Vacuum-Deposited\nBlue Inorganic Perovskite Light-Emitting\nDiodes

Abstract

Perovskite light-emitting diodes (PeLEDs) have drawn\ngreat research\nattention because of their outstanding electroluminescence performance\nby solution processing. PeLEDs made by thermal evaporation are relatively\nrarely explored but are compatible to existing organic light-emitting\ndiode industrial lines. Blue-emitting PeLEDs are all based on organic-containing\nperovskites, rather than more stable all-inorganic perovskites because\nof their poor solubility, too fast crystallization, uneven discrete\nfilms, and unattainable pure blue emission. Here, we report all-inorganic,\nvacuum-processed blue PeLEDs. High-throughput combinatorial approaches\nare employed to optimize Cs–Pb–Br–Cl composition\nin our dual-source co-evaporation system to achieve the balance between\nfilm photoluminescence and injection efficiency. The as-deposited\nperovskite films demonstrated excellent intrinsic stability against\nheat, UV-light, and humidity attack. A series of PeLEDs were obtained\ncovering the standard blue spectral region with a best luminance of\n121 cd/m² and an external quantum efficiency of 0.38%.\nWe believe that the vacuum processing strategy demonstrated here provides\na very promising alternative way to produce efficient and stable all-inorganic\nblue-emitting PeLEDs.