Co-sensitization of N719 with polyphenylenes from the Bergman cyclization of maleimide-based enediynes for dye-sensitized solar cells

The co-sensitization of N719 with conjugated polyphenylenes for dye-sensitized solar cells (DSSCs) was demonstrated. The conjugated polyphenylenes (6-BC and 7-BC), which contain two triphenylamine (TPA) groups as electron donors and carboxylic acids as adsorption groups, were prepared from thermally triggered Bergman cyclization polymerization of two maleimide-based enediynes, 6 and 7. Both the short-circuit photocurrent density (J(SC)) and the open-circuit voltage (V-OC) of the co-sensitized DSSCs were enhanced due to the increase in light harvesting and the retardation of electron recombination and dye aggregation when N719 was co-sensitized with the conjugated polyphenylenes. The co-sensitized (7-BC + N719) DSSC showed a high efficiency of 9.68% (V-OC of 750 mV, J(SC) of 18.18 mA cm (2) and FF of 0.71), exhibiting an improvement of 16% compared to the devices sensitized with N719 (PCE of 8.34%) alone under identical conditions.