Examination of charge transfer dynamics using Time-Dependent Density Functional Theory

Abstract

In all solar cells and other devises, which harvest sun lights, charge transfer play a important role. The theoretical study of charge transfer using quantum mechanics is still inadequate. In this thesis we have done some theoretical investigation on charge transfer using time dependent density functional theory(TDDFT). Acceptor and donor are two important parts in charge transfer mechanism. The Polycyclic Aromatic Hydrocarbons (PAHs) molecules which can work as a donor in charge transfer mechanism also play a important role in Astrophysics. So we investigated the PAHs using TDDFT and extracted absorption spectra, for different PAHs varying in size, and match the results from pre-calculated absorption spectra(using TDDFT). Anthraquinone and its derivative are commonly use as dyes. Due to presence of anthraquinone ring, anthraquinone and its derivative make it eligible to work as acceptor. 1,5-diaminoanthraquinone(1,5-DAAQ) molecule which show the broad band observed in the visible region is due to the intramolecular charge transfer between the amino group and the anthraquinone ring. We calculated this broad band in visible region though our pick position doesn’t match with expeimental one. Using this CAM-B3LYP range separated exchange correlation functional we have shown charge oscillation in TCNE dimer and TCNE with Benzene systems where in each calculation one of the fragment of system has one extra electron.