Computational Designing of Triphenylamine Dyes with Broad and Red-shifted Absorption Spectra for Dye-sensitized Solar Cells using Multi-Thiophene Rings in π-Spacer

In this paper, we present the design of five new derivatives of triphenylamine dyes with variable thiophene rings (0–5) and shed light on their electrooptical and charge-injection properties. Computational techniques are used to study the effect of the thiophene moieties on the properties of interest, i.e., how the number of thiophene rings in π-conjugated systems influence the absorption spectra and electron injection of the dyes. The results show that the absorption spectra gradually became broad and red-shifted (384–542 nm) with the number of thiophene units. The effect of thiophene units on the performance of sensitizers in dye-sensitized solar cells is also determined. During theoretical examination, the electron injection efficiency (Φinject) and light harvesting efficiency (LHE) are determined. Results indicate that the selection of appropriate lengths of conjugated bridges in the dye sensitizer is very important in designing high-efficiency dyes.