Vacuum-Deposited Blue Inorganic Perovskite Light-Emitting Diodes.

Perovskite light-emitting diodes (PeLEDs) have drawn great research attention due to their outstanding electroluminescence performance by solution processing. PeLEDs made by thermal evaporation are relatively rarely explored but compatible to existing OLED industrial lines. Blue-emitting PeLEDs are all based on organic-containing perovskites, rather than more stable all-inorganic perovskites because of their poor solubility, too fast crystallization, uneven discrete film and unattainable pure blue emission. Here we report all-inorganic, vacuum processed blue PeLEDs. High-throughput combinatorial approaches are employed to optimize Cs:Pb:Br:Cl composition in our dual-source co-evaporation system to achieve the balance between film photoluminescence and injection efficiency. As-deposited perovskite films demonstrated excellent intrinsic stability against heat, UV-light and humidity attack. A series of PeLEDs were obtained covering standard blue spectral region with a best luminance of 121 cd/m2 as well as an EQE of 0.38%. We believe the vacuum processing strategy demonstrated here provide a very promising alternative way to produce efficient and stable all-inorganic blue PeLEDs.