Patent ID: 7772487

Claim:
A photovoltaic apparatus, comprising: an acceptor layer; a lower energy transfer layer; and a plurality of upper energy transfer materials, wherein the lower energy transfer layer is disposed between the acceptor layer and the plurality of energy transfer materials, wherein the upper energy transfer materials each have a bandgap that is higher than a bandgap of the lower energy transfer layer, and wherein there is a spectral overlap between an absorption band of the lower energy transfer layer and an emission band of one or more of the upper energy transfer materials, whereby excitons can transfer from the upper energy transfer materials to the lower energy transfer layer by Förster energy transfer, wherein the electronic levels of the lower energy transfer layer and acceptor layer are configured such that exciton splitting can take place at an interface between the lower energy transfer layer and the acceptor layer, wherein each of the upper energy transfer materials is characterized by a thickness that is greater than an exciton diffusion distance for that material, wherein the lower energy transfer layer has a thickness that is less than or equal to an exciton diffusion distance for the first energy transfer layer; wherein the upper energy transfer materials are arranged by molecular orbital levels in a cascading configuration to create cascading energy transfer events to transfer exitons from the upper energy transfer layers toward the lower energy transfer layer via Förster energy transfer.