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 (E-reorg) 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 I-2 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).