Tong Yunfang, Bi Xiaoying, Xu Shuang, Min Hao, Cheng Lu, Kuang Zhiyuan, Yuan Lingzhi, Zhou Fuyi, Chu Ying, Xu Lei, Zhu Lin, Zhao Ni, Wang Nana, Huang Wei, Wang Jianpu
Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM) & School of Flexible Electronics (Future Technologies), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing, 211816, China.
Strait Laboratory of Flexible Electronics (SLoFE), Fuzhou, Fujian, 350117, China.
Adv Mater. 2023 Jan;35(3):e2207111. doi: 10.1002/adma.202207111. Epub 2022 Dec 12.
3D perovskites are promising to achieve efficient and bright deep-blue light-emitting diodes (LEDs), which are required for lighting and display applications. However, the efficiency of deep-blue 3D perovskite-based LEDs is limited by high density of defects in perovskites, and their deep-blue emission is not easy to achieve due to the halide phase separation and low solubility of chloride in precursor solutions. Here, an in situ halide exchange method is developed to achieve deep-blue 3D perovskites by spin-coating an organic halide salts solution to treat blue 3D perovskites. It is revealed that the halide-exchange process is mainly determined by halide ion diffusion targeting a concentration equalization, which leads to homogeneous 3D mixed-halide perovskites. By further introducing multifunctional organic ammonium halide salts into the exchange solution to passivate defects, high-quality deep-blue perovskites with reduced trap density can be obtained. This approach leads to efficient deep-blue perovskite LEDs with a peak external quantum efficiency (EQE) of 4.6% and a luminance of 1680 cd m , which show color coordinates of (0.131, 0.055), very close to the Rec. 2020 blue standard. Moreover, the halide exchange method is bidirectional, and blue perovskite LEDs can be achieved with color coordinates of (0.095, 0.160), exhibiting a high EQE of 11.3%.
三维钙钛矿有望实现高效且明亮的深蓝色发光二极管（LED），这是照明和显示应用所必需的。然而，基于三维钙钛矿的深蓝色LED的效率受到钙钛矿中高密度缺陷的限制，并且由于卤化物相分离以及氯化物在前体溶液中的低溶解度，其深蓝色发射并不容易实现。在此，开发了一种原位卤化物交换方法，通过旋涂有机卤化物盐溶液来处理蓝色三维钙钛矿，以实现深蓝色三维钙钛矿。结果表明，卤化物交换过程主要由卤离子扩散决定，目标是浓度均衡，这导致了均匀的三维混合卤化物钙钛矿。通过进一步将多功能有机卤化铵盐引入交换溶液中以钝化缺陷，可以获得具有降低陷阱密度的高质量深蓝色钙钛矿。这种方法导致了高效的深蓝色钙钛矿LED，其峰值外量子效率（EQE）为4.6%，亮度为1680 cd m，色坐标为（0.131, 0.055），非常接近Rec. 2020蓝色标准。此外，卤化物交换方法是双向的，可以实现色坐标为（0.095, 0.160）的蓝色钙钛矿LED，其具有11.3%的高EQE。
