D-π-A-π-D type benzothiadiazole-triphenylamine based small molecules containing cyano on the π-bridge for solution-processed organic solar cells with high open-circuit voltage

Two novel D-pi-A-pi-D structured small molecules composed of benzothiadiazole and triphenylamine were designed and synthesized. BDCTBT with cyano on the pi-bridge exhibited a deep HOMO energy level, resulting in an impressive V-OC of up to 1.04 V with a PCE of 3.85%, while non-cyano substituted BDETBT yielded a V-OC of 0.94 V and a PCE of 1.99%.