Theoretical investigation of different functional groups effect on the photophysical performance of tricarbonylrhenium(I) complexes with tetrathiafulvalene derivative as dyes in dye-sensitized solar cell

Abstract

Tricarbonylrhenium(I) complexes (D1–D7) with π-extended tetrathiafulvalenes (exTTF: 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene) ligand including the phenanthroline unit (Phen) were investigated theoretically for getting potential dyes in dye-sensitized solar cell (DSSC). Complexes D2–D7 are different from D1 by introducing different functional groups (–NH2, –OH, –CH3, –F, –COOH, –NO2) attached on Phen ligand. To gain insight into their electronic structures, optical properties and potential applications for DSSC, density functional theory and time-dependent density functional theory (TD-DFT) were performed on these complexes. The good agreement between the experimental and TD-DFT calculated absorption spectra allowed us to get a detailed assessment of the main spectral features of these complexes by theoretical calculation. Based on the TD-DFT results, it is found that the optical properties of these complexes are affected by functional groups on Phen ligand. The absorption spectra are red-shifted with increasing the electron-withdrawing ability of introducing group in order: D7 > D6 > D5 > D1 > D4 > D3 > D2. In addition, comparing with the calculated related parameters of photoelectric conversion efficiency (η), we predict that D5 may have better performance as the dye sensitizer than other designed dyes.