Bright Fully Thermally Evaporated Quasi-Two-Dimensional Perovskite Light-Emitting Diodes

Quasi-two-dimensional (quasi-2D) perovskite light-emitting diodes (PeLEDs) are promising candidates for next-generation display technologies due to their excellent optoelectronic properties. Thermal evaporation offers advantages such as large-area uniformity and facile pixelation, making it a scalable approach for device fabrication. However, the relatively low brightness and external quantum efficiency (EQE) of thermally evaporated quasi-2D PeLEDs remain key challenges. Here, we report high-brightness, fully thermally evaporated quasi-2D PeLEDs enabled by in situ defect passivation. PEABr is coevaporated with CsBr and PbBr2 to construct the quasi-2D structure, and triphenylphosphine oxide is introduced to suppress low-dimensional phases and reduce defect density. The resulting perovskite emission films exhibit enhanced uniformity and optoelectronic quality. The optimized devices achieve a record luminance of 127,144 cd m–2 and an EQE of 7.18%, representing the highest performance among thermally evaporated quasi-2D PeLEDs reported to date. These findings demonstrate the great potential of thermal evaporation for scalable, high-performance perovskite display technologies.