Photovoltaic effect in poly-dioctyl-phenylene-ethynylene-C60 cells upon donor and acceptor excitation -: art. no. 113506

We studied photovoltaic effect in poly-dioctyl-phenylene-ethynylene (PPE)-C-60 cells using photovoltage and photocurrent spectroscopy. We observe two-step photoexcitation dependence of open circuit voltage V-oc. Two values of V-oc are due to different Coulomb binding energies for carriers originated from excitons in PPE and C-60. Due to built-in potential between PPE and C-60 layers, carriers overcome this exciton binding energy and separate at the heterojunction. We describe our results by energy diagram, comparing exciton binding energies in donor and acceptor moieties.