A metallic hot-carrier photovoltaic device

Hot carrier solar cells overcome the fundamental limitations of conventional devices where charge carriers are photogenerated over a broad energy spectrum but rapidly lose energy to the lattice and are extracted at the lowest energy of the system. In a hot carrier photovoltaic cell, carriers are extracted at higher energies than the absorption threshold, and extraction proceeds sufficiently quickly to avoid dissipative energy loss. We demonstrate a new hot carrier photovoltaic device where a broad spectrum of light is absorbed in metallic layers tens of nanometers thick. Using a semiconductor quantum well resonant tunnel structure we demonstrate energy selective hot carrier extraction from the metal film and show a unique hot carrier signature in the device IV characteristics. Using a multiple beam experiment, we further prove that these carriers arise from a hot electron population rather than via internal photoemission; a necessary requirement for high efficiency photovoltaic operation.