Large‐Area and Efficient Sky‐Blue Perovskite Light‐Emitting Diodes via Blade‐Coating

Abstract Large‐area fabrication of perovskite light‐emitting diodes (PeLEDs) through mass‐production techniques has attracted growing attention due to their potential applications in lighting. Several breakthroughs are made for red/infrared and green emissions. Nevertheless, large‐area blue/sky‐blue PeLEDs, a requisite color for lighting, have not yet been reported. Here, efficient and large‐area sky‐blue PeLEDs are fabricated through blade‐coating supersaturated precursors. The volume ratio of dimethyl sulfoxide to dimethylformamide is tuned to obtain a supersaturated CsPb(Br_0.84Cl_0.16)₃ solution. Blade‐coating this supersaturated precursor results in nucleation in the solution phase with much higher nucleation sites, and a faster crystallization rate. The uniform films formed by this approach 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 are also achieved with uniform emission. This work represents a significant step forward toward flat‐panel lighting and full‐color display for the PeLEDs.