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.

The peak external quantum efficiency of the blade-coated PeLEDs reaches 10.3% with sky-blue emission (489 nm).

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.”



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