Calculation of electronic transitions in CdS clusters associated with coumarin dye

Abstract

Complexes of nanocrystalline semiconductors with organic dye molecules are critical components of two main
types of third-generation solar cells: dye-sensitized solar cells and thin-film cells of a nanocrystal. These devices rely on efficient photo-induced charge transfer across the nanostructured organic-inorganic interface. To estimate the charge transfer during photoexcitations, the coumarin 153 (C153) molecule and its complexes with the [C153-Cd 4 S 1 ]
6+ and [C153-Cd 13 S 4 ] 18+ quantum dot clusters were considered. The electronic absorption spectrum of the quantum dot - coumarin 153 complexes was calculated by the time-dependent density functional TD DFT and the analysis of molecular orbitals involved in intense
transitions was performed. The data obtained show the absence of intense charge transfer bands and the appearance of long wavelength bands, which indicate an increase in the dipole moment of the complex.