title: Charge Transfer Enhancement in the D-π-A Type Porphyrin Dyes: A Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) Study.
abstract: The electronic geometries and optical properties of two D-π-A type zinc porphyrin dyes (NCH₃-YD2 and TPhe-YD) were systematically investigated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to reveal the origin of significantly altered charge transfer enhancement by changing the electron donor of the famous porphyrin-based sensitizer YD2-o-C8. The molecular geometries and photophysical properties of dyes before and after binding to the TiO₂ cluster were fully investigated. From the analyses of natural bond orbital (NBO), extended charge decomposition analysis (ECDA), and electron density variations (Δρ) between the excited state and ground state, it was found that the introduction of N(CH₃)₂ and 1,1,2-triphenylethene groups enhanced the intramolecular charge-transfer (ICT) character compared to YD2-o-C8. The absorption wavelength and transition possess character were significantly influenced by N(CH₃)₂ and 1,1,2-triphenylethene groups. NCH₃-YD2 with N(CH₃)₂ groups in the donor part is an effective way to improve the interactions between the dyes and TiO₂ surface, light having efficiency (LHE), and free energy change (ΔGinject), which is expected to be an efficient dye for use in dye-sensitized solar cells (DSSCs).
authors.affiliation: Low Carbon Energy Institute, School of Chemical Engineering & Technology, China University of Mining & Technology, Xuzhou 221008, China. gjkang@cumt.edu.cn.
authors.forename: Guo-Jun
authors.initials: GJ
authors.lastname: Kang
authors.affiliation: Low Carbon Energy Institute, School of Chemical Engineering & Technology, China University of Mining & Technology, Xuzhou 221008, China. schaocumt@126.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Song
authors.affiliation: Low Carbon Energy Institute, School of Chemical Engineering & Technology, China University of Mining & Technology, Xuzhou 221008, China. renxf@cumt.edu.cn.
authors.forename: Xue-Feng
authors.initials: XF
authors.lastname: Ren
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D011166:Porphyrins
keywords: DFT; DSSCs; charge transfer; porphyrin