A comparison of the electronic and photovoltaic properties of novel twin-anchoring organic dyes containing varying lengths of π-bridges in dye-sensitized solar cells

Two novel donor acceptor π-conjugated (D-π-A) organic dyes have been engineered as sensitizers for applications in dye-sensitized solar cells. The derivatives of phenothiazine containing different numbers of thiophene units in the chromophore were synthesized to investigate the correlation between the number of π-bridge photovoltaic properties as photosensitizers for dye-sensitized solar cells. The organic dye with dithiophene units exhibited a higher molar extinction coefficient and more efficient electron injection from the dye to TiO₂ conduction band leading to an improved light harvesting efficiency. The solar-to-electricity conversion efficiency of 7.3% in the case of the bis(dithienyl) bridged dye with an open-circuit voltage of 0.636 V and short-circuit photocurrent density of 18.692 m A cm^-2, deriving from a higher absorption with respect to the mono (2,5-thienyl) containing dye, as conformed by incident photo-to-current conversion efficiency measurements.