Doped organic single-crystal photovoltaic cells

Doped rubrene single-crystal photovoltaic cells were fabricated. Whole photocurrent generated in the pn-homojunction with the macroscopic area of 2 mm x 1 mm was confirmed to be collected through the p-doped homoepitaxial layer. A single-crystal substrate collected excitons to the pn-homojunction with the collection efficiency reaching 46%, owing to the long exciton diffusion length of 2.7 mu m.