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

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 A(3)B based sensitizers received much attention in DSSCs. Herein, we reported A(3)B 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 A(3)B 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 (eta) of 5.11-5.40%. Therefore, design of diverse molecular structures pave the way for improved efficiency and durability of photovoltaic devices.