Spray coated silver nanowires as transparent electrodes in OPVs for Building Integrated Photovoltaics applications

The application of spray coated silver nanowires (AgNWs) onto OPVs for building Integrated Photovoltaics (BIPVs) is demonstrated. By using AgNWs with PEDOT:PSS, a transparent conductive layer was demonstrated on top of an P3HT:PCBM active layer with a sheet resistance of 30 Ω/⎕ for 90% transparency. This has been applied to two separate configurations; semi-transparent OPVs for solar glazing applications and OPVs onto an opaque substrate, namely steel. For the latter, a novel technique to planarise the steel substrate with an intermediate layer is also presented, with a substantial decrease in surface roughness reported to ensure that the substrate is smooth enough to use for OPV fabrication. The use of SU-8 as an intermediate layer reduced the surface roughness to RA=10 nm, which is one of the lowest values reported to date, and was achieved on a low cost substrate (DC01 low carbon steel) using solution processing.