Zwitterionic Interlayer‐Directed Submicrometer Self‐Assembly for Efficient Vacuum‐Deposited Near‐Infrared Perovskite LEDs

ABSTRACT Vacuum‐deposited perovskite emitters provide precise control over thickness and composition, making them inherently compatible with established organic light‐emitting diode evaporation infrastructure. However, vacuum deposition suffers from limited crystallization control compared with solution processing, which usually results in suboptimal device performance. The external quantum efficiency (EQE) of near‐infrared vacuum‐deposited perovskite LEDs remains approximately 10%. In particular, vacuum‐deposited 3D perovskites typically undergo rapid nucleation and poor crystal growth, leading to defect‐rich films with low photoluminescence quantum efficiencies (PLQEs). Although various passivation strategies have been explored to mitigate defect densities, the underlying growth processes and crystallization mechanisms under vacuum‐deposition conditions remain insufficiently understood. Here we demonstrate an interlayer‐directed crystallization strategy in a sequential vacuum deposition process, where a zwitterionic interlayer, 5‐aminovaleric acid (5AVA), directs the self‐assembly of perovskite precursors into oriented submicron‐scale domains. This approach produces high‐quality perovskite films with significantly enhanced PLQE and improved morphology. Perovskite light‐emitting diode (PeLED) fabricated via this route achieves a record EQE of 16.6% with a high radiance of 224 W sr − 1 m − 2 . These findings establish interlayer‐directed crystallization as a promising strategy for efficient vacuum deposited PeLEDs, showing potential in industrial evaporation technologies.