First Principle Analysis of Charge Dissociation and Charge Recombination Processes in Organic Solar Cells

Abstract

The rates of charge separation and charge recombination processes for a class of small organic molecules employed as donors in bulk heterojunction solar cells have been obtained from first principles. The Fermi Golden Rule and Kubo’s generating function method for evaluating the Franck–Condon weighted densities of states have been employed, with equilibrium geometries, vibrational frequencies, and normal modes computed at density functional theory level. The comparative analysis shows that the most performing donor dye exhibits the highest rate of the photoinduced electron transfer step.