Interfacial Carrier-Transfer Channel Optimization Based on Hydrogen Bonds for High-Performance Organic Solar Cells

Relieved interfacial carrier recombination grasps the core competitiveness for photovoltaic device performance improvement. Hydrogen bonds provide an ultrafast carrier-transfer pathway, which acts as a promising candidate for interfacial modification. Here, phosphotungstic acid (PWA) is introduced as a hydrogen bond-containing mediator to optimize carrier-transfer channels between active layers and hole transport layers. PWA substantially regulates the core-shell structure of primal poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) originating from the interaction between PSS and PWA. The resultant binary organic solar cell device presents obvious performance improvement. A power conversion efficiency of 16.9% (15.3% for reference devices) is achieved. Detailed device mechanism analysis proved that the hydrogen bond interaction accounts for the favorable tuning of energy levels, the effective increase in hole mobility, and the decrease in carrier recombination at the interface. This work provides a perspective to better understand the carrier-transfer mechanism of composite transport materials, which also provides guidance in optimizing carrier-transfer channels for the development of effective interfacial transport materials.