The research group led by Prof. XIAO Zhengguo from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences prepared large-area and efficient sky-blue perovskite light-emitting diodes (PeLEDs) by blade-coating supersaturated perovskite solution. This work was published in Advanced Materials .
Metal halide PeLEDs can achieve high luminance at low voltage due to their high electrical conductivity, making them ideal for the next generation of energy-saving lighting. The external quantum efficiency (EQE) of red/infrared and green PeLEDs is high at present. Blue/sky-blue PeLEDs are essential for white lighting, while the EQE of blue light is relatively low. This is because the crystallization process of blue/sky-blue perovskite film is difficult to control, which results in poor film quality. Till now, there are no reports on the formation of large-area blue/sky-blue PeLEDs.
Researchers in this work adjusted the composition of perovskite into CsPb(Br 0.84 Cl 0.16 ) 3 based on their previous robust perovskite blade-coating technique for red PeLEDs. They added additional halide amine additives to limit the growth of perovskite grains and passivate the traps, to achieve the sky-blue emission.
Meanwhile, they partially replaced dimethyl sulfoxide (DMSO) with dimethylformamide (DMF) to obtain a more volatile and supersaturated perovskite precursor solution. Perovskite crystal nucleus will precipitate directly from inside of the supersaturated solution in the process of blade-coating, which can effectively increase the density of the nucleus and accelerate the process of nucleation, crystallization, and film-forming, to prepare uniform perovskite films with small grains.
The EQE for blue/sky-blue PeLEDs, prepared by the blade-coating method, reached 10.3%, and the luminescence uniformity and brightness in an area of 28cm 2 of the PeLEDs are both very good.
This work represents an important step to the commercial application of PeLED lighting.
Advanced Materials
Large-Area and Efficient Sky-Blue Perovskite Light-Emitting Diodes Via Blade-Coating
18-Feb-2022