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

Abstract

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. © 2013 The Authors. Published by Elsevier Ltd. All rights reserved.