Density functional theory study of carbazole dyes: Potential application of carbazole dyes in dye-sensitized solar cells

Dyes applied in dye synthesized solar cells are an important class of organic compounds. In order to extension novel dyes, three organic dyes (TB-CH, TB-CB and DTB-CB) which contain hexyl and butyl moieties as a branch and thiobarbutiric acid moiety as an electron acceptor, connected by carbazole unit have been studied. We report the synthesis, molecular structures, and study of adsorption of dyes on TiO2 anatase by density functional theory (DFT). Molecular orbital analysis study indicated all dyes can give suitable electron injection from their LUMO orbitals to the TiO2 conduction band. Also, dyes were investigated by UV spectroscopy and cyclic voltammetry (CV). The synthesized dyes were characterized extensively by IR, 1HNMR, 13CNMR, mass spectroscopy and CHN analysis. Results of Photo physical, electrochemical properties and density functional theory investigation indicated TB-CH, TB-CB and DTB-CB have potential for application in dye sensitized solar cell. The adsorption energy of each dye/TiO2 complex was −1.05, −1.01 and −1.00 eV for TB-CH, TB-CB and DTB-CB, respectively.