title: Architecture of the Interface between the Perovskite and Hole-Transport Layers in Perovskite Solar Cells.
abstract: The interface between the perovskite (PVK, CH3NH3PbI3) and hole-transport layers in perovskite solar cells is discussed. The device architecture studied is as follows: F-doped tin oxide (FTO)-coated glass/compact TiO2/mesoporous TiO2/PVK/2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-MeOTAD)/Au. After a thin layer of 4,4,4-trifluorobutylammonium iodide (TFBA) was inserted at the interface between PVK and Spiro-MeOTAD, the photovoltaic efficiency increased from 11.6-14.5 % to 15.1-17.6 %. TFBA (10 ppm) was added in the PVK solution before coating. Owing to the low surface tension of TFBA, TFBA rose to the surface of the PVK layer spontaneously during spin-coating to make a thin organic layer. The PVK grain boundaries also seemed to be passivated with the addition of TFBA. However, large differences in Urbach energies and valence band energy level were not observed for the PVK layer with and without the addition of TFBA. The charge recombination time constant between the PVK and the Spiro-MeOTAD became slower (from 8.4 to 280 μsec) after 10 ppm of TFBA was added in the PVK. The experimental results using TFBA conclude that insertion of a very thin layer at the interface between PVK and Spiro-MeOTAD is effective for suppressing charge recombination and increasing photovoltaic performances.
authors: Department Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino Wakamatsu-ku, Kitakyushu, 808-0196, Japan. masahiro-moriya@edu.life.kyutech.ac.jp.
authors: Masahiro
authors: M
authors: Moriya
authors: Department Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino Wakamatsu-ku, Kitakyushu, 808-0196, Japan.
authors: Daisuke
authors: D
authors: Hirotani
authors: Department Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino Wakamatsu-ku, Kitakyushu, 808-0196, Japan.
authors: Tsuyoshi
authors: T
authors: Ohta
authors: Department Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino Wakamatsu-ku, Kitakyushu, 808-0196, Japan.
authors: Yuhei
authors: Y
authors: Ogomi
authors: The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan. shen@pc.uec.ac.jp.
authors: Qing
authors: Q
authors: Shen
authors: Department Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino Wakamatsu-ku, Kitakyushu, 808-0196, Japan.
authors: Teresa S
authors: TS
authors: Ripolles
authors: Department of Applied Physics and Electronic Engineering, University of Miyazaki, Miyazaki, 889-2192, Japan.
authors: Kenji
authors: K
authors: Yoshino
authors: The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan.
authors: Taro
authors: T
authors: Toyoda
authors: Department of Electrical and Electronic Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
authors: Takashi
authors: T
authors: Minemoto
authors: Department Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino Wakamatsu-ku, Kitakyushu, 808-0196, Japan. hayase@life.kyutech.ac.jp.
authors: Shuzi
authors: S
authors: Hayase
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry*; D011211:Electric Power Supplies; D010087:Oxides / Q000737:chemistry*; D012993:Solar Energy; D013501:Surface-Active Agents / Q000737:chemistry; D014025:Titanium / Q000737:chemistry*
chemical_list: D064751:Ammonium Compounds; D017610:Calcium Compounds; D010087:Oxides; D013501:Surface-Active Agents; C059910:perovskite; D014025:Titanium
keywords: fluoride; grain boundary; passivation; perovskite; traps