Hole-Injection Layer-Free Perovskite Light-Emitting Diodes.

In this study, a dual-source vapor evaporation method was employed to fabricate the high-quality CsPbBr thin films with a good crystalline and high surface coverage. Temperature-dependent and excitation power-dependent photoluminescence measurements were performed to study the optical properties of the CsPbBr material. Further, based on the experimental data, the temperature sensitivity coefficient of band gap and exciton binding energy were estimated. More importantly, for the first time, we designed and prepared a hole-injection layer-free perovskite light-emitting diode (LED) based on the Au/MgO/CsPbBr/n-MgZnO/n-GaN structure, producing an intense green emission (∼538 nm) with a high purity. Besides, the device demonstrated a high luminance of 5025 cd/m, an external quantum efficiency of 1.46%, a current efficiency of 1.92 cd/A, and a power efficiency of 1.76 lm/W. We studied in detail the current-voltage and electroluminescence properties of the prepared device and proposed the hole generation models and the carrier transport/recombination mechanisms to make these interesting characteristics certain. The results obtained would provide a new and effective strategy for the design and preparation of perovskite LEDs.