Theoretical studies on the spectroscopic properties of porphyrin derivatives for dye-sensitized solar cell application

Dye sensitizers play an important role in dye-sensitized solar cells (DSSCs). Owing to the synthetic challenge and cost of precious metal-complex dyes, increasing research has been focused on organic molecule dyes, porphyrin and light metal porphyrin dyes. In this paper, three natural porphyrin derivatives as dyes with the TiO2 nanoparticulate model are studied theoretically using density functional theory (DFT) approaches to explore their spectroscopic properties and application future in DSSCs. The detailed orbital components and absorption transitions of these porphyrin derivatives are analyzed from the calculated results. Key parameters of the short-circuit current density (J(sc)) including light harvesting efficiency (LHE), electron injection driving force (Delta G(inject)) and nonlinear optical properties (NLO) were discussed. In addition, the calculated values of open circuit photovoltage (V-oc) for these dyes were also presented. The tetrapyrrole macrocycle of porphyrin with central metals Mg or Zn can enrich the absorption strength greatly. Our research reveals that the Zn-porphyrin sensitizer can be used as a potential sensitizer for DSSCs due to its good electronic and optical properties and good photovoltaic parameters. This study is expected to understand natural dye sensitizers and assist the molecular design of new dyes for further DSSC improvement.