Buried interface defect regulation enables efficient and stable inverted perovskite solar cells

Abstract

Defects in inverted perovskite solar cells (PSCs), especially those at the interface between the perovskite film and the underlying hole transport layer (HTL), critically impair the optoelectronic performance and long-term stability by inducing severe non-radiative charge-carrier recombination. Despite tremendous efforts such as developing self-assembled monolayers and incorporating aluminum oxide (Al2O3) nanoparticles at the interface, defects originating from the top-to-bottom crystallization of perovskite films remain a great challenge for inverted PSCs. Herein, a buried interface defect regulation strategy is proposed by incorporating p-chlorophenylacetic acid (p-ClPA) molecules at the perovskite/Al2O3 contact interface. The p-ClPA treatment induces enlarged grains, enhanced crystallinity, and improved optical and electrical properties, which are attributed to the modulated crystallization caused by interactions between p-ClPA and the perovskite precursors. Consequently, the optimized p-ClPA-regulated inverted PSCs deliver a champion power conversion efficiency (PCE) of 23.72% at an active area of 0.09 cm2. Moreover, the unencapsulated p-ClPA-modified device retains 92% of its initial PCE after 1000 h of continuous 1-sun equivalent illumination with maximum power point tracking (MPPT) at 50 °C in a nitrogen atmosphere, demonstrating outstanding operational stability.