University of Science and Technology of China successfully prepares high-performance pure red perovskite LED

On May 8, according to the University of Science and Technology of China, its team of Yao Hongbin, Fan Fengjia, Lin Yue, and Hu Wei found the cause of the performance bottleneck of pure red perovskite LEDs and successfully prepared high-performance pure red perovskite LEDs. Relevant research results were published online in the international academic journal Nature on May 7, Beijing time.

Schematic diagram of perovskite three-dimensional heterojunction suppressing hole leakage in LEDs (Image source: Nature)

According to reports, metal halide perovskite is a new generation of star semiconductor materials. As a light-emitting layer material in LEDs, it has the advantages of high carrier mobility, high color purity, and wide color gamut. As a light source of one of the three primary colors, pure red perovskite LED has great potential in the future high-definition display field and has bright application prospects. However, there are currently research difficulties such as difficulty in balancing brightness and efficiency. The research team from the University of Science and Technology of China mainly solved the problem of sudden drop in efficiency when the brightness of pure red perovskite LEDs increases.

Electrically excited transient absorption spectroscopy (EETA), a new method independently developed by Fan Fengjia’s team to “take pictures” of LEDs, detects electrons (negative charge) and holes (positive charge) inside the LED and found that hole leakage into the electron transport layer is the cause of the performance bottleneck of pure red perovskite LEDs.

Yao Hongbin's team proposed a new material structure design "three-dimensional perovskite heterojunction" to effectively suppress hole leakage. The team inserted organic molecules inside the perovskite lattice, changed the crystal structure of the luminescent layer, and built a "dam" that prevents holes from leaving the luminescent layer - a "wide bandgap energy barrier". While limiting the area, it maintains high mobility. Professor Yao Hongbin and Professor Hu Wei conducted a theoretical structural analysis of this innovative design, while Professor Lin Yue fully verified the material using a spherical aberration electron microscope.

Design and material characterization of three-dimensional CsPbI3-xBrx perovskite heterojunction (Image source: Nature)

The pure red perovskite LED created by the University of Science and Technology of China team based on the "three-dimensional perovskite heterojunction" has internationally leading high performance in terms of peak external quantum efficiency, maximum brightness, efficiency roll-off, etc., demonstrating the huge potential of the three-dimensional perovskite heterojunction material created by the team in the development of efficient, bright and stable perovskite LEDs.

Song Yonghui (Ph.D.), Li Bo (Postdoctoral), Wang Zijian (Ph.D. candidate) and Tai Xiaolin (Ph.D. candidate) of the University of Science and Technology of China are the co-first authors of this article; Professor Yao Hongbin, Professor Fan Fengjia, Professor Lin Yue and Professor Hu Wei of the University of Science and Technology of China are the co-corresponding authors of this paper. This work was supported by the National Natural Science Foundation of China and the Ministry of Science and Technology. The Physical and Chemical Science Experiment Center provided support for characterization equipment such as SEM, PL, UV-vis, and spherical aberration electron microscopy for the development of this project.