title: Metal-electrode-free Window-like Organic Solar Cells with p-Doped Carbon Nanotube Thin-film Electrodes.
abstract: Organic solar cells are flexible and inexpensive, and expected to have a wide range of applications. Many transparent organic solar cells have been reported and their success hinges on full transparency and high power conversion efficiency. Recently, carbon nanotubes and graphene, which meet these criteria, have been used in transparent conductive electrodes. However, their use in top electrodes has been limited by mechanical difficulties in fabrication and doping. Here, expensive metal top electrodes were replaced with high-performance, easy-to-transfer, aerosol-synthesized carbon nanotubes to produce transparent organic solar cells. The carbon nanotubes were p-doped by two new methods: HNO3 doping via 'sandwich transfer', and MoOx thermal doping via 'bridge transfer'. Although both of the doping methods improved the performance of the carbon nanotubes and the photovoltaic performance of devices, sandwich transfer, which gave a 4.1% power conversion efficiency, was slightly more effective than bridge transfer, which produced a power conversion efficiency of 3.4%. Applying a thinner carbon nanotube film with 90% transparency decreased the efficiency to 3.7%, which was still high. Overall, the transparent solar cells had an efficiency of around 50% that of non-transparent metal-based solar cells (7.8%).
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Il
authors.initials: I
authors.lastname: Jeon
authors.affiliation: Department of Mechanical Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Clement
authors.initials: C
authors.lastname: Delacou
authors.affiliation: Department of Applied Physics, Aalto University School of Science, 15100, FI-00076 Aalto, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Kaskela
authors.affiliation: Department of Applied Physics, Aalto University School of Science, 15100, FI-00076 Aalto, Finland.
authors.forename: Esko I
authors.initials: EI
authors.lastname: Kauppinen
authors.affiliation: Department of Mechanical Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.|National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Maruyama
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.|Department of Mechanical Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.|University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Matsuo