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.