title: Cobalt Oxide (CoOx) as an Efficient Hole-Extracting Layer for High-Performance Inverted Planar Perovskite Solar Cells.
abstract: CoOxis a promising hole-extracting layer (HEL) for inverted planar perovskite solar cells with device configuration ITO/CoOx/CH3NH3PbI3/PCBM/Ag. The devices fabricated according to a simple solution procedure showed the best photovoltaic performance attaining power conversion efficiency (PCE) of 14.5% under AM 1.5 G 1 sun irradiation, which is significantly superior to those of materials fabricated with a traditional HEL such as PEDOT:PSS (12.2%), NiOx(10.2%), and CuOx(9.4%) under the same experimental conditions. We characterized the chemical compositions with XPS, crystal structures with XRD, and film morphology with SEM/AFM techniques. Photoluminescence (PL) spectra and the corresponding PL decays for perovskite deposited on varied HEL films were recorded to obtain the hole-extracting characteristics, for which the hole-extracting times show the order CoOx(2.8 ns) < PEDOT:PSS (17.5 ns) < NiOx(22.8 ns) < CuOx(208.5 ns), consistent with the trend of their photovoltaic performances. The reproducibility and enduring stability of those devices were examined to show the outstanding long-term stability of the devices made of metal oxide HEL, for which the CoOxdevice retained PCE ≈ 12% for over 1000 h.
authors.affiliation: Research Institute for Electronic Science, Hokkaido University , N21, W10, Kita-ku, 001-0021, Sapporo, Japan.
authors.forename: Ahmed Esmail
authors.initials: AE
authors.lastname: Shalan
authors.affiliation: Research Institute for Electronic Science, Hokkaido University , N21, W10, Kita-ku, 001-0021, Sapporo, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Oshikiri
authors.affiliation: Department of Applied Chemistry & Institute of Molecular Science, National Chiao Tung University , 1001 Ta Hsueh Road, Hsinchu 30010, Taiwan.
authors.forename: Sudhakar
authors.initials: S
authors.lastname: Narra
authors.affiliation: Department of Applied Chemistry & Institute of Molecular Science, National Chiao Tung University , 1001 Ta Hsueh Road, Hsinchu 30010, Taiwan.
authors.forename: Mahmoud M
authors.initials: MM
authors.lastname: Elshanawany
authors.affiliation: Research Institute for Electronic Science, Hokkaido University , N21, W10, Kita-ku, 001-0021, Sapporo, Japan.
authors.forename: Kosei
authors.initials: K
authors.lastname: Ueno
authors.affiliation: Department of Applied Chemistry & Institute of Molecular Science, National Chiao Tung University , 1001 Ta Hsueh Road, Hsinchu 30010, Taiwan.
authors.forename: Hui-Ping
authors.initials: HP
authors.lastname: Wu
authors.affiliation: Research Institute for Electronic Science, Hokkaido University , N21, W10, Kita-ku, 001-0021, Sapporo, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Research Institute for Electronic Science, Hokkaido University , N21, W10, Kita-ku, 001-0021, Sapporo, Japan.
authors.forename: Xu
authors.initials: X
authors.lastname: Shi
authors.affiliation: Department of Applied Chemistry & Institute of Molecular Science, National Chiao Tung University , 1001 Ta Hsueh Road, Hsinchu 30010, Taiwan.
authors.forename: Eric Wei-Guang
authors.initials: EW
authors.lastname: Diau
authors.affiliation: Research Institute for Electronic Science, Hokkaido University , N21, W10, Kita-ku, 001-0021, Sapporo, Japan.|Department of Applied Chemistry & Institute of Molecular Science, National Chiao Tung University , 1001 Ta Hsueh Road, Hsinchu 30010, Taiwan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Misawa
keywords: cobalt oxide; hole-extraction layer; perovskite solar cell; photoluminescence; photovoltaic devices