Organic solar cells with a multicharge separation structure consisting of a thin rubrene fluorescent dye for open circuit voltage enhancement

Organic solar cells were fabricated by inserting a thin rubrene fluorescent dye between pentacene and fullerene heterojunction with a multicharge separation (MCS) structure, which was adopted to inherently further improve maximum open circuit voltage and power conversion efficiency. The morphology of organic films showed that a more surface roughness of pentacene film could be beneficial for an effective MCS interface, exciton dissociation, and charge carrier transportation. Moreover, a slight improvement of short-circuit current density when adding a 1 or 2 nm rubrene layer was also analyzed in detail based on external quantum efficiency spectra and optical transfer matrix theory.