Surface mediated ligands addressing bottleneck of room-temperature synthesized inorganic perovskite nanocrystals toward efficient light-emitting diodes

• Published in: Nano energy 2020-04, Vol.70, p.104467, Article 104467
• Main Authors: Dai, Jinfei, Xi, Jun, Zu, Yanqing, Li, Lu, Xu, Jie, Shi, Yifei, Liu, Xiaoyun, Fan, Qinhua, Zhang, Junjie, Wang, ShuangPeng, Yuan, Fang, Dong, Hua, Jiao, Bo, Hou, Xun, Wu, Zhaoxin
• Format: Article
• Language: English
• Subjects: CsPbBr3; Defect passivation; Double-terminal ligand; Light-emitting diodes; Nanocrystals
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2020.104467

Cesium lead halide perovskites (CsPbX3) have become superior candidates for perspective optoelectronic applications. However, room temperature synthesized CsPbX3 nanocrystals (NCs) suffer from serious lattice/surface traps, mostly induced by nonequilibrium reactions and polar solvent systems. Thus, direct assembly of such poor crystals cannot be available toward high efficiency light emitting diodes (LEDs). To address this issue, differing from the general post-treatment works, here we propose a double-terminal diamine bromide salt to in situ passivate the surface traps of room temperature synthesized CsPbBr3 NCs. High-quality NC solutions with photoluminescence quantum yield (PLQY) beyond 90% are obtained owing to the renovated surface bromide vacancies. Meanwhile, instead of longer oleylamine (OLA) ligand, the abridged diamine bromine ligand could significantly enhance charge transport throughout the NC film. In addition, the NC based LED performance is found related to chain length of the ligand, where the optimal luminance of 14021 Cd m−2 and current efficiency of 25.5 Cd A−1 are achieved by 1, 4-butanediamine bromide passivated NC devices. This work provides a direct efficient approach to meet the device application of room temperature synthesized perovskite NCs, underlines the significance of selective ligands to address the challenges of NC emitters in future displays and solid-state lighting. [Display omitted] •High PLQY (>90%) CsPbBr3 nanocrystals was synthesized by an in situ double-terminal diamine passivation protocol.•The charge path between adjacent nanocrystals is reformed, from an inefficient longer path to the efficient shorter one.•Significantly around 28 fold increase of light-emitting device current efficiency (CE) compared with controlsample.•A competitive efficiency of LED device (25.5 cd/A) was achieved with further ligand chain length optimizing.