Vacuum-Deposited Perovskite LED by Interface Defect Passivation With Better Color Stability

Preparation of all-inorganic perovskite light-emitting diodes (PeLEDs) based on the thermal evaporation has sparked research interest in recent years. However, there are few reports about the blue-emitting PeLEDs by thermal evaporation, and the performance of blue-emitting PeLEDs made by thermal evaporation is much lower than that by solution process. Here, we construct blue-emitting PeLED based on thermally evaporated CsPbBrxCl $_{\mathrm {3-x}}$ and adopted interface engineering to improve device performance and suppress redshift phenomenon. It is found that ammonium bromide could not only passivate the interface defect but also provide extra Br atoms, changing the Br/Cl ratio and resulting the narrowed energy bandgap. The best device exhibited an electroluminescent (EL) peak at 483 nm with a maximum brightness of 1121 cd/m2, a maximum current efficiency of 0.6 cd/A and a peak EQE of 0.52%. Our work would provide beneficial suggestion to improve the mixed halide blue-emitting PeLED by thermal evaporation.