Photocurrent spectra of bilayers and blends of the organic donor-acceptor system CuPc/C_(60)

摘要

Photocurrent spectra and quantum efficiency are investigated in photovoltaic cells with the electron donor material Cu-phthalocyanine (CuPc) together with C_(60) as electron acceptor material. By a systematic variation of both layer thicknesses in bilayer devices with the main process of photocurrent generation at the donor-acceptor interface we found a significant influence on photocurrent generation due to optical interference effects and determined the optimum layer thicknesses for both materials. The effective dissociation interface is increased by introducing a 1 : 1 blend of both materials between the pure CuPc and C_(60) layers. The more extended active volume of exciton dissociation leads to higher quantum efficiencies (IPCE up to  85L?2%) of the photovoltaic effect in comparison to the heterojunction bilayer devices.