Theoretical study of the effect of auxiliary acceptors insertion on phenothiazine-based dye DSSC photoelectrical properties

Phenothiazine (PTZ) based dyes have attracted the attention of many researchers in DSSC field. This work takes into account five novel metal-free organic sensitizers (designed based on a phenothiazine-based dye “SR1”) by studying the influence of auxiliary acceptor insertion on their optoelectronic, photovoltaic and chemical properties. This theoretical study was performed by using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to investigate the geometry, HOMO and LUMO energy, the molecular electrostatic potential (MEP) and the maximum wavelength absorption (λmax). Also, chemical and photovoltaic parameters were calculated. The conclusion of this study shows that the insertion of various auxiliary acceptors has a positive influence on UV-vis absorption spectra, energy gap, chemical and photovoltaic properties of reference dye, which can make the designed dyes good candidates for future DSSC practical applications. Furthermore, SR1-THDP and SR1-QTHZ molecules have shown the lowest band gaps with EGap=1,90 and 1,75 eV respectively and the highest wavelength values with λmax= 715 and 799 nm respectively.