A Multifunctional Molecular Modifier Enabling Efficient Large-Area Perovskite Light-Emitting Diodes

Abstract

With rapid progress in perovskite light-emitting diodes (PeLEDs), the electroluminescence performance of large-area perovskite devices is increasingly important. We investigate why large-area performance lags behind that achieved in laboratory-scale devices, and found that defects in perovskite films – emerging from thermal convection during solvent evaporation and electronic traps formed during perovskite crystallization – are chief causes. Here we report a molecular modification strategy that simultaneously eliminates pinholes in perovskite layers by controlling the dynamics of film formation, and passivates the defects in perovskites by incorporating Br species, thereby preventing shorts and non-radiative recombination. The molecular modifier 1,3,5-tris (bromomethyl) benzene (TBB) also modulates the electronic structure of injection/transport materials to achieve improved charge injection and balanced charge transport. As a result, we demonstrate a 20 mm × 20 mm green perovskite nanocrystal LED that achieves an external quantum efficiency (EQE) of over 16%, the record efficiency for large-area PeLEDs. Our work opens a route to scaling perovskite LEDs.

Keywords: perovskite, light-emitting diodes, electroluminescence, molecular modifier, scalable fabrication