Influence of strong electron donating nature of phenothiazine on A3B- type porphyrin based dye sensitized solar cells

In this manuscript, we rationally designed A3B type hexyl-phenothiazine appended porphyrins utilized as sensitizer in redox liquid electrolyte results efficiency of 5.4% which is highest performance amongst A3B type sensitizers reported until now, hence design of diverse molecular structures pave the way for improved efficiency and durability of photovoltaic devices. [Display omitted] •Phenathiazine-porphyrin based sensitizers in A3B fashion designed for dye-sensitized solar cells.•DFT calculation suggests that LUMO close to conduction band of TiO2.•Power conversion efficiency of 5.40%, which highest among A3B type of porphyrin sensitizers. Structural modifications of porphyrin sensitizers have shown significant impact on incident photon to current generation whilst applied into dye sensitized solar cells. Nevertheless, various positional alterations of donor/acceptors attached porphyrin dyes reported until now in which A3B based sensitizers received much attention in DSSCs. Herein, we reported A3B type hexyl-phenothiazine appended porphyrins (G10 and G11) utilized as sensitizer with liquid redox electrolyte results the efficiency of 5.4% which is highest performance amongst A3B type sensitizers reported. Optical and electrochemical properties of G10 and G11 suggested that photoinduced intramolecular electron transfer mechanism occurred from donor hexyl-phenothiazine to acceptor acetic acid via porphyrin macrocycle. Density functional theory calculations revealed that lowest occupied molecular orbital of dyes close to the conduction band of TiO2 facilitates efficient electron injection from dye to nanoparticles. Incident photon to electron conversion efficiency (IPCE) spectra and J-V curve of dyesdepict broad band from 350 to 750 nm in the range of >50–55% as a result power conversion efficiency (η) of 5.11–5.40%. Therefore, design of diverse molecular structures pave the way for improved efficiency and durability of photovoltaic devices.