Abstract
Because of the mismatch between the solar irradiance spectra and the photoactive layer absorption spectra, only a part of sunlight can be utilized, which fundamentally restricting the power conversion efficiency (PCE) of the polymer solar cells (PSCs). Ternary blend PSCs, with an additional third component, have become an effective approach to extend the absorption spectra and increase the mobility of the charge carriers. Herein, we select the middle band gap PBDTBDD as an electron donor and narrow band gap ITIC and wide band gap PC60BM as electron acceptors to construct ternary blends for simultaneously enhancing the absorption intensity and expanding the absorption band. The optical properties, morphologies, and the charge-/energy-transfer behaviors of the ternary blends are investigated. By attentively adjusting the ratio of the third component, ITIC, the ternary PSCs demonstrate an expanded light-response region and greatly enhanced J SC, giving an improved overall PCE of 10.36%, much higher than that of the binary counterparts based on PBDTBDD:PC60BM (6.63%) and PBDTBDD:ITIC (9.44%). These findings indicate that proper selection of donors and acceptors to construct absorption spectra-complementary ternary blend photoactive layers is an effective way to achieve high-performance PSCs.