Silole and selenophene-based D-π-A dyes in dye-sensitized solar cells: Insights from optoelectronic and regeneration properties

We report on the theoretical design of five new organic D-pi-A sensitizers (JA1-JAS) featuring silole and selenophene space pi-linker, and an evaluation of their performance for application in dye-sensitized solar cells (DSSCs). Their structural, spectral and electronic properties were investigated using density functional theory (DFT) and time-dependent (TD)-DFT calculations. We found that incorporation of a silole as a pi-bridge substituent in the five-membered heterocyclic dye, in particular to JA2 and JA4, remarkably improves the optical UV-Vis absorption spectra and achieves larger light-harvesting efficiency (LHE) relative to the conventional thiophene-based spacer (JA1), leading to a larger J(sc) response. Interaction of these two theoretically designed dyes JA2 and JA4 in combination with iodide electrolytes was calculated and the LHE is significantly larger than that of their isolated dyes, both contribute to improving the DSSC performance. Calculated results give insight into the optoelectronic properties of the rationally substituted pi-spacer D-pi-A sensitizers concerning their regeneration and applicability for DSSCs.