Acceptor substituent effect on triphenylamine-based organic dye sensitizers for DSSCs: quantum chemical study

Abstract

In this work, a series of triphenylamine (TPA)- based dye molecules (A1–A5) for dye-sensitized solar cells (DSSCs) application has been designed and screened. The electron donor contains TPA, thieno[3,2-b]thiophene, as the π-bridge, cyanoacrylic acid as electron acceptor based on donor–π-spacer–acceptor (D-π-A) as reference dye (3a). In order to enhance the tuning, effect of acceptor moieties was investigated at 3a dye. The electron acceptor effect of the substituent on the absorption spectra and photovoltaic (PV) properties has been investigated by the combination of density functional theory (DFT) and time-dependent DFT (TD-DFT) method approaches. Different exchange-correlation (XC) functionals were initially evaluated in order to establish a proper methodology for calculating the excited state energy of the 3a dye. Consequently, TD-ωB97XD method and 6-31G(d) basis set have used the comparison of experimental value. From the calculated results, it was concluded that the A4 (PO3H2) and A5 (SO2H) dyes are strongly grouped for more red-shift and electrons injected into semiconductor the conduction band edge of TiO2 was successful. It is expected that our research will pave a new method to design efficient organic D-π-A dye sensitizers in DSSCs.