(333f) Three Dimensional Carbon Nanotube Photovoltaics

Novel solar cell architectures, which increase power output compared to traditional two dimensional designs, are desirable for the coming years. We introduce a three dimensional photovoltaic device with vertically aligned carbon nanotube pillars coated with photoactive materials to create a solar cell. The extra dimensionality of this cell, as added by the nanotubes, has been theorized to increase the energy generated over planar cells by up to four times. This energy increase is due to an increase in the interactions between photons and the photoactive material as the sun is at an off-normal angle to the cell substrate. This allows photons to ?pinball? between vertical faces of the carbon nanotube towers, greatly increasing the chances that a photon is absorbed rather than reflected away from the cell face. Prototypes of these cells have been made and, when the solar flux is at an off normal angle to the substrate, do show an increased power production much as theory predicts. Current work focuses on further characterizing this increase in power output over two dimensional cells and increasing the overall efficiency of these cells through processing parameters.