Ampholytic interface induced in situ growth of CsPbBr3 for highly efficient perovskite light-emitting diodes

Abstract

Morphology has important effects on the performance and working stability of metal halide perovskite optoelectronic devices. It is widely believed that a uniform and pinhole-free perovskite film with closely arranged small grains is an ideal morphology for realizing high electroluminescence (EL) efficiency. This work presents an ethanolamine (EA) interface for in situ induction of perovskite nucleation and growth. Meanwhile a Lewis base of Tween 80 (T80) is employed as the defect passivator to suppress the defects in the bulk film. Under the combined effect of EA and T80, the optimal luminescence device displays a low opening voltage of 2.4 V, a peak current efficiency of 44.32 cd A⁻¹, a maximum external quantum efficiency of 12.7%, a maximum brightness of 50 900 cd m⁻², and a prolonged operational lifetime of 4.5 h. The detailed investigation reveals the mechanism of the effect of the EA interface. The EA can interact with both the hole transporting layer poly(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and the perovskite emissive layer CsPbBr₃ together, acting as a connecting agent due to its special functional groups of hydroxyl and amine, thus inducing grain nucleation and growth. As a result, a compact and pinhole-free perovskite film was obtained by the introduction of EA. This work will give beneficial insight for in situ morphology control of perovskite grains.