The Subtle Structure Modulation of A 2 -A 1 -D-A 1 -A 2 Type Nonfullerene Acceptors Extends the Photoelectric Response for High-Voltage Organic Photovoltaic Cells.

Molecular structural modifications are utilized to improve the short-circuit current (J SC ) of high-voltage organic photovoltaics (OPVs). Herein, the classic non-fullerene acceptor (NFA), BTA3, is chosen as a benchmark, with BTA3b containing the linear alkyl chains on the middle core and JC14 fusing thiophene on the benzotriazole (BTA) unit as a contrast. The photovoltaic devices based on J52-F: BTA3b and J52-F: JC14 achieve wider external quantum efficiency responses with band edges of 730 and 800 nm, respectively than that of the device based on J52-F: BTA3 (715 nm). The corresponding  J SC increases to 14.08 and 15.78 mA cm -2 , respectively, compared to BTA3 (11.56 mA cm -2 ). The smaller Urbach energy and higher electroluminescence efficiency guarantee J52-F: JC14 a decreased energy loss (0.528 eV) and a high open-circuit voltage (V OC ) of 1.07 V. Finally, J52-F: JC14 combination achieves an increased power conversion efficiency (PCE) of 10.33% than that of J52-F: BTA3b (PCE = 9.81%) and J52-F: BTA3 (PCE = 9.04%). Overall, the research results indicate that subtle structure modification of NFAs, especially introducing fused rings, is a simple and effective strategy to extend the photoelectric response, boosting the  J SC and ensuring a high V OC beyond 1.0 V.