The International Academic Exchange Event "Interface-Assisted Perovskite Phase Formation and Its Application in LEDs" Being Successfully Held

On November 3rd, Laboratory research team invited Dr. Yuan Zhongcheng from the University of Oxford to visit the Laboratory for academic exchanges.

Dr. Yuan Zhongcheng is a postdoctoral researcher and Marie Curie Fellow in the Department of Physics, University of Oxford, UK. His co-supervisor Prof. Henry Snaith is a Fellow of the Royal Society. Currently, Henry Snaith's research group has about 30 members, with main research direction on photovoltaic devices of metal halide perovskite semiconductors. In addition, Prof. Snaith is also committed to researches on perovskite light-emitting diodes (PeLEDs), synthesis of perovskite nanocrystals, development of new semiconductor materials, and fundamental measurements of optical and electronic properties of these materials. His research group has thin film preparation equipment, thin film characterization equipment, and "thin film cluster facility" that is used in vacuum deposition of advanced semiconductor materials (thermal, sputtering and atomic layer deposition), including perovskites, organic matters, metal oxidation materials, nitrides and metals.

Dr. Yuan Zhongcheng gave an academic report on "Interface-Assisted Perovskite Phase Formation and Its Application in LEDs". The report pointed out that because the phase formation process of FAPbl3 and CsPbI3 perovskites was very different, the traditional method of adjusting the ratio of cesium and formamidine to obtain cesium-formamidine lead iodide (CsPbl3-xBrx) perovskite often led to phase separation, thereby seriously affecting the quality of the film. His research group used an alkaline interface-assisted cation exchange method to successfully prepare high-quality mixed cation perovskite film CsxFA1-xPl3 and achieve arbitrary adjustment of the Cs-FA ratio in the film. In the process, the deprotonation of FA+ cations and subsequent formation of hydrogen-bonded gel effectively removed the barrier for Cs-FA ion exchange and promoted the formation of pure-phase CsxFAl-xPbl3 films.

Perovskite light-emitting devices based on such films realize continuously adjusted electroluminescence spectra in the near-infrared region, filling the luminescence gap between FAPbl3 and CsPbl3 perovskites. At the same time, the light-emitting devices all exhibit external quantum efficiencies of more than 15% and maximum radiation of more than 300Wsr-1m-2, which is the highest performance value among tunable near-infrared light-emitting devices prepared based on the solution method. In addition, his research group is also exploring methods to achieve broad-spectrum adjustment in the visible light region, providing new ideas and methods for adjusting the perovskite luminescence spectrum and improving device operating stability.

At the exchange meeting, participants had a full discussion with Dr. Yuan Zhongcheng on issues such as "how to examine the life of LEDs" and "whether zinc oxide (ZnO) films are usually used as transmission layer substrates for light-emitting devices", etc. The atmosphere of the exchange was very lively.

After the exchange, they also discussed follow-up arrangements and further exchange and cooperation plans. Through this academic exchange, the Laboratory's research team experienced the high-quality teaching level, high-quality teaching resources, advanced teaching concepts, and multi-cultural exchange and integration of a world-renowned university. The Laboratory will take this opportunity to further cooperate with Prof. Henry Snaith and his research group. It is hoped that the two sides can expand cooperation areas, establish a stable cooperation and exchange mechanism, and explore long-term exchange and cooperation projects, thereby providing more learning and exchange opportunities for the Laboratory's scientific research teams and advancing researches on major scientific research tasks.