Regulating the crystallization of thermally evaporated perovskites for efficient near-infrared light-emitting diodes

Thermal evaporation of perovskite films holds considerable promise for the scalable manufacturing and pixel patterning of perovskite light-emitting diodes (PeLEDs). However, the performance of evaporated PeLEDs remains inferior to their solution-processed counterparts due to the lack of effective strategies to regulate perovskite crystallization during vacuum deposition. Here we address this challenge and achieve precise control over crystallization pathways. Dual-amide additives suppress premature perovskite phase formation during deposition and decelerate crystallization kinetics during post-annealing. We realize thermally evaporated near-infrared PeLEDs with a maximum external quantum efficiency of 25.0% for emission at 805 nm, and a T 50 lifetime of 23 h at a driving current density of 100 mA cm −2 . To show the advantages of thermal evaporation in pixelization, we realize monolithic dual-colour-emitting PeLEDs at 805 nm and 759 nm by integrating different PeLEDs on the same substrate and demonstrate dual-wavelength wearable pulse oximetry. This work provides insights into vacuum deposition crystallization dynamics and establishes a crystallization regulation methodology to advance evaporated perovskite optoelectronics.