Vacuum-evaporated lead halide perovskite LEDs [Invited]

Lead halide perovskites (LHPs) have made impressive progress in solid-state optoelectronics by virtue of their excellent electronic and optical features. In the past few years, the light-emitting diode (LED) adopting LHP emitters have reached a comparable level of external quantum efficiency (EQE) with organic and colloidal quantum dot LED counterparts. Apart from solution-processing, all-inorganic CsPbX3 LEDs can also be fabricated using thermal evaporation in a single run without breaking vacuum. In principle, all-evaporated LHP-LEDs in a vacuum demonstrate good uniformity and reliability in a large-area, especially full color applications where color pixelation is necessary, although their performance is still lower than that of the devices using hybrid film depositions. Herein, the understanding of vacuum-evaporated LHPs and their resulting LEDs, including the materials, film deposition and device issues, are reviewed. Additionally, guidelines toward high-performance devices and their prospects in the future are included.