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

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(Br0.84 Cl0.16 )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.