We describe the use of single-wall carbon nanotube (SWNT) thin films as transparent and conducting electrodes for hole collection in poly(hexyl)thiophene-[6-6]phenyl-${\mathrm{C}}_{61}$ -butyric acid methyl ester (P3HT-PCBM) organic photovoltaics. We report a power conversion efficiency of 1%, with a fill factor of 0.3 and a short-circuit current of $6.5\mathrm{mA}∕{\mathrm{cm}}^2$ under $100\mathrm{mW}∕{\mathrm{cm}}^2$ polychromatic white light illumination measured in air. These values are comparatively higher than reference cells of similar thickness made on indium tin oxide (ITO) glass substrates. This is attributed to the three-dimensional nature of the interface between the SWNTs and the P3HT-PCBM nanocomposite. Our results indicate that solution processed SWNT thin films are a viable alternative to ITO for photovoltaic devices, eliminating an expensive vacuum deposition step in the fabrication of organic solar cells.

Field emission from graphene is challenging because the existing deposition methods lead to sheets that lay flat on the substrate surface, which limits the field enhancement. Here we describe a simple and general solution based method for the deposition of field emitting graphene/polymer composite thin films. The graphene sheets are oriented at some angles with respect to the substrate surface leading to field emission at low threshold fields $(\sim 4\mathrm{V}\mu {\mathrm{m}}^{-1})$ . Our method provides a route for the deposition of graphene based thin film field emitter on different substrates, opening up avenues for a variety of applications.