Enhancing Efficiency and Stability of Organic Solar Cells by UV Absorbent

A new type of high boiling-point additive, UV absorbent benzophenone (BP), is reported which can simultaneously improve the efficiency and stability of fullerene and nonfullerene organic solar cells (OSCs). After the addition of BP, the power conversion efficiencies (PCEs) of nonfullerene OSCs based on FTAZ: ITIC-Th is increased from 8.5 to 9.4%, and is further increased to 10.3% by employing inverted geometry. Meanwhile, the photo-stability of nonfullerene OSC is improved. After illumination-aging, the OSCs with BP preserve 79% of the original PCEs, while the OSCs without additives or with 1,8-diiodooctane only preserve 65 and 58% of their original PCEs, respectively. In addition, BP can also work in fullerene-based OSCs. After the addition of BP, the efficiency and photo-stability of the OSCs based on PTB7-Th: PC71BM are simultaneously enhanced.