Researchers from Beihang University and the University of Science and Technology of China (USTC) of the Chinese Academy of Science have developed efficient and large-area sky-blue Perovskite-based LEDs, through blade-coating supersaturated precursors.
This approach results in nucleation in the solution phase with much higher nucleation sites, and a faster crystallization rate. The uniform films formed by this method reportedly exhibit smaller grain size, lower trap density, and higher radiative recombination rate.
Benefitting from the robustness of this blade-coating technique, large-area sky-blue PeLEDs with a device area of 28 cm2 were also achieved with uniform emission. This work could represent a step forward toward flat-panel lighting and full-color display for the PeLEDs.
The precursor, a CsPb(Br0.84Cl0.16)3 solution using a custom solvent blend, was blade-coated onto a substrate where the substance crystallized into grains ' halide amine additives controlled the growth of perovskite grains and passivate the traps.
'They partially replaced dimethyl sulfoxide with dimethylformamide to obtain a more volatile and supersaturated perovskite precursor solution,' according to the team. '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.'