Guo Zhenyu, Zhang Yu, Wang Bingzhe, Wang Liding, Zhou Ning, Qiu Zhiwen, Li Nengxu, Chen Yihua, Zhu Cheng, Xie Haipeng, Song Tinglu, Song Lei, Xue Haibo, Tao Shuxia, Chen Qi, Xing Guichuan, Xiao Lixin, Liu Zhiwei, Zhou Huanping
Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Beijing Key Laboratory for Theory and Technology of Advanced Battery Materials, School of Materials Science and Engineering, Peking University, Beijing, 100871, China.
Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Macau, 999078, China.
Adv Mater. 2021 Oct;33(40):e2102246. doi: 10.1002/adma.202102246. Epub 2021 Aug 15.
Quasi-2D (Q-2D) perovskites are promising materials applied in light-emitting diodes (LEDs) due to their high exciton binding energy and quantum confinement effects. However, Q-2D perovskites feature a multiphase structure with abundant grain boundaries and interfaces, leading to nonradiative loss during the energy-transfer process. Here, a more efficient energy transfer in Q-2D perovskites is achieved by manipulating the crystallization kinetics of different-n phases. A series of alkali-metal bromides is utilized to manipulate the nucleation and growth of Q-2D perovskites, which is likely associated with the Coulomb interaction between alkali-metal ions and the negatively charged PbBr frames. The incorporation of K is found to restrict the nucleation of high-n phases and allows the subsequent growth of low-n phases, contributing to a spatially more homogeneous distribution of different-n phases and promoted energy transfer. As a result, highly efficient green Q-2D perovskites LEDs with a champion EQE of 18.15% and a maximum brightness of 25 800 cd m are achieved. The findings affirm a novel method to optimize the performance of Q-2D perovskite LEDs.
准二维（Q-2D）钙钛矿因其高激子束缚能和量子限制效应，是应用于发光二极管（LED）的很有前景的材料。然而，Q-2D钙钛矿具有多相结构，存在大量晶界和界面，导致能量转移过程中的非辐射损失。在此，通过控制不同n相的结晶动力学，在Q-2D钙钛矿中实现了更高效的能量转移。一系列碱金属溴化物被用于控制Q-2D钙钛矿的成核和生长，这可能与碱金属离子和带负电的PbBr 框架之间的库仑相互作用有关。发现掺入K可限制高n相的成核，并允许随后低n相的生长，有助于不同n相在空间上更均匀的分布并促进能量转移。结果，实现了高效绿色Q-2D钙钛矿LED，其最佳外量子效率（EQE）为18.15%，最大亮度为25800 cd m 。这些发现证实了一种优化Q-2D钙钛矿LED性能的新方法。
