Recently, the research group of Professor Xiao Zhengguo from the School of Physics of the University of Science and Technology of China, the Key Laboratory of Strongly Coupled Quantum Materials Physics of the Chinese Academy of Sciences, and the Hefei National Research Center for Microscale Physical Sciences has made important progress in the field of preparing efficient and stable perovskite single crystal LEDs.
The research team used the spatial confinement method to grow high-quality, large-area, ultra-thin perovskite single crystals, and for the first time prepared a perovskite single-crystal LED with a brightness of over 86,000 cd/m2 and a life of up to 12,500 h. The application of mineral LED in human lighting has taken an important step. The relevant results, titled "Highly bright and stable single-crystal perovskite light-emitting diodes", were published in the magazine "Nature Photonics" on February 27.
Metal halide perovskites have become a new generation of LED display and lighting materials due to their adjustable luminescence wavelength, narrow luminescence half-peak width, and low-temperature preparation. Currently, the external quantum efficiency (EQE) of perovskite LEDs (PeLEDs) based on polycrystalline films has exceeded 20%, which is comparable to commercial organic LEDs (OLEDs). In recent years, the lifetimes of the vast majority of high-efficiency perovskite LED devices reported range from hundreds to thousands of hours, still lagging behind OLEDs. Factors such as ion movement, unbalanced carrier injection, and Joule heat generated during operation will affect device stability. In addition, severe Auger recombination in polycrystalline perovskite devices also limits the brightness of the devices.
In response to the above problems, Xiao Zhengguo's research group used the spatial confinement method to grow perovskite single crystals in situ on the substrate. By regulating the growth conditions and introducing organic amines and polymers, the crystal quality was effectively improved, thereby preparing high-quality MA0. 8FA0.2PbBr3 thin single crystal, the minimum thickness is only 1.5 μm, the surface roughness is less than 0.6 nm, and the internal fluorescence quantum yield (PLQYint) reaches 90%. The perovskite single crystal LED device prepared with a thin single crystal as the light-emitting layer has an EQE of 11.2%, a brightness of over 86,000 cd/m2, and a lifespan of up to 12,500 h. It has initially reached the commercialization threshold and has become the most stable perovskite currently. One of the LED devices.
The above work fully demonstrates that using perovskite thin single crystals as the light-emitting layer is a feasible solution to the stability problem, as well as the great prospects of perovskite single crystal LEDs in the field of human lighting and display.
Illustration: Schematic diagram of single crystal growth by spatial confinement method (a), microscope image of single crystal (b), device structure of perovskite single crystal LED (c), performance characterization of perovskite single crystal LED (d-f).
Professor Xiao Zhengguo, School of Physics, University of Science and Technology of China, is the corresponding author of the paper. Chen Wenjing, a postdoctoral fellow in the Department of Physics, and master students Huang Zongming and Yao Haitao are the co-first authors of the paper. This research was funded by the National Natural Science Foundation of China, the Organization Department of the Central Committee of the Communist Party of China and the University of Science and Technology of China.
Source: China University of Science and Technology News Network