China University of Science and Technology has made important progress in the field of large-area sky blue perovskite LEDs

A research group led by Professor Xiao Zhengguo from the Department of Physics at the University of Science and Technology of China and the Key Laboratory of Strongly Coupled Quantum Materials Physics at the Chinese Academy of Sciences has made significant progress in the development of large-area sky-blue perovskite LEDs. The group controlled the nucleation growth process by scraping a supersaturated perovskite solution and successfully prepared a large-area, high-efficiency sky-blue perovskite LED. This achievement is a crucial step towards the commercial application of perovskite LED lighting. The corresponding study, titled "Large-area and efficient sky-blue perovskite light-emitting diodes via blade-coating," was published in the journal Advanced Materials on February 18th.

Metal halide perovskite LEDs have good electrical conductivity and can achieve high luminous brightness at lower voltages, making them ideal candidates for next-generation energy-saving lighting. Currently, both red and green perovskite LEDs have high efficiencies, but the sky-blue/blue-light perovskite LEDs, which are essential for white light illumination, have low efficiency, mainly because of sky-blue/blue-light perovskite films. The crystallization process is more difficult to control, resulting in poor film quality. At present, there are no reports on large-area sky-blue perovskite LEDs.

Xiao Zhengguo's research group adjusted the composition of perovskite to CsPb (Br0.84Cl0.16) based on the work of preparing large-area, high-efficiency red perovskite LEDs by blade coating (Nat. Commun.12, 147, 2021). 3, and adding additional halide amine additives to limit the growth of perovskite grains and passivate defects to achieve sky blue light emission. At the same time, DMF was used to partially replace DMSO to obtain a more volatile and supersaturated perovskite precursor solution. During the blade coating process, the perovskite crystal nucleus would be directly precipitated from the interior of the supersaturated solution, which can effectively increase the crystal nucleus. density and shorten the process of nucleation growth, resulting in the preparation of uniform dense, small-grained perovskite films, as shown in Fig. 1a,b. The external quantum efficiency of the sky blue perovskite LED prepared by the blade coating method reaches 10.3%, the EL peak position is 489 nm, and the color coordinates are (0.071, 0.294). Meanwhile, the large-area perovskite LED (28 cm2) exhibits good luminous uniformity and brightness.

Professor Xiao Zhengguo of the Department of Physics, University of Science and Technology of China is the corresponding author of the paper, and Chu Shenglong, a doctoral student of the Department of Physics, is the first author of the paper. This research was funded by the National Natural Science Foundation of China, the Talent Team Project of the University of Science and Technology of China, and the special funds for the basic scientific research business expenses of central universities.