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 (Voc: 804–834 mV). Among the four dyes, DSSCs based on BTA-II, with a furan moiety and branched alkyl chain, showed the highest Voc (834 mV), a photocurrent density (Jsc) 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.