A DFT/TD-DFT study on the possible replacement of Ru(II) with Fe(II) in phthalocyanine-based dye-sensitized solar cells

Abstract

Density functional theory and time-dependent density functional theory (DFT/TD-DFT) methods have been used to study the photo-voltaic and photophysicochemical properties of some metal-free and metal-containing phthalocyanine (Pc) derivatives (1–12) for application in dye-sensitized solar cells (DSSCs). The TD-DFT and molecular ground-state data were used to estimate the relative position of the TiO2 conduction band edge to the lowest unoccupied molecular orbital (LUMO) position (δp). The diffusion coefficients (Dπ), and oscillator strengths (f) at maximum absorption wavelengths of the molecules in the visible or near-infrared (near-IR) region were also estimated. Fluorescence emission (ϕf) and charge collection (ηc) efficiencies obtained using the method reported recently by our group were used in estimating the dyes’ incident photon conversion efficiency (IPCE). The estimated parameters have been used to characterize the dyes and evaluate their suitability for application in photo-voltaic technology both in gas phase and in acetonitrile. The overall results showed that iron(II) could be a possible substitute for ruthenium ion, as the choice metal ion for phthalocyanine-based DSSCs.