Modulating the molecular configuration by varying linking bridge for double-anchored dye-sensitized solar cells

Three novel metal-free organic dyes (TPTZ1, TPTZ2, and TPTZ3) with an A-D-π-D-A configuration were synthesized and applied for dye-sensitized solar cells (DSSCs). The relationship between the photovoltaic properties and the different connection bridges of these organic dyes was studied systematically, showing that a strategical variation on the linkage ways of dithiophene can obviously affect the twisted degree of backbone and, thus, have a great effect on inhibiting the intermolecular aggregation. Compared with a bulky rigid group substituted on TPTZ3, introducing flexible side chains at suitable sites on the TPTZ1 and TPTZ2 seems to be a more effective strategy to achieve high photoelectric performance for double anchoring dye. Indeed, the DSSCs based on TPTZ2 exhibit a high efficiency of 7.50%, reaching 99% of an N719-based standard cell at the same condition. This study provides a new approach for highly efficient anti-aggregation organic sensitizers.