Improve Hole Collection by Interfacial Chemical Redox Reaction at a Mesoscopic NiO/CH3NH3PbI3 Heterojunction for Efficient Photovoltaic Cells

Ming Wei Lin, Kuo Chin Wang, Jeng Han Wang, Ming Hsien Li, Yu Ling Lai, Takuji Ohigashi, Nobuhiro Kosugi, Peter Chen, Der Hsin Wei, Tzung Fang Guo, Yao Jane Hsu

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11 Citations (Scopus)


Organometal-trihalide-perovskite-based solar cells have exhibited high efficiencies when incorporated into mesoscopic NiO (NiOnc) hole-transport layers. The integration of a NiOnc-perovskite heterojunction provides an inorganic alternative as a p-type contact material with efficient hole extraction for perovskite-based solar cells. Herein the origin of such highly efficient carrier transport is studied in terms of electronic, chemical and transport properties of a NiOnc-perovskite heterojunction with X-ray photoelectron spectra, ultraviolet photoelectron spectra, near-edge X-ray absorption fine structure spectra, a scanning transmission X-ray microscope, and calculations of electronic structure. A pronounced chemical redox reaction is found at an NiOnc-perovskite heterojunction such that PbI2 is oxidized to PbO with subsequent formation of hole-dopant CH3NH3PbI3–2δOδ at the heterojunction. The generation of hole-doping CH3NH3PbI3–2δOδ induced by the redox reaction at the NiOnc/perovskite heterojunction plays a significant role to facilitate the carrier transport, and thus enhances the photovoltaic efficiencies.

Original languageEnglish
Article number1600135
JournalAdvanced Materials Interfaces
Issue number17
Publication statusPublished - 2016 Sep 6


  • hole doping
  • interfaces
  • mesoscopic NiO
  • perovskites

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering


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