Theoretical studies on organoimido-substituted hexamolybdates dyes for dye-sensitized solar cells (DSSC)

A series of POM-based organic-inorganic hybrids with different pi-conjugated bridges are investigated as sensitizers for application in dye-sensitized solar cells (DSSCs). A combination of density functional theory (DFT) and time-dependent DFT (TDDFT) approaches is employed. The effects of pi-conjugated spacer size and pi-conjugation length on the spectra of designed systems are demonstrated. The results show that the absorption spectra are systematically broadened and red-shifted with increasing sizes of the pi-conjugated spacer and the length of pi-conjugation. The theoretical examination was performed on the key parameters of incident photon-to-electron conversion efficiency (IPCE), light harvesting efficiency (LHE) and electron injection efficiency (Phi(inj)). The result suggests that system 2 with thieno[3,2-b] thiophene demonstrates a balance of the two crucial factors and may result in the highest IPCE of DSSCs. This study is expected to deepen our understanding of POM-based organic-inorganic hybrid dyes and assist the molecular design of new dyes for the further optimization of DSSCs. (C) 2013 Elsevier Ltd. All rights reserved.