Chemical Redox of Mesoscopic NiO/CH3NH3PbI3 Perovskite Interfaces for High Efficient Solar Cell
Ming-Wei Lin1*, Kuo-Chin Wang2, Yu-Ling Lai1, Yu-Fu Wang3, Takuji Ohigashi4, KOSUGI, Nobuhiro4, Peter Chen2, Tzung-Fang Guo2, Yao-Jane Hsu1
1Nano science, National Synchrotron Radiation Research Center, Hsinchu, Taiwan
2Department of Photonics, National Cheng Kung University, Tainan, Taiwan
3Department of Physics, Tamkang University, Xinbei City, Taiwan
4Institute for Molecular Science, Ultra Violet Synchrotron Orbital Radiation, Nagoya, Japan
* presenting author:ming-wei lin,
Organometallic trihalide perovskite-based solar cells have exhibited the highest efficiencies to-date when incorporated into mesoscopic NiO (NiOnc). The success integration of NiOnc-perovskite figures out the sufficient photoinduced charge transfer from perovskite to NiOnc. However, less study provide a deep insight into the origin of such high efficient carrier transport in terms of electronic, chemical, and transport properties of perovskite and NiOnc heterojunction. Herein, the X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and scanning transmission X-ray microscopy (STXM) were employed. We found a pronounced chemical redox between perovskite-NiOnc heterojunction that PbI is oxidized to PbO while NiOnc reduced to metallic Ni. The interfacial redox at NiOnc/perovskite heterojunction not only reduce the work function of electrodes to facilitate the injection of holes, but also prevent the electron-hole pairs from recombination that leads to a markable enhancements of OPVs device performance. Meanwhile, CH3NH3I provides better filling of mesoporous NiOnc in which decrease the internal shunt between the NiOnc and perovskite interafce. With optimized heterojunction, chemical redox formation, close linkage of NiOnc at heterojunction, that paves the way for fabricating more stable, and high efficient NiOnc/perovskite-based solar cells.

Keywords: Mesoscopic NiO, CH3NH3PbI3 , PbO, Redox, high efficiency