Self-assembled monolayers modified MoO 3 hole transport layer for enhanced organic solar cells performances

Abstract Molybdenum trioxide (MoO 3 ) is widely employed as hole transport layers (HTLs) in inverted organic solar cells (IOSCs). However, it still suffers from inadequate hole extraction. To address this challenge, we developed a novel surface modification strategy using a self-assembled molecules [4-(3,6-dimethyl-9H-carbazol-9-yl) butyl] phosphonic acid (Me-4PACz). The modification significantly enhances the hole extraction, reduces electrical resistance, and increases the work function of MoO 3 film. When applied to single-junction IOSCs based on the PM6:Y6 bulk heterojunction system, the modified MoO 3 HTL demonstrates a remarkable improvement in power conversion efficiency from 16.25% to 17.26%. Comprehensive characterization reveals that the Me-4PACz modification leads to substantial enhancements in both short-circuit current density ( J SC ) and fill factor. Notably, the modified devices also exhibit improved operational stability, suggesting the great potential interfacial engineering strategy for the high performance of IOSCs.