A high-efficiency solution-deposited thin-film photovoltaic device

The simple solution-based deposition approach that employs a non-carbon-containing and weakly coordinating solvent was investigated. The solution of spin-coating were prepared by mixing the appropriate quantities of each component solution to yield a targeted elemental composition in a single solution. An excess of Se in the solution was employed to enable the formation of a high Se ratio material and to promote grain growth. Spin-coating was performed in a nitrogen-filled dry box by flooding the substrate surface with the appropriate solution and spinning at 800 rpm for 90 seconds. The films were then immediately dried and partially decomposed for 5 minutes at 290°C on a preheated hot plate, followed by a final heat treatment in the nitrogen-filled drybox at a selected temperature of between 400-525°C. It was observed that the facile formation of a precursor solution enables rapid and convenient access to the full CIGS compositional range.