Eliminating high-dimensional defects by upward unidirectional crystallization for efficient and stable inverted perovskite solar cells†

Abstract

High-quality crystallization is the most effective way to eliminate high-dimensional defects. However, it remains a critical challenge for the perovskites grown on self-assembled monolayers. Here, a double-side treatment strategy is proposed and a tailor-made 4-fluoro-2-methoxybenzonitrile is used to maximize the difference in the nucleation driving force between top and bottom sides of perovskite, resulting in upward unidirectional perovskite crystallization. The high-dimensional defects of transverse grain boundaries, buried voids and amorphous regions are all eliminated, contributing to a power conversion efficiency of 26.4% (certified 26.0%). In addition, the encapsulated devices exhibited superior stability following ISOS-D-3 and ISOS-L-2 protocols, respectively.