Influence of spatial arrangements of π-spacer and acceptor of phenothiazine based dyes on the performance of dye-sensitized solar cells

• Three novel dyes PTA, PDTA and PTDA based on phenothiazine were designed and synthesized for DSSCs.
• The dye PTA with D–π–A framework has the highest value of open-circuit voltage.
• The dye PDTA with π–D–π–A framework has the lowest short-circuit current density.
• The DSSCs based on PTDA with A–π–D–π–A framework shows the highest efficiency of 6.82%.

Three phenothiazine based organic dyes PTA, PDTA and PTDA with D–π–A, π–D–π–A and A–π–D–π–A frameworks were designed and synthesized for the dye sensitized solar cells (DSSCs). Phenothiazine with octyloxyphenyl moiety acts as donor while thiophene and cyanoacetic acid units act as a π-spacer and an acceptor, respectively. The effects of the molecular structures of the dyes on the performance of the DSSCs were investigated systematically along with their photophysical and photoelectrochemical properties. The dye PTDA with A–π–D–π–A framework exhibited a better light harvesting capacity and an effective electron extraction pathway from the electron donor to the TiO2 surface, leading to an efficiency of 6.82% under 100 mW cm−2 light illumination, while the dyes PTA and PDTA with D–π–A and π–D–π–A frameworks delivered efficiencies of 6.34% and 5.12%, respectively.

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