Charge and Energy Transfer in the Metal-free Indoline Dyes for Dye-sensitized Solar Cells

Metal-free indoline dyes for dye-sensitized solar cells were studied by employing quantum chemistry methods.Comparative study of the properties of both ground and excited states of metal-free indoline dyes for dye-sensitized solar cells revealed: (i) as the number of rhodanine rings increases, the energy di?erence betweenHOMO and LUMO decreases and there is a red shift in the absorption spectrum with the binding energyincreased, and the transition dipole moment decreased; (ii) Based on an analysis of charge di?erential density,we observed that the charge and energy are transfered from the phenylethenyl to the indoline and rhodaninerings; (iii) The electron-hole coherences are mainly on the indoline and rhodanine rings, and the exciton sizesare 30 and 40 atoms for indoline dyes with one and two rhodanline rings, respectively. These results serveas a good example of computer-aided design in metal-free indoline dyes for dye-sensitized solar cells.