Theoretical design of organoimido-substituted hexamolybdates with different electron donors for dye-sensitized solar cells

•Novel hexamolybdates dyes were designed with different electron donors.•The absorption spectra of substituted hexamolybdates dyes remarkably red shift.•The theoretical examination was performed on the key parameters.•Dye 6 containing a biTT unit has the largest λmax at 733 nm and shows a higher Jsc.•These dyes are promising candidates to obtain high performance solar cell materials.

Novel organoimido-substituted hexamolybdates dyes were designed by introducing 3,4-ethylenedioxythiophene (EDOT) or thienothiophene (TT) unit as electron donor based on [Mo6O18(MBTH)]2−. The electronic structures, absorption spectra and transition natures of designed systems have been theoretically investigated according to density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. Compared with dye 1, the absorption spectra of these designed organoimido-substituted hexamolybdates dyes exhibit both strong and broad absorptions from 400 to 800 nm, as well as remarkably red shift owing to the long π-conjugated bridge and high delocalization. Especially for dye 6, which contains a biTT unit, it has the largest maximum absorption wavelength (λmax) at 733 nm and may show a higher short-circuit current density (Jsc) as it possesses higher light harvesting efficiency (LHE) and reasonable driving force (ΔERP). Our work reveals that the designed molecule 6 is promising candidate for high performance solar cell materials.

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