Comparative study on electronic structures and optical properties of indoline and triphenylamine dye sensitizers for solar cells

Abstract

The computations of the geometries, electronic structures, dipole moments and polarizabilities for indoline and triphenylamine (TPA) based dye sensitizers, including D102, D131, D149, D205, TPAR1, TPAR2, TPAR4, and TPAR5, were performed using density functional theory, and the electronic absorption properties were investigated via time-dependent density functional theory with polarizable continuum model for solvent effects. The population analysis indicates that the donating electron capability of TPA is better than that of indoline group. The reduction driving forces for the oxidized D131 and TPAR1 are slightly larger than that of other dyes because of their lower highest occupied molecular orbital level. The absorption properties and molecular orbital analysis suggest that the TPA and 4-(2,2diphenylethenyl)phenyl substituent indoline groups are effective chromophores in intramolecular charge transfer (IMCT), and they play an important role in sensitization of dye-sensitized solar cells (DSCs). The better performance of D205 in DSCs results from more IMCT excited states with larger oscillator strength and higher light harvesting efficiency. While for TPA dyes, the longer conjugate bridges generate the larger oscillator strength and light harvesting efficiency, and the TPAR1 and TPAR4 have larger free energy change for electron injection and dye regeneration.

DFT and TD-DFT study on structure and properties of organic dye sensitizer TA-St-CA

“…Similar results are also found for several dye sensitizers [19,[62][63][64]. The discrepancy between experiment and TD-DFT calculations may be attributed to DFT and solvent effects [61]. Though the discrepancy is existed, the TD-DFT calculations are capable of describing the spectral features because of the qualitative agreement of line shape and relative strength as compared with experiment.…”

“…The calculated isotropic polarizability of TA-St-CA is slightly less than that of D5 (510.6 a.u. [61]). This may be resulted from that the aromaticity of the phenyl group in conjugate bridge of TA-St-CA is stronger than that of thiophene group in D5, and then the electronic structure of phenyl group is more stable than that of thiophene group, thus the response of external field for TA-St-CA is weaker than that for D5.…”

Understanding the Electronic Structures and Absorption Properties of Porphyrin Sensitizers YD2 and YD2-o-C8 for Dye-Sensitized Solar Cells

“…Therefore, the substitution at ortho-positions of the meso-phenyls has slight effects on the geometry of porphyrins framework. In addition, the quasi-coplanarity between acceptor group (carboxylic acid moiety) and conjugate bridge is favorable for intramolecular charge transfer (IMCT) [64]. The twist between diarylamino group and porphyrin cycle, which results from the orbital hybridiazation of N in diarylamino group, limits the electron donating ability [48].…”

Quantum chemistry calculations of 2-aminopyrimidine-5-carbonitrile Dye Sensitizer for Solar Cells

“…They determine not only the strength of molecular interactions (long-range intermolecular induction, dispersion 16 . It has been found that the dye sensitizer hemicyanine system, which has high NLO property, usually possesses high photoelectric conversion performance.…”