Fully Thermal‐Evaporated Perovskite Light‐Emitting Diodes with Brightness Exceeding 240 000 Nits

Abstract Thermally evaporated perovskite light‐emitting diodes (PeLEDs) have emerged as a promising technology for next‐generation display applications. However, achieving high luminance remains a critical challenge. In this study, a significant enhancement in the luminance of fully vacuum‐evaporated PeLEDs is demonstrated by optimizing both the crystallinity of perovskite films and hole injection efficiency. A lateral 0D/3D Cs ₄ PbBr ₆ /MA _x Cs _1‐x PbBr ₃ heterostructure is achieved via co‐evaporation of MABr (MA ⁺ = CH ₃ NH ₃ ⁺ ), CsBr, and PbBr ₂ . Theoretical calculations indicate that MAPbBr ₃ , with its lower formation energy, preferentially forms and serves as a nucleation site for the growth of high‐quality MA _x Cs _1‐x PbBr ₃ , significantly improving crystallization. Excess CsBr and PbBr ₂ react to form Cs ₄ PbBr ₆ , which passivates defects and confines excitons, thereby enhancing photoluminescence efficiency. The resulting perovskite films exhibit suppressed non‐radiative recombination. Additionally, hole injection and transport efficiency are improved through p‐type doping, ensuring sufficient carrier injection for high‐luminance emission. As a result, the optimized PeLEDs achieve a maximum brightness of 246, 211 cd m ^{− 2} , representing the highest level reported to date for thermally evaporated PeLEDs. These findings underscore the potential of thermally evaporated perovskites for high‐brightness display and lighting applications.