Molecular engineering of bithiazole-based organic dyes with different electron-rich linkers toward highly efficient dye-sensitized solar cells

Abstract

Abstract A series of bithiazole-based dye sensitizers have been designed by employing various electron-rich moieties as π-spacer, which are based on the reported experimentally synthesized dye T-BT, to shed a light on the impact of both the nature and position of electron-rich moiety on the efficiency of dyes in DSSCs. To evaluate the efficiency of these dyes, various key parameters associated with overall conversion efficiency ( η ), including electronic and optical properties of free dyes are calculated, based on the computational methods. Besides, the dye/TiO 2 structures have been taken into account to investigate the interfacial features of the dye sensitizers adsorbed on TiO 2 semiconductor and explore the plausible mechanism of the electron injection. The results show that, compared with the reference dye, T-BT, the newly designed dyes with electron-rich moiety close to the donor group show a better efficiency for using in the DSSCs. Our calculations show that this result is valid for other electron-withdrawing auxiliary acceptor in the range of moderate to strong. Also, we found that the incorporation of pyrrolo [3,2 − b ] pyrrole (PP) unit in the π-spacer would be more favorable to enhance the efficiency of DSSCs, compared to other electron-rich groups. This computational study is expected to be a helpful guidance for the rational modification of organic dyes in future.