Observation of room‐temperature out‐of‐plane switchable electric polarization in supported 3R‐MoS2 monolayers
Li Ma,
Liu Yang,
Yuqiang Fang,
Manzhang Xu,
Ruihuan Duan,
Vanessa Li Zhang,
Xuewen Wang,
Fuqiang Huang,
Menghao Wu,
Zheng Liu,
Ting Yu
Affiliations
Li Ma
School of Physics and Technology Wuhan University Wuhan China
Liu Yang
School of Physics and Wuhan National High Magnetic Field Center Huazhong University of Science and Technology Wuhan China
Yuqiang Fang
State Key Laboratory of High‐Performance Ceramics and Superfine Microstructure and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai China
Manzhang Xu
Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) Northwestern Polytechnical University Xi'an China
Ruihuan Duan
Centre for Programmed Materials, School of Materials Science and Engineering Nanyang Technological University Singapore Singapore
Vanessa Li Zhang
School of Physics and Technology Wuhan University Wuhan China
Xuewen Wang
Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) Northwestern Polytechnical University Xi'an China
Fuqiang Huang
State Key Laboratory of High‐Performance Ceramics and Superfine Microstructure and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai China
Menghao Wu
School of Physics and Wuhan National High Magnetic Field Center Huazhong University of Science and Technology Wuhan China
Zheng Liu
Centre for Programmed Materials, School of Materials Science and Engineering Nanyang Technological University Singapore Singapore
Ting Yu
School of Physics and Technology Wuhan University Wuhan China
Abstract Two‐dimensional (2D) ferroelectrics have attracted considerable attention due to their potential in the development of devices of miniaturization and multifunction. Although several van der Waals (vdW)‐layered materials show ferroelectricity, the experimental demonstrations of ferroelectric behavior in monolayers are very limited. Here we report the observation of room‐temperature out‐of‐plane switchable electric polarization in supported MoS2 monolayers exfoliated from 3R‐stacked bulk crystals under ambient conditions. Using in situ piezoelectric force microscopy and Kelvin probe force microscopy in a glovebox, we reveal that trapped water/ice molecules are responsible for this switchable electric polarization and this conclusion is strongly supported by theoretical simulations. It is worth noting that the water/ice trapping in the monolayers exfoliated from 2H‐stacked MoS2 crystals is not as much as that in 3R monolayers and, consequently, the out‐of‐plane electric polarization is missing there. Our findings indicate that monolayers with a trapped single layer of polar molecules might be emerging alternatives to 2D ferroelectrics. Furthermore, the stacking sequences may bring new properties and applications to 2D vdW materials not only when we stack them up but also when we thin them down.
