Enhancing the stability of the polymeric Lewis-base-assisted dual-phase 3D CsPbBr3–Cs4PbBr6 perovskite by molecular engineering and self-passivation

Abstract

Inorganic metal halide perovskites have attracted attention for use in next-generation perovskite light-emitting diodes (PeLEDs) due to their excellent optical performance. However, the performance of most PeLEDs is influenced by surface defects and carrier diffusion properties. Herein, we present a facile and effective approach to form a self-ordered macromolecular intermediate phase by incorporating high molecular weight Lewis base polyvinylpyrrolidone (HM-PVP) within perovskite films. The synergistic effect of thermodynamically controlled perovskite grain growth and grain boundary passivation enables the formation of a highly cross-linked and bridged long-range-ordered polymer–perovskite composite. Furthermore, theoretical density functional theory calculations confirmed that CO groups in HM-PVP induce a shift of the electronic cloud toward the Pb²⁺ ions, resulting in a decrease in the perovskite surface energy and favoring thermodynamically modulated perovskite growth. Significantly, silver nanoparticle incorporation into the hole transport layer improves carrier transmission efficiency in HM-7% PVP bulk 3D perovskites and quasi-2D perovskite composite devices, exhibiting luminances of 12 000 cd m⁻² and 9500 cd m⁻² and current efficiencies of 11.5 cd A⁻¹ and 15.4 cd A⁻¹, respectively. Our results demonstrate that employing a polymeric passivating agent as a Lewis base adduct thermodynamically modulates perovskite growth and improves the perovskite film's quality for achieving highly stable PeLEDs.