Cyano-functionalized small-molecule acceptors for high-efficiency wide-bandgap organic solar cells

Wide-bandgap non-fullerene acceptors (NFAs) are in high demand for constructing efficient ternary or tandem organic solar cells (OSCs), yet the scarcity of high performance wide-bandgap NFAs remains an important issue that need exploration and perfection. Here we designed and synthesized two NFAs (namely IDT-BC and IDT-C8-BC), featuring an indaceno[1,2-b:5,6-b ']dithiophene (IDT) core and electron-withdrawing benzo[c][1,2,5]thiadiazole-4-carbonitrile flanks. With optical bandgaps of 1.93 eV (IDT-BC) and 1.89 eV (IDT-C8-BC), respectively, they were both investigated for application in OSCs. By using polymer donor PBDB-T, single-junction OSCs based on two new NFAs are fabricated, giving power conversion efficiency (PCE) records of 6.3% (IDT-BC) and 7.3% (IDT-C8-BC). This work broadens the scope of developing new wide-bandgap NFAs with both high efficiency and easy accessibility.