Xia Yu, Song Bin, Zhang Zhipeng, Wang Kai-Li, Li Yu-Han, Li Nan, Chen Chun-Hao, Chen Jing, Xing Guichuan, Wang Zhao-Kui
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, 215123, China.
Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, 999078 Macao SAR, China.
Angew Chem Int Ed Engl. 2024 May 27;63(22):e202403739. doi: 10.1002/anie.202403739. Epub 2024 Apr 23.
Deep-blue perovskite light-emitting diodes (PeLEDs) based on quasi-two-dimensional (quasi-2D) systems exist heightened sensitivity to the domain distribution. The top-down crystallization mode will lead to a vertical gradient distribution of quantum well (QW) structure, which is unfavorable for deep-blue emission. Herein, a thermal gradient annealing treatment is proposed to address the polydispersity issue of vertical QWs in quasi-2D perovskites. The formation of large-n domains at the upper interface of the perovskite film can be effectively inhibited by introducing a low-temperature source in the annealing process. Combined with the utilization of NaBr to inhibit the undesirable n=1 domain, a vertically concentrated QW structure is ultimately attained. As a result, the fabricated device delivers a narrow and stable deep-blue emission at 458 nm with an impressive external quantum efficiency (EQE) of 5.82 %. Green and sky-blue PeLEDs with remarkable EQE of 21.83 % and 17.51 % are also successfully achieved, respectively, by using the same strategy. The findings provide a universal strategy across the entire quasi-2D perovskites, paving the way for future practical application of PeLEDs.
基于准二维（quasi-2D）体系的深蓝色钙钛矿发光二极管（PeLEDs）对畴分布存在更高的敏感性。自上而下的结晶模式会导致量子阱（QW）结构的垂直梯度分布，这不利于深蓝色发光。在此，提出一种热梯度退火处理方法来解决准二维钙钛矿中垂直量子阱的多分散性问题。通过在退火过程中引入低温源，可以有效抑制钙钛矿薄膜上界面处大n值畴的形成。结合使用溴化钠抑制不期望的n=1畴，最终获得了垂直集中的量子阱结构。结果，所制备的器件在458nm处发出窄且稳定的深蓝色光，具有5.82%的令人印象深刻的外量子效率（EQE）。通过使用相同的策略，还分别成功制备出了外量子效率分别为21.83%和17.51%的绿色和天蓝色PeLEDs。这些发现为整个准二维钙钛矿提供了一种通用策略，为PeLEDs的未来实际应用铺平了道路。
