Wang Shixun, Shen Xinyu, Zhang Yu, Zhuang Xingwei, Xue Dingke, Zhang Xiangtong, Wu Jinlei, Zhu Jinyang, Shi Zhifeng, Kershaw Stephen V, Yu William W, Rogach Andrey L
State Key Laboratory of Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University, Changchun, 130012, China.
Department of Materials Science and Engineering, and Centre for Functional Photonics (CFP), City University of Hong Kong, Kowloon, Hong Kong S.A.R., China.
Small. 2019 Aug;15(34):e1901828. doi: 10.1002/smll.201901828. Epub 2019 Jul 5.
All-inorganic cesium lead halide perovskite nanocrystals (NCs) have demonstrated excellent optical properties and an encouraging potential for optoelectronic applications; however, mixed-halide perovskites, especially CsPb(Cl/Br) NCs, still show lower photoluminescence quantum yields (PL QY) than the corresponding single-halide materials. Herein, anhydrous oxalic acid is used to post-treat CsPb(Cl/Br) NCs in order to initially remove surface defects and halide vacancies, and thus, to improve their PL QY from 11% to 89% for the emission of 451 nm. Furthermore, due to the continuous chelating reaction with the oxalate ion, chloride anions from the mixed-halide CsPb(Cl/Br) perovskite NCs could be extracted, and green emitting CsPbBr NCs with PL QY of 85% at 511 nm emission are obtained. Besides being useful to improve the emission of CsPb(Cl/Br) NCs, the oxalic acid treatment strategy introduced here provides a further tool to adjust the distribution of halide anions in mixed-halide perovskites without using any halide additives.
全无机铯铅卤化物钙钛矿纳米晶体（NCs）已展现出优异的光学性能以及在光电子应用方面令人鼓舞的潜力；然而，混合卤化物钙钛矿，尤其是CsPb(Cl/Br) NCs，其光致发光量子产率（PL QY）仍低于相应的单卤化物材料。在此，使用无水草酸对CsPb(Cl/Br) NCs进行后处理，以初步去除表面缺陷和卤化物空位，从而将其在451 nm发射波长下的PL QY从11%提高到89%。此外，由于与草酸根离子的持续螯合反应，混合卤化物CsPb(Cl/Br)钙钛矿NCs中的氯离子可被萃取出来，从而获得在511 nm发射波长下PL QY为85%的绿色发光CsPbBr NCs。除了有助于改善CsPb(Cl/Br) NCs的发光性能外，此处引入的草酸处理策略还提供了一种无需使用任何卤化物添加剂就能调节混合卤化物钙钛矿中卤化物阴离子分布的进一步工具。
