Chen Ting, Xu Yanqiao, Xie Zhixiang, Jiang Weihui, Wang Lianjun, Jiang Wan
School of Material Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333001, China.
Nanoscale. 2020 May 7;12(17):9569-9580. doi: 10.1039/d0nr00579g. Epub 2020 Apr 21.
CsPbX (X = Cl, Br, I) nanocrystals (NCs) are competitive fluorescent materials for lighting and displays owing to their excellent photophysical properties. However, the stability and optoelectronic performance of the perovskite NCs are severely limited by the highly dynamic binding feature of the present ligand strategy. Herein, a facile approach was employed to synthesize CsPbBr NCs with the assistance of the ionic liquid (IL) 1-butyl-3-methylimidazolium bromide ([Bmim]Br). By strictly controlling the addition dose of [Bmim]Br (n/n = 0.125) into the reaction precursor, it is possible to obtain the desired cube-shaped and monodisperse CsPbBr NCs with simultaneous enhancement of the storage and irradiation stability as well as photoluminescence quantum yields (PLQYs, ∼91%). Stability tests show that the emission intensity of the parent CsPbBr NCs drops to 50% of its initial emission intensity after storage under an open atmosphere for 91 days, while the sample prepared with the assistance of [Bmim]Br can maintain 82% of the PL intensity. Meanwhile, the modified CsPbBr NCs also present superior photo-stability, and still maintain 81% of the original PL intensity after continuous illumination under an ultraviolet lamp for 24 h, but the intensity of the parent CsPbBr NCs reduces to 35% of the original intensity. Through the morphology, composition, and luminescence kinetics evolution of CsPbBr NCs, these benefits were attributed to the modulation by [Bmim]Br, which could effectively provide Br ions for the formation and growth of NCs, resulting in the reduction of surface traps. Moreover, [Bmim]Br exhibited strong interactions with NCs, and the deprotonation of oleic acid (OA) was inhibited, resulting in the effective passivation of surface defects. Finally, CsPbX NCs with different compositions were obtained via a facile anion exchange reaction, leading to the tunable emission in the range of 462-665 nm and a wide colour gamut (129.65% NTSC standard). This work opens a new avenue for modulating the surface properties of CsPbX NCs, which will create opportunities for their application in the photoelectric field.
CsPbX（X = Cl、Br、I）纳米晶体（NCs）因其优异的光物理性质而成为用于照明和显示的有竞争力的荧光材料。然而，钙钛矿NCs的稳定性和光电性能受到当前配体策略高度动态结合特性的严重限制。在此，采用一种简便的方法在离子液体（IL）1-丁基-3-甲基咪唑溴盐（[Bmim]Br）的辅助下合成CsPbBr NCs。通过严格控制[Bmim]Br加入反应前驱体中的剂量（n/n = 0.125），有可能获得所需的立方体形且单分散的CsPbBr NCs，同时提高存储和辐照稳定性以及光致发光量子产率（PLQYs，~91%）。稳定性测试表明，母体CsPbBr NCs在开放大气中储存91天后，其发射强度降至初始发射强度的50%，而在[Bmim]Br辅助下制备的样品可保持82%的PL强度。同时，改性后的CsPbBr NCs还表现出优异的光稳定性，在紫外灯下连续照射24小时后仍保持81%的原始PL强度，但母体CsPbBr NCs的强度降至原始强度的35%。通过CsPbBr NCs的形貌、组成和发光动力学演变，这些益处归因于[Bmim]Br的调制作用，它可以有效地为NCs的形成和生长提供Br离子，从而减少表面陷阱。此外，[Bmim]Br与NCs表现出强相互作用，抑制了油酸（OA）的去质子化，从而有效钝化表面缺陷。最后，通过简便的阴离子交换反应获得了不同组成的CsPbX NCs，实现了462 - 665 nm范围内的可调发射以及宽色域（129.65% NTSC标准）。这项工作为调节CsPbX NCs的表面性质开辟了一条新途径，并将为其在光电领域的应用创造机会。
