Non-fullerene polymer solar cells based on a selenophene-containing fused-ring acceptor with photovoltaic performance of 8.6%

In this work, we present a non-fullerene electron acceptor bearing a fused five-heterocyclic ring containing selenium atoms, denoted as IDSe-T-IC, for fullerene-free polymer solar cells (PSCs). This molecule exhibits a low band gap (E-g = 1.52 eV), strong absorption in the 600-850 nm region and a high LUMO level (-3.79 eV). When a large band gap polymer J51 (E-g = 1.91 eV) was used as the donor, complementary absorption of the polymer donor and acceptor was obtained in the wavelength range of 350-850 nm. The solar cell based on J51:IDSe-T-IC gives a maximum PCE of 8.6%, with a high V-oc of 0.91 V, a J(sc) of 15.20 mA cm(-2) and a fill factor (FF) of 62.0%. Moreover, this performance is much higher than that of J51:PC71BM based PSCs under similar device fabrication conditions (PCE = 6.0%). The trade-off features of the J(sc) and V-oc existing in PSCs with fullerene acceptors have been minimized in the fullerene-free PSCs based on IDSe-T-IC and J51. The results demonstrate that fine-tuning the absorption and electronic energy levels of non-fullerene acceptors, and properly selecting a polymer donor to achieve complementary absorption, is a promising way to further improve the performance of the PSCs.