Sulfur-annulated perylenediimide as an interfacial material enabling inverted perovskite solar cells with over 20% efficiency and high fill factors exceeding 83%

Abstract

Interfacial engineering is crucial for promoting the photovoltaic performance of perovskite solar cells (PSCs), especially planar inverted PSCs. In this study, sulfur-annulated perylenediimide (PDI)-based derivatives (denoted as PDI-T and PDI-V) with twisted molecular structures were developed for use as interfacial materials between the perovskite absorber and the C₆₀ electron transporting layer. Benefiting from the decent electron mobility and good electron extraction and transporting properties of the PDI derivative-based interfacial materials, the charge transport is improved and the charge recombination at the interface is mitigated in the inverted PSCs. As a result, an inverted PSC with the PDI-T interlayer material exhibits a maximum efficiency of 20.41% and an excellent fill factor (FF) of 83.63%, representing one of the best values achieved in inverted PSCs. The PDI-V-based device shows a comparable efficiency of 20.17% and an excellent FF of 82.98%. The efficiencies over 20% achieved in this study are among the highest values reported to date in methylamine-based inverted PSCs.