Recently, Professor Xiao Zhengguo’s research team from the School of Physics of the University of Science and Technology of China, the Key Laboratory of Strongly Coupled Quantum Material Physics of the Chinese Academy of Sciences and the Hefei National Research Center for Microscale Material Science has made important progress in the field of preparing efficient and stable perovskite single crystal LEDs.

The research team has grown high-quality, large-area and ultra-thin perovskite single crystals by using the space restriction method, and prepared perovskite single crystal LED with brightness of more than 86000 cd/m2 and life of up to 12500 h for the first time, which has taken an important step towards the application of perovskite LED to human lighting. The relevant achievements, entitled “High bright and stable single-crystal perovskite light-emitting diodes”, were published in Nature Photonics on February 27.

Metal halide perovskite has become a new generation of LED display and lighting materials due to its tunable wavelength, narrow half-peak width and low-temperature preparation. At present, the external quantum efficiency (EQE) of perovskite LED (PeLED) based on polycrystalline thin film has exceeded 20%, comparable to commercial organic LED (OLED). In recent years, the service life of most of the reported high-efficiency perovskite LED devices ranges from hundreds to thousands of hours, still lagging behind OLEDs. The stability of the device will be affected by such factors as ion movement, unbalanced carrier implantation and joule heat generated during operation. In addition, the serious Auger recombination in polycrystalline perovskite devices also limits the brightness of the devices.

In response to the above problems, Xiao Zhengguo’s research team used the space restriction method to grow perovskite single crystals on the substrate in situ. By adjusting the growth conditions, introducing organic amines and polymers, the crystal quality was effectively improved, thus preparing high-quality MA0.8FA0.2PbBr3 thin single crystals with a minimum thickness of 1.5 μ m. 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 thin single crystal as the light emitting layer has an EQE of 11.2%, a brightness of more than 86000 cd/m2, and a lifetime of 12500 h. It has initially reached the threshold of commercialization, and has become one of the most stable perovskite LED devices at present.

The above work fully demonstrates that using thin perovskite single crystal as the light emitting layer is a feasible solution to the stability problem, and that perovskite single crystal LED has a great prospect in the field of human lighting and display.