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 degrees 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 pi-pi 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.