Green perovskite light-emitting diodes with simultaneous high luminance and quantum efficiency through charge injection engineering

Abstract

Metal halide perovskite light emitting diodes (PeLEDs) have recently experienced rapid development due to the tunable emission wavelengths, narrow emission linewidth and low material cost. To achieve state-of-the-art performance, the high photoluminescence quantum yield (PLQY) of the active emission layer, the balanced charge injection, and the optimized optical extraction should be considered simultaneously. Multiple chemical passivation strategies have been provided as controllable and efficient methods to improve the PLQY of the perovskite layer. However, high luminance under large injection current and high external quantum efficiency (EQE) can hardly be achieved due to Auger recombination at high carrier density. Here, we decreased the electron injection barrier by tuning the Fermi-level of the perovskite, leading to a reduced turn on voltage. Through molecular doping of the hole injection material, a more balanced hole injection was achieved. At last, a device with modified charge injection realizes high luminance and quantum efficiency simultaneously. The best device exhibits luminance of 55,000 cd m−2, EQE of 8.02% at the working voltage of 2.65 V, current density of 115 mA cm−2, and shows EQE T50 stability around 160 min at 100 mA cm−2 injection current density.