- Potassium Bromide Surface Passivation on CsPbI3-xBrx Nanocrystals for Efficient and Stable Pure Red Perovskite Light-Emitting Diodes
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All-inorganic lead halide perovskite nanocrystals (NCs) are potential candidates for fabricating high-performance light-emitting diodes (LEDs) owing to their precisely tunable bandgaps, high photoluminescence (PL) efficiency, and excellent color purities. However, the performance of pure red (630-640 nm) all-inorganic perovskite LEDs is still limited by the halide segregation-induced instability of the electroluminescence (EL) of mixed halide CsPbI3-xBrx NCs. Herein, we report an effective approach to improving the EL stability of pure red all-inorganic CsPbI3-xBrx NC-based LEDs via the passivation of potassium bromide on NCs. By adding potassium oleate to the reaction system, we obtained potassium bromide surface-passivated (KBr-passivated) CsPbI3-xBrx NCs with pure red PL emission and a photoluminescence quantum yield (PLQY) exceeding 90%. We determine that most potassium ions present on the surface of NCs bind with bromide ions and thus demonstrate that potassium bromide surface passivation of NCs can both improve the PL stability and inhibit the halide segregation of NCs. Using KBr-passivated CsPbI3-xBrx NCs as an emitting layer, we fabricated stable and pure red perovskite LEDs with emission at 637 nm, showing a maximum brightness of 2671 cd m-2, maximum external quantum efficiency of 3.55%, and good EL stability. The proposed KBr-passivated NC strategy will open a new avenue for fabricating efficient, stable, and tunable pure color perovskite NC LEDs.
- Yang, Jun-Nan,Song, Yang,Yao, Ji-Song,Wang, Kun-Hua,Wang, Jing-Jing,Zhu, Bai-Sheng,Yao, Ming-Ming,Rahman, Sami Ur,Lan, Yi-Feng,Fan, Feng-Jia,Yao, Hong-Bin
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p. 2956 - 2967
(2020/02/04)
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- Continuous preparation method of metal fatty acid salt
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The invention relates to a continuous preparation method of metal fatty acid salt. The continuous preparation method of the metal fatty acid salt comprises the step of continuously enabling fatty acidand metal hydroxides to react in a solvent and prepare the metal fatty acid salt in a microchannel reactor or pipeline reactor. The preparation method disclosed by the invention can control the particle diameter of a product material to be within 70nm and 1000nm, and the particle diameter of the product material can be adjusted as needed; the metal fatty acid salt is simple in preparation method,short in technological process, few in three wastes (waste water, waste residues and waste gas), beneficial to environmental protection and suitable for industrial production; the reactor used in theinvention has short reaction time, high safety, high efficiency and large productivity, and can realize continuous production, furthermore, the space utilization rate of workshops is high, and mass production can be realized; by adopting the preparation method disclosed by the invention, the solvent can be recycled to lower the production cost; and the preparation method has high conversion rateof raw materials, stable quality and high purity.
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Paragraph 0096; 0097; 0098; 0099
(2019/04/04)
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- Comprehensive studies of the Li+ effect on NaYF4:Yb/Er nanocrystals: Morphology, structure, and upconversion luminescence
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Impurity doping plays a critical role in altering the properties of target nanomaterials in terms of designed morphologies, crystal structures, and functionalities. In this work, we have performed a comprehensive investigation of the effect of Li+ doping on the morphology, crystal structure, and upconversion luminescence of NaYF4:Yb/Er nanocrystals. Different Li+ sources, e.g., LiOA and LiOH, were used and the Li+ doping concentration varied from 0 to 100 mol%. The final product changes from hexagonal NaYF4:Yb/Er to the mixture of cubic NaYF4:Yb/Er and tetragonal LiYF4:Yb/Er, and finally to pure tetragonal LiYF4:Yb/Er. More importantly, at an ultra-low concentration of 0.5 mol% Li+ doping, as high as 34 times green and 101 times red emission enhancements are achieved.
- Xie, Xiaoji,Wang, Xiuwen,Zhang, Xi,Wang, Yangbo,Li, Hongyu,Xie, Juan,Wei, Tian,Huang, Qianwen,Huang, Ling,Huang, Wei
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supporting information
p. 8968 - 8974
(2017/07/24)
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