Improved Hole Injection into Perovskite Light-Emitting Diodes Using A Black Phosphorus Interlayer

Abstract The light‐output and efficiency of perovskite based light‐emitting diodes (PeLEDs) is limited by hole injection and high leakage current, generated by a high hole injection barrier and poor perovskite morphology, respectively. Here, a feasible strategy is reported to overcome both constraints by introducing 2D black phosphorus (BP) as hole injection layer in the PeLED stack. A continuous film composed of high‐quality, ultrathin, and large BP sheets on top of poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate simultaneously improves the hole injection and morphology of the green‐emitting inorganic CsPbBr 3 perovskite. Inclusion of the BP enhances the external quantum efficiency of CsPbBr 3 based PeLEDs from 0.7% to 2.8%.