Crystallization regulation and protection of quasi-2D perovskite film by copolymer to enhance the stability of perovskite light-emitting diodes

Abstract

Despite the high efficiency achieved at present, perovskite light-emitting diodes (PeLEDs) still suffer from poor device stability, even in quasi-two-dimensional (quasi-2D) perovskites with high stability potential. In this work, we propose using a copolymer, ethylene vinyl acetate (EVA), as an additive in anti-solvent to enhance the device stability of the PeLEDs. EVA regulates the crystallization process, which suppresses the phase change-induced material degradation to some extent. Moreover, the hydrophobic feature of EVA allows it to protect the perovskite layer against moisture and further increases the device stability. In addition, the ester group of EVA passivates the trap states in the perovskites. As a result, the EVA-modified PeLEDs show notably enhanced device stability (T80 of 80 min at relative humidity >45%) and device efficiency (22.9 cd A⁻¹) compared with the standard PeLEDs (47 min and 17.4 cd A⁻¹, respectively).