Benzotriazole-Bridged Sensitizers Containing a Furan Moiety for Dye-Sensitized Solar Cells with High Open-Circuit Voltage Performance

Two new benzotriazole-bridged sensitizers are designed and synthesized ( BTA-I and BTA-II ) containing a furan moiety for dye-sensitized solar cells (DSSCs). Two corresponding dyes ( BTA-III and BTA-IV ) with a thiophene spacer were also synthesized for comparison. All of these dyes performed as sensitizers for DSSCs, and the photovoltaic performance data of these benzotriazole-bridged dyes showed a high open-circuit voltage (V_oc: 804–834 mV). Among the four dyes, DSSCs based on BTA-II , with a furan moiety and branched alkyl chain, showed the highest V_oc (834 mV), a photocurrent density (J_sc) of 12.64 mA cm⁻², and a fill factor (FF) of 0.64, corresponding to an overall conversion efficiency (η) of 6.72 %. Most importantly, long-term stability of the BTA-I , BTA-II , BTA-III , BTA-IV -based DSSCs with ionic-liquid electrolytes under 1000 h light-soaking was demonstrated, and BTA-II exhibited better photovoltaic performance of up to 5.06 % power conversion efficiency.