Hole-transport materials based on β-cyanodiarylethene core structure for efficient inverted perovskite solar cells

Abstract

Hole-transport materials (HTMs) are one of the most important components in inverted perovskite solar cells. HTMs can promote hole-extraction and transport; moreover, as the bottom surface, they directly affect the perovskite grain growth and perovskite film quality and have an influence on the photovoltaic performance and device stability. In this work, we designed and synthesized three β-cyanodiarylethene-based X-shaped organic molecules, which were differentiated by the end groups (CF₃, OMe, and tBu) (MT1–3). These compounds could be facilely synthesized with high yields and low costs. Experimental studies revealed that MT1 with CF₃ substitution possess good film morphology and strong defect passivation ability; moreover, it could strongly interact with perovskites through the functional groups, which could ameliorate the perovskite crystal quality and enhance interfacial charge transport. Inverted devices based on MT1 achieved a high power conversion efficiency of up to 22.25%, with excellent long-term stability as well as light stability.