleton may provide useful guidance for constructing promising conjugated semiconductors for organic electronics.
- Wang, Kai,Li, Zheng,Huang, Jun,Wang, Tingting,Gao, Jiaxin,Gao, Yu,Wang, Shuojun,He, Shi,Lv, Aifeng,Wang, Ming
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- Synthetic routes to solution-processable polycyclopentadithiophenes
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Three synthetic protocols have been employed to prepare solution-processable poly(4,4-dialkylcyclopentadithiophenes). These polymers are fused-ring analogues of poly(3-alkylthiophenes) and structural analogues of the polyfluorenes. Oxidative polymerization of 4,4-dialkylcyclopenta[2,1-b;3,4-b]dithiophenes using iron (III) chloride gave high-molecular-weight polymers, whereas nickel-catalyzed polymerization of the 2,6-dibromo derivatives via in situ-generated thienylmagnesium and thienylzinc reagents gave moderate-molecular-weight polymers. The structures of the polymers were confirmed by NMR spectroscopy and MALDI-TOF mass spectrometry. In the polymerization using organomagnesium intermediates, some chain capping by methyl end groups was observed. This side reaction can be avoided by polymerization of the organozinc reagents. Post-functionalization of the halogen termini of these polymers can be readily achieved using a cross-coupling with an aryl Grignard reagent. The main chain conjugation in these polymers can be directly correlated to the length of the polymer backbone because the UV-vis spectra of fractionated samples show absorption maxima that increase with the average degree of polymerization as determined by GPC, up to a limiting value of ~20. UV-vis spectroscopy suggests that poly(4,4-dialkylcyclopentadithiophenes) do not self-assemble in the solid state, as has been previously observed for regioregular poly-3-alkylthiophenes.
- Coppo, Paolo,Cupertino, Domenico C.,Yeates, Stephen G.,Turner, Michael L.
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- Effects of alkyl chains on intermolecular packing and device performance in small molecule based organic solar cells
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Two donor molecules named as DR3TDTC-C6 and DR3TDTC-C8 with n-hexyl and n-octyl alkyl chains on the central building block 7H-cyclopenta-[1,2-b:3,4-b’]-dithiophene (DTC) were designed and synthesized. Both of them exhibited PCEs >4%. The photovoltaic properties of these molecules were superior to their analogous donor molecule DR3TDTC, which possess two 2-ethyl hexyl alkyl chains on the same core unit and only demonstrated a PCE of 0.75% after elaborative post-treatment. The influence of the alkyl chains on the optical, electrochemical properties, packing properties and morphology of these three molecules was systematically investigated. The results demonstrated that the difference between their device performances is mainly affected by their intermolecular packing state. This indicates that length and branch structure of alkyl chains on the central unit should be given careful consideration while designing donor molecules for small molecular organic solar cells.
- Zhang, Yamin,Li, Miaomiao,Feng, Huanran,Ni, Wang,Zhang, Hongtao,Liu, Feng,Wan, Xiangjian,Chen, Yongsheng
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- Dithienopyrrole as a rigid alternative to the bithiophene π relay in chromophores with second-order nonlinear optical properties
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4H-Pyranylidene-containing push-pull chromophores built around a bithiophene (BT) π relay or a rigidified thiophene-based unit, namely cyclopenta[1,2-b:3,4-b′]dithiophene (CPDT) or dithieno[3,2-b:2′,3′-d]pyrrole (DTP), have been synthesized and characterized. The effect of these different relays on the polarization and the second-order nonlinear optical (NLO) properties has been studied. For the sake of comparison, the corresponding reported dithieno[3,2-b:2′,3′-d]thiophene (DTT) derivatives have also been included in the discussion. Replacement of the BT core by a rigidified unit (CPDT, DTP) leads to more polarized systems. Calculated NBO charges and electrochemical measurements show that dithienopyrrole has a remarkable donor character that allows an important charge transfer between the donor and the acceptor. The influence of the rigidification of the BT relay on the NLO responses depends on the acceptor strength. For the weakest acceptor used (thiobarbituric acid), passing from the BT relay to the rigidified units always involves an increase in the μβ0 figure of merit. Nevertheless, for the strongest acceptor (2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF)), a slight increase in μβ0 with respect to the BT chromophore is only observed for the DTP derivative. Thus, rigidification of the BT core is not enough to improve the second-order nonlinearity and the incorporation of a DTP moiety has proven to be the most efficient approach for this purpose.
- Marco, A. Beln,De Baroja, Natalia Martnez,Franco, Santiago,Garn, Javier,Orduna, Jess,Villacampa, Beln,Revuelto, Alejandro,Andreu, Raquel
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- Indandione-Terminated Quinoids: Facile Synthesis by Alkoxide-Mediated Rearrangement Reaction and Semiconducting Properties
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A series of 1,3-indandione-terminated π-conjugated quinoids were synthesized by alkoxide-mediated rearrangement reaction of the respective alkene precursors, followed by air oxidation. This new protocol allows access to quinoidal compounds with variable termini and cores. The resulting quinoids all show LUMO levels below ?4.0 eV and molar extinction coefficients above 105 L mol?1 cm?1. The optoelectronic properties of these compounds can be regulated by tuning the central cores as well as the aryl termini ascribed to the delocalized frontier molecular orbitals over the entire molecular skeleton involving aryl termini. n-Channel organic thin-film transistors with electron mobility of up to 0.38 cm2 V?1 s?1 were fabricated, showing the potential of this new class of quinoids as organic semiconductors.
- Du, Tian,Gao, Ruiheng,Deng, Yunfeng,Wang, Cheng,Zhou, Qian,Geng, Yanhou
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- Searching for Models Exhibiting High Circularly Polarized Luminescence: Electroactive Inherently Chiral Oligothiophenes
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Two new inherently chiral oligothiophenes characterized by the atropisomeric 3,3′-bithianaphtene scaffold functionalized with fused ring bithiophene derivatives, namely 4H-cyclopenta[2,1-b3:4b′]dithiophene (CPDT) and dithieno[3,3-b:2′,3′-d]pyrrole (DTP), were synthesized. The racemates were fully characterized and resolved into antipodes by enantioselective HPLC. The enantiomers were analyzed through different chiroptical techniques: electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) were employed to attribute the absolute configuration (AC). Comparison of experimental and calculated VCD spectra confirmed the DFT calculated conformational characteristics. The compound functionalized with two CPDT units was oxidized with FeCl3, and ECD and CPL of the resulting material were measured. Circularly polarized luminescence (CPL) was measured to verify if inherently chiral oligothiophenes could be promising systems for chiral photonics applications.
- Benincori, Tiziana,Appoloni, Giulio,Mussini, Patricia Romana,Arnaboldi, Serena,Cirilli, Roberto,Quartapelle Procopio, Elsa,Panigati, Monica,Abbate, Sergio,Mazzeo, Giuseppe,Longhi, Giovanna
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p. 11082 - 11093
(2018/08/01)
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- Molecular engineering of face-on oriented dopant-free hole transporting material for perovskite solar cells with 19% PCE
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Through judicious molecular engineering, novel dopant-free star-shaped D-π-A type hole transporting materials coded KR355, KR321, and KR353 were systematically designed, synthesized and characterized. KR321 has been revealed to form a particular face-on organization on perovskite films favoring vertical charge carrier transport and for the first time, we show that this particular molecular stacking feature resulted in a power conversion efficiency over 19% in combination with mixed-perovskite (FAPbI3)0.85(MAPbBr3)0.15. The obtained 19% efficiency using a pristine hole transporting layer without any chemical additives or doping is the highest, establishing that the molecular engineering of a planar donor core, π-spacer and periphery acceptor leads to high mobility, and the design provides useful insight into the synthesis of next-generation HTMs for perovskite solar cells and optoelectronic applications.
- Rakstys, Kasparas,Paek, Sanghyun,Gao, Peng,Gratia, Paul,Marszalek, Tomasz,Grancini, Giulia,Cho, Kyung Taek,Genevicius, Kristijonas,Jankauskas, Vygintas,Pisula, Wojciech,Nazeeruddin, Mohammad Khaja
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p. 7811 - 7815
(2017/07/13)
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- Ligand Engineering for the Efficient Dye-Sensitized Solar Cells with Ruthenium Sensitizers and Cobalt Electrolytes
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Over the past 20 years, ruthenium(II)-based dyes have played a pivotal role in turning dye-sensitized solar cells (DSCs) into a mature technology for the third generation of photovoltaics. However, the classic I3-/I- redox couple limits the performance and application of this technique. Simply replacing the iodine-based redox couple by new types like cobalt(3+/2+) complexes was not successful because of the poor compatibility between the ruthenium(II) sensitizer and the cobalt redox species. To address this problem and achieve higher power conversion efficiencies (PCEs), we introduce here six new cyclometalated ruthenium(II)-based dyes developed through ligand engineering. We tested DSCs employing these ruthenium(II) complexes and achieved PCEs of up to 9.4% using cobalt(3+/2+)-based electrolytes, which is the record efficiency to date featuring a ruthenium-based dye. In view of the complicated liquid DSC system, the disagreement found between different characterizations enlightens us about the importance of the sensitizer loading on TiO2, which is a subtle but equally important factor in the electronic properties of the sensitizers.
- Aghazada, Sadig,Gao, Peng,Yella, Aswani,Marotta, Gabriele,Moehl, Thomas,Teuscher, Jo?l,Moser, Jacques-E.,De Angelis, Filippo,Gr?tzel, Michael,Nazeeruddin, Mohammad Khaja
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p. 6653 - 6659
(2016/07/19)
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- Highly efficient and facile alkylation of 4H-cyclopenta-[2,1-b:3,4- b′]dithiophene in water
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A new and highly convenient method to perform alkylation of 4H-cyclopenta-[2,1-b:3,4-b′]dithiophene (CPDT) in aqueous conditions is reported. This method was also extended to successfully perform alkylation of 2,6-dibromo-4H-cyclopenta-[2,1-b:3,4-b′]dithiophene for the first time. This facile method has several advantages such as the exclusive use of water instead of high boiling toxic solvents, simple separation of the defect free dialkylated CPDT product and the use of mild reaction conditions. Despite using mild reagents and reaction conditions, to our delight, very high yields of up to 98% pure dialkylated CPDT products are obtained much more readily by this method in less time than literature procedures. The isolated products were identified by HRMS and solution NMR measurements to be solely the desired dialkylated product with the alkyl halides used here. the Partner Organisations 2014.
- Raju, Telugu Bhim,Gopikrishna, Peddaboodi,Iyer, Parameswar Krishnan
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p. 37738 - 37745
(2014/11/08)
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- Highly efficient and facile alkylation of 4H-cyclopenta-[2,1-b:3,4-b′]dithiophene in water
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A new and highly convenient method to perform alkylation of 4H-cyclopenta-[2,1-b:3,4-b′]dithiophene (CPDT) in aqueous conditions is reported. This method was also extended to successfully perform alkylation of 2,6-dibromo-4H-cyclopenta-[2,1-b:3,4-b′]dithiophene for the first time. This facile method has several advantages such as the exclusive use of water instead of high boiling toxic solvents, simple separation of the defect free dialkylated CPDT product and the use of mild reaction conditions. Despite using mild reagents and reaction conditions, to our delight, very high yields of up to 98% pure dialkylated CPDT products are obtained much more readily by this method in less time than literature procedures. The isolated products were identified by HRMS and solution NMR measurements to be solely the desired dialkylated product with the alkyl halides used here. This journal is
- Raju, Telugu Bhim,Gopikrishna, Peddaboodi,Iyer, Parameswar Krishnan
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p. 37738 - 37745
(2015/02/19)
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- A versatile synthesis of long-wavelength-excitable BODIPY dyes from readily modifiable cyclopenta[2,1- B:3,4- B′ ]dithiophenes
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Knoevenagel condensation of a simple methylated borondipyrromethene (Bodipy) with 4,4′-dihexyl-4H-cyclopenta-[2,1-b:3,4-b′]dithiophenes functionalized at one end by a triphenylamine residue and at the other by a carbaldehyde fragment leads to novel dye species. These bisvinylic derivatives exhibit pronounced absorption in the visible range extending above 850 nm. Addition of other Bodipy units by coupling to a central iodophenyl entity enables filling of the gaps in absorption of the pivotal starting material. Efficient cascade energy transfer between the Bodipys is facilitated by spectral overlap between the energy donor and the energy acceptor. All photons between 350 nm and 750 nm are channeled to the distyryl centers which emit at 864 nm. Georg Thieme Verlag Stuttgart. New York.
- Sutter, Alexandra,Ziessel, Raymond
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p. 1466 - 1472
(2014/06/23)
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- Band gap control in conjugated oligomers and polymers via Lewis acids
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A method for altering the electronic and optical properties of a chemical compound having a band gap and a framework that includes π-delocalized electrons. The method includes complexing a Lewis acid to a basic site within the framework to form a Lewis ac
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Page/Page column 14-15
(2011/02/25)
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- Lewis acid adducts of narrow band gap conjugated polymers
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We report on the interaction of Lewis acids with narrow band gap conjugated copolymers containing donor and acceptor units. Examination of the widely used poly[(4,4-bis(2-ethylhexyl)cyclopenta-[2,1-b:3,4-b′]dithiophene)-2, 6-(diyl-alt-benzo[2,1,3]thiadiaz
- Welch, Gregory C.,Bazan, Guillermo C.
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supporting information; experimental part
p. 4632 - 4644
(2011/05/12)
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- Heteroheptacenes with fused thiophene and pyrrole rings
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The preparation of conjugated heteroheptacenes using an electrophilic coupling reaction induced by a super acid is reported. The new molecules containing thiophene and/or pyrrole rings are bisbenzo[b,b']thienodithieno[3,2- b:2',3'-d]pyrrole, bisbenzo[b,b']thienocyclopenta[2, l -b :3,4-b']dithiophene, and bisthieno[3,2no]thieno[2,3-f:5,4-f]carbazole. Dithieno[3,2-b:2',3'-d] pyrrole, cyclopenta[2, lb:3,4-b']dithiophene, and carbazole are used as the aromatic cores. This versatility provides access to molecules with systematically controllable physicochemical properties. Single-crystal X-ray analyses demonstrate that the type and position of the alkyl substituents significantly changes the packing properties of the new molecules. The optical and optoelectronic properties of the heteroheptacenes vary considerably depending on the number and position of the sulfur or nitrogen linkages and reveal the improved environmental stability over their hydrocarbon counterparts. The analysis of the experimental results from UV/Vis absorption/ photoluminescence (PL) spectroscopy and cyclic voltammetry were combined with DFT quantum-chemical calculations and compared with other model heteroheptacenes. The results suggest that among the acenes with the same number of fused rings, the thiophene ring fusion inside the skeleton stabilizes both HOMO and LUMO levels more effectively than pyrrole and benzene rings. The present study also shows that the new heteroheptacenes are promising candidates for the construction of electronic materials.
- Gao, Peng,Cho, Don,Yang, Xiaoyin,Enkelmann, Volker,Baumgarten, Martin,Muellen, Klaus
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supporting information; experimental part
p. 5119 - 5128
(2010/08/06)
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- Polymers with low band gaps and high charge mobility
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This disclosure relates to a polymer containing a first comonomer repeat unit and a second comonomer repeat unit different from the first comonomer repeat unit. The first comonomer repeat unit includes a cyclopentadithiophene moiety. The polymer can be used as a photoactive material in a photovoltaic cell. This disclosure also relates to such photovoltaic cells, as well as modules containing such photovoltaic cells.
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Page/Page column 8
(2010/08/11)
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