Non-Epitxaial GaAs/Organic Heterojunction Solar Cells With 830mV Voc

We present a GaAs heterojunction solar cell that achieves 830mV Voc without any epitaxial processing or external doping on a bulk wafer and has an area of 10mm^2. The device consists of a bulk, n-type GaAs wafer with sulfur passivation, 10 nm of spun coat TCTA, an organic p-type semiconductor, 5 nm of of evaporated WO3, and a spun-coat film of highly-conductive PEDOT:PSS for lateral current transport. This achieved voltage paves the way for thin-film devices that can achieve 20% efficiency with only low-capital intensity processing. Additional results gleaned in achieving this voltage include: a robust, reliable, residue-free GaAs passivation process, discovering processing conditions compatible with the passivation for forming heterojunctions, and learning about the importance of lateral conduction in non-traditional heterostructure devices.