Improving performance of sky-blue perovskite light-emitting diodes by triple additives

Abstract

A defect-passivation strategy is proposed to fabricate efficient sky-blue perovskite light-emitting diodes (PeLEDs) by using three additives: 2-(4-fluorophenyl) ethylamine hydrobromide (p-F-PEABr), lithium bromide (LiBr), and diethylamine hydrobromide (DEABr). This strategy not only significantly reduces the nonradiative recombination loss caused by defects, but also preserves the energy cascade transfer efficiency by maintaining the phase dispersion of the low dimensional phases. In addition to the universal additive p-F-PEABr, LiBr is introduced to improve perovskite crystallinity and passivate defects. The third additive DEABr employed as a spacer ligand partially replacing p-F-PEABr not only passivates the defects, thereby reducing the nonradiative recombination loss, but also preserves the phase dispersion of the low dimensional phases, thereby maintaining the energy cascade transfer efficiency. Moreover, Auger recombination is reduced and the radiation recombination efficiency is improved. As a result, the sky-blue PeLEDs achieve a maximum external quantum efficiency (EQE) of 7.82% with an emission peak at 484 nm and a maximum brightness of 5127 cd m⁻².