2D Electrets of Ultrathin MoO2 with Apparent Piezoelectricity
Abstract
Since graphene, a variety of 2D materials have been fabricated in a quest for a tantalizing combination of properties and desired physiochemical behavior. 2D materials that are piezoelectric, i.e., that allow for a facile conversion of electrical energy into mechanical and vice versa, offer applications for sensors, actuators, energy harvesting, stretchable and flexible electronics, and energy storage, among others. Unfortunately, materials must satisfy stringent symmetry requirements to be classified as piezoelectric. Here, 2D ultrathin single‐crystal molybdenum oxide (MoO2) flakes that exhibit unexpected piezoelectric‐like response are fabricated, as MoO2 is centrosymmetric and should not exhibit intrinsic piezoelectricity. However, it is demonstrated that the apparent piezoelectricity in 2D MoO2 emerges from an electret‐like behavior induced by the trapping and stabilization of charges around defects in the material. Arguably, the material represents the first 2D electret material and suggests a route to artificially engineer piezoelectricity in 2D crystals. Specifically, it is found that the maximum out‐of‐plane piezoresponse is 0.56 pm V−1, which is as strong as that observed in conventional 2D piezoelectric materials. The charges are found to be highly stable at room temperature with a trapping energy barrier of ≈2 eV.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 06, 2020
- Source ID
- 10.1002/adma.202000006
Entities
People
- Amey Apte
- Anand B Puthirath
- David C. Moore
- Dmitri Litvinov
- Farnaz Safi Samghabadi
- Jordan A Hachtel
- Juan Carlos Idrobo
- Kosar Mozaffari
- Long Chang
- Nicholas R Glavin
- Pradeep Sharma
- Pulickel Ajayan
- Sandhya Susarla
Organizations
- Air Force Office of Scientific Research
- Air Force Research Laboratory
- Oak Ridge National Laboratory
- Office of Science
- Rice University
- United States Department of Energy
- University of Houston