New organic materials based on D--A structure for application in dye-sensitized solar cells

We used density functional theory at B3LYP level with 6-31G(d,p) basis set for all atoms to study the electrochemical, photovoltaic, and absorption properties of four new organic -conjugated donor--acceptor structures based on diketo-pyrrolo-pyrrole for use in dye-sensitized solar cells (DSSCs). Meanwhile, the cyanocarboxylic acid function of these compounds was used as electron acceptor to attract electrons from the donor unit via the -spacer and also to attach the dye to a TiO2 surface. This study focuses on the effect of the -spacer on structural, electronic, and photovoltaic properties including the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), energy gap, density of states (DOS), ultraviolet-visible (UV-Vis) absorption spectrum, free energy change of electron injection G(inject), light harvesting efficiency, intramolecular charge transfer, and electrochemical properties (chemical potential , electronegativity , and global hardness ). Moreover, the structure-properties correlation for all dyes is discussed. Our quantum calculations reveal that the dye based on furan as -spacer (Dye-Fu) may represent a potential electron donor for use in DSSCs.