A low boiling-point and low-cost fluorinated additive improves the efficiency and stability of organic solar cells

Abstract

The application of high-performance organic solar cells (OSCs) requires high efficiency, high stability and low-cost devices. Herein, we propose a low boiling-point and low-cost additive 1,4-difluorobenzene (DFB) with a boiling point of 88.8 °C to optimize the morphology of the active layer of the OSCs based on conjugated polymer J71 as a donor and n-type small molecule m-ITTC as an acceptor. The DFB additive treatment enhances intermolecular π–π stacking of the photovoltaic materials, which is conducive to charge carrier separation and transport. The power conversion efficiency (PCE) of the OSCs based on J71:m-ITTC with the DFB additive treatment increased to 12.38% from 11.01% for the device without the additive treatment. Furthermore, the OSCs with the additive treatment also showed higher stability. The results indicate that 1,4-difluorobenzene will be a promising low cost additive for commercial application of OSCs.