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

Abstract

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 π-conjugated donor–π–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 π-spacer and also to attach the dye to a TiO2 surface. This study focuses on the effect of the π-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 ∆Ginject, light harvesting efficiency, intramolecular charge transfer, and electrochemical properties (chemical potential μ, electronegativity χ, and global hardness η). Moreover, the structure–properties correlation for all dyes is discussed. Our quantum calculations reveal that the dye based on furan as π-spacer (Dye-Fu) may represent a potential electron donor for use in DSSCs.