Boosting Efficiency in Polycrystalline Metal Halide Perovskite Light-Emitting Diodes

Metal halide perovskites (MHPs) have outstanding photophysical properties and are therefore being evaluated as next-generation light emitters. Within just a few years, the efficiencies of polycrystalline perovskite light-emitting diodes (PeLEDs) have been drastically improved and are catching up with those of conventional organic LEDs. The electroluminescence efficiency of polycrystalline PeLEDs has been limited by shortcomings such as limited outcoupling efficiency, charge imbalance in MHP emitting layers, difficulty controlling surface morphology, small exciton binding energy at room temperature, and nonradiative recombination at defect sites. In this Perspective, we focus on promising strategies such as optical engineering, charge balance control, morphological and nanograin engineering, and chemical modification to overcome these shortcomings and suggest future directions for research to further improve the efficiencies of polycrystalline PeLEDs.