Conjugate spacer effect on molecular structures and absorption spectra of triphenylamine dyes for sensitized solar cells: Density functional theory calculations
writer：Jie Xu, Lei Wang, Guijie Liang, Zikui Bai, Luoxin Wang, Weilin Xu, Xiaolin Shen
keywords：TPA dyes, DSSC, DFT
source：期刊
specific source：SPECTROCHIMICA ACTA PART A
Issue time：2011年
The molecular structures and absorption spectra of triphenylamine dyes containing variable thiophene units as the spacers (TPA1–TPA3) were investigated by density functional theory (DFT) and timedependent DFT. The calculated results indicate that the strong conjugation is formed in the dyes and the length of conjugate bridge increases gradually with the increased thiophene spacers. The interfacial charge transfer between the TiO2 electrode and TPA1–TPA3 are electron injection processes from the excited dyes to the semiconductor conduction band. The simulated absorption bands are assigned to pi→pi* transitions, which exhibit appreciable red-shift with respect to the experimental bands due to the lack of direct solute–solvent interaction and the inherent approximations in TD-DFT. The effect of
thiophene spacers on the molecular structures, absorption spectra and photovoltaic performance were comparatively discussed and points out that the choice of appropriate conjugate bridge is very important for the design of new dyes with improved performance.