A Study on the Intramolecular Energy and Charge Transfer of Triphenylamine dyes for Dye-Sensitized Solar Cells

  • Doctor Haining Tian, State Key Laboratory of Fine Chemicals, Dalian University of Technology, China
  • Assistant Professor Xichuan Yang, State Key Laboratory of Fine Chemicals, Dalian University of Technology, China
  • Doctor Ruikui Chen, State Key Laboratory of Fine Chemicals, Dalian University of Technology, China
  • Professor Licheng Sun, KTH School of Chemical Science and Engineering, Center of Molecular Devices, Physical Chemistry, Royal Institute of Technology, Sweden

    • Photosensitization of semiconductors by molecular dyes has attracted much attention to researchers since Graetzel and co-workers reported the new type dye-sensitized solar cells in 1991. In this study, we focus our interests on the intramolecular energy and charge transfer of the new synthesized Donor-(π-Bridge)-Acceptor dye, 2TPA-R, which contains two triphenylamine (TPA) units connected by vinyl group as the electron donor with rhodanine-3-aceticacid as the electron acceptor. Other two dyes, 2TPA and TPA-R, which consist of two TPA units connected by vinyl and a TPA unit linked with rhodanine-3-aceticacid, respectively, were synthesized as references. The molecular structures are shown in Figure 1. Intramolecular energy transfer of 2TPA-R was observed in CH2Cl2 solution by absorption and emission spectra (see Figure 2). Cyclic voltammetry and density functional theory (DFT) computations were employed to support the argument. When 2TPA-R was attached on TiO2 surface, both intramolecular energy and charge transfer were observed by laser flash and theory computations. To further study the effect of intramolecular energy and charge transfer on DSSC, the performance of DSSC based on 2TPA-R was measured and then compared with that of DSSC based on TPA-R (see Figure 3). The intramolecular energy transfer could improve the light harvest ability of the dye in DSSCs, and the intramolecular charge transfer process could effectively suppress the dark current in DSSCs. The result suggests that the intramolecular energy and charge transfer exhibited positive effect on DSSC performance.