Exploring the influence of electron donating/withdrawing groups on hexamolybdate-based derivatives for efficient p-type dye-sensitized solar cells (DSSCs)

A series of polyoxometalates (POMs)-based dyes with electron donating/withdrawing groups were investigated by using density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. The light harvesting efficiency (LHE), dye regeneration efficiency (DRE), charge recombination efficiency (CRE), holes injecting efficiency (HJE) and reorganization energy (Ereorg) were systematically evaluated. The maximum absorptions of the designed dyes with electron donating groups (systems 1–3) are red shifted comparing with those containing the electron withdrawing groups (systems 4 and 5). Different electron donating groups have significant differences on the binding energy of dye–(NiO)4 system. In the dye regeneration, the I2 interacts with the terminal oxygen of POM cluster. System 1 (–NH2) balances all parameters, and it may perform better than others. Therefore, the introduction of –NH2 into POM-based organic–inorganic hybrids may improve the performance of dye in dye-sensitized solar cells (DSSCs).