Photovoltaic and spectroscopic properties of bacteriochlorin-based photosensitizer: molecular approach

Abstract

The biophotovoltaic features of the porphyrin- and bacteriochlorin-based solar cells in different media were investigated through quantum chemistry calculations. The results show that a decrease in the chemical potential and electrophilicity facilitates the charge transfer process. Also, the bacteriochlorins have a lower energy barrier of electron injection than that of porphyrin, because of a longer charge transfer distance and less electron–hole overlap. Moreover, nonpolar solvents accelerate the free charge production, due to the favorable changes in the exciton radius and exciton binding. Improved spectroscopic properties are observed for the dyes in the solvent medium, which may be related to an increment in the probability of the electronic transition and reduced band gaps. Based on the simulated absorption spectra, bacteriochlorins are the preferred light-harvesting materials than porphyrin in the visible region. Moreover, the development of the push–pull model in the bacteriochlorin structure increases their energy conversion ability, due to advanced quantum chemistry reactivity properties. According to the final efficiency, bacteriochlorins are the preferred candidates in comparison with porphyrin to be applied in the dye-sensitized solar cells, in agreement with the experimental results.