Simulating Dye-Sensitized TiO2 Heterointerfaces in Explicit Solvent: Absorption Spectra, Energy Levels, and Dye Desorption

Dye-sensitized solar cells (DSCs) represent a valuable, efficient, and low-cost alternative to conventional semiconductor photovoltaic devices. A deeper understanding of the dye/semiconductor heterointerface and of the dye-sensitized semiconductor/ electrolyte interactions are fundamental for further progress in DSC technology. Here we report an ab initio molecular dynamics simulation of a dye-sensitized TiO2 heterointerface “immersed” in an explicit water environment for an efficient organic dye, followed by TDDFT excited state calculations of the coupled dye/semiconductor/ solvent system. This new computational protocol and the extended model system allows us to gain unprecedented insight into the excited state changes occurring for the solvated dye-sensitized heterointerface at room temperature, and to provide an atomistic picture of water-mediated dye desorption.