Source: China University of Science and Technology News

Professor Xiao Zhengguo's research team from the Department of Physics of the University of Science and Technology of China and the Key Laboratory of Strongly Coupled Quantum Materials Physics of the Chinese Academy of Sciences has made important progress in the preparation of large-area sky blue perovskite LED. The research team controlled the nucleation growth process by scraping the supersaturated perovskite solution, and successfully prepared a large-area, efficieny-efficient blue-sky perovskite LED, which took an important step toward the commercial application of perovskite LED lighting. The relevant results are entitled "Large-area and efficient sky-blue perovskite light-emitting diodes via blade-coating". They were published February 18 in the journal Advanced Materials.

Metal halide perovskite leds have good electrical conductivity and can achieve high luminance at low voltages, making them ideal for the next generation of energy-saving lighting. At present, the efficiency of red and green perovskite leds is very high, but the efficiency of blue light/blue light perovskite leds, which are essential in white light lighting, is relatively low, mainly because the crystallization process of blue light/blue light perovskite films is more difficult to control, resulting in poor film quality. At present, there are no reports of large-area sky blue perovskite LED.

Figure 1, Crystallization diagram (a) of a scraped supersaturated solution, and AFM diagram (b) of a perovskite film. JV and EQE curves (c), EL spectra and CIE diagrams (d) of small area PeLED device (0.04 cm2). e, PL photo of large perovskite film. f, a photograph of a large area PeLED device (28 cm2) in operation.

Xiao Zhengguo's research group adjusted the group of perovskites into CsPb(Br0.84Cl0.16)3 on the basis of the work of preparing large area and efficiency red perovskite LED by brushing (Nat.Commun.12, 147, 2021), and added additional amines halide additive to limit the growth of perovskite grains and blunt the defects. Blue light emission is realized. At the same time, DMF was used to partially replace DMSO to obtain a more volatile and supraturated perovskite precursor solution. During the scraping process, perovskite crystal nuclei would precipitate directly from the inside of the supraturated solution, which could effectively increase the density of crystal nuclei and shorten the growth process of crystal nuclei, thus preparing uniform, dense and small-grain perovskite films, as shown in FIG. 1a and b. The external quantum efficiency of the sky blue perovskite LED prepared by scraping method reached 10.3%, the EL peak was 489 nm, and the color coordinate was (0.071, 0.294). At the same time, the luminous uniformity and brightness of the large area perovskite LED (28 cm2) are very good.

Professor Xiao Zhengguo from the Department of Physics of the University of Science and Technology of China is the corresponding author of the paper, and Chu Shenglong, a doctoral student in the department of physics, is the first author of the paper. This research was supported by the National Natural Science Foundation of China, the Talent Team Project of the University of Science and Technology of China and the special Fund for Basic scientific Research operations of central universities.

Paper link:

https://onlinelibrary.wiley.com/doi/10.1002/adma.202108939

(School of Physics, Key Laboratory of Strongly Coupled Quantum Materials Physics, Chinese Academy of Sciences, Department of Scientific Research)