Substituent Effect of Chiraldiphenyl Salen Metal (M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II)) Complexes for New Conceptual DSSC Dyes

Abstract

The authors have designed and synthesized new chiral salen-type metal (M = Fe, Co, Ni, Cu, Zn) complexes (1-5) for new conceptual dyes (co-sensitizer or colorful multi-dyes) of DSSCs (dye-sensitized solar cells). The authors measured substituent effects on their absorption spectra and redox properties, and compared them with TD-DFT (time-dependent density functional theory) calculations. Electron withdrawing groups resulted in red-shift of ultraviolet-visible (UV-Vis) spectra. For the first time, the authors also proposed and confirmed the importance of substituent effects on their electric transition dipole moments, calculated by TD-DFT for designing dyes. Chemisorption for TiO 2 of the complex by carboxyl groups was confirmed by XPS measurement. In view of electronic properties, all compounds have the possibility to be dyes of DSSCs.

Photofunctions in Hybrid Systems of Schiff Base Metal Complexes and Metal or Semiconductor (Nano)Materials

“…However, there are problems, such as high cost, low absorption strength, dye regeneration due to narrow HOMO-LUMO gap and reduction of the electron injection rate into the semiconductor for example TiO 2 . Therefore, new building blocks based on chiral salen-type Cu (II) complexes with carboxyl groups attached to the ethylenediamine linker were synthesized by Yamane et al, Takahashi et al and Yamaguchi et al ( Figure 3 ) [ 33 , 40 , 41 ]. The carboxylic acid group function was to anchor the organometallic dye on the oxide surface.…”

“… Design of chiral salen-type Schiff base Cu(II) complexes having ( a ) halogen substituents (X, Y) or ( b ) extended π-conjugated system and ( c ) both of these features (* denotes an asymmetric carbon atom) [ 33 , 40 , 41 ]. …”

Computational studies of Ni(II) photosensitizers complexes containing 1,1′-bis(diphenylphosphino)ferrocene and dithio ligands

“…Then results of TD-DFT calculations carried out for the studied Ni(II) using CAM-B3LYP hybrid exchange correlation functional including long range corrections will be be presented [53]. This functional provided appropriate results in the investigations of nickel complexes [10,32]. The dichloromethane solvent effects were included by the mean of polarizable continuum model (PCM) [54] in DFT and TD-DFT calculations.…”

“…The analysis of the frontier molecular orbitals (FMOs) is very helpful to study electronic and electrochemical properties of the complexes, on which depend their DSSC functions [6,10,24,32]. This analysis allows the identification of the electronic transitions related to the appearance of bands in the electronic absorption spectra.…”