Manipulating Crystallization and Deprotonation Reaction through Surface Engineering of ZnO for Bright and Stable Near-Infrared Perovskite LEDs.

Abstract

Perovskite light-emitting diodes (LEDs) have attracted significant attention owing to their rapidly increasing external quantum efficiencies (EQEs). However, achieving bright and operationally stable perovskite LEDs remains a great challenge. Here, we reveal that the most commonly used surface modifier of zinc-oxide (ZnO) electron-transport layer, polyethylenimine ethoxylate (PEIE), inhibits the perovskite nucleation by inducing in situ chemical reactions of perovskite precursor components, forming thermally unstable interfacial species and reducing long-term operational stability of resultant devices. We develop a surface-engineering strategy by using an ether-based polymer modifier to regulate perovskite crystallization kinetics and simultaneously suppress ZnO-induced deprotonation during long-term device operation. As a result, the optimized near-infrared (NIR) perovskite LEDs exhibit a maximum EQE of 24% and a peak radiance of 539 W sr-1 m-2, along with significantly enhanced operational stability. Furthermore, partial substitution of FA with Cs confirms the generality of this strategy, yielding bright NIR devices with an operational half-lifetime of 561 h at 20 mA cm-2.