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

• The novel dyes of POM-based organic–inorganic hybrids were designed for DSSCs.
• The absorption spectra of systems were systematically studied.
• The electron injection efficiency (Φinj) from dyes to TiO2 was evaluated.
• The light harvesting efficiency (LHE) of dyes was assessed.
• The incident photon-to-electron conversion efficiency (IPCE) of dyes was assessed.

A series of POM-based organic–inorganic hybrids with different π-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 π-conjugated spacer size and π-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 π-conjugated spacer and the length of π-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 (Φinj). 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.

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