[CCoE Notice] Seminar: 2D Ferroelectrets in Ultra-Thin Molybdenum Dioxide (MoO2) and Emergent Piezoelectricity * AH108, Agnes Arnold Hall * 10:30 am, Friday, January 24, 2020 * Anand B. Puthirath * Rice University

[Knudsen, Rachel W]

***** Seminar *****

Department of Electrical and Computer Engineering

Materials Engineering Program

Center for Integrated Bio and Nano Systems

  Friday, January 24, 2020

10:30am, Room: AH108 (Agnes Arnold Hall)

2D Ferroelectrets in Ultra-Thin Molybdenum Dioxide (MoO2) and Emergent Piezoelectricity

Anand B. Puthirath

Materials Science and NanoEngineering, Rice University



Abstract: Since graphene, a variety of two-dimensional (2D) materials have been fabricated in a quest for a tantalizing combination of properties and desired physio-chemical behavior. Two-dimensional materials that are piezoelectric, i.e. that allow for a facile conversion of electrical energy into mechanical and vice-versa, offer applications as sensors, actuators, energy harvesting, stretchable and flexible electronics, energy storage among others. Unfortunately, materials must satisfy stringent symmetry requirements to be classified as piezoelectric. Here we fabricate 2D ultra-thin single crystal molybdenum oxide (MoO2) flakes that exhibit unexpected piezoelectric-like response as MoO2 is centrosymmetric and should not exhibit intrinsic piezoelectricity. However, our group demonstrates 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, our material represents the first 2D electret material and suggests a route to artificially engineer piezoelectricity in 2D crystals. Specifically, we find that the maximum out-of-plane piezoresponse to be 0.56 pm/V 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.



Bio: Dr. Anand B. Puthirath received his PhD in physics from Cochin University of Science Technology (CUSAT), India, where he studied the roles of surface plasmons and conducting polymers in optoelectronics and energy storage. Dr. Puthirath completed his master’s degree in physics from the same school, where he specialized in modern optics, advanced mathematical methods for physicists and quantum field theory. After receiving his PhD, he joined the Tata Institute of Fundamental Research (TIFR), India, as a postdoctoral fellow, where, with the help of impedance spectroscopy, he investigated various types of relaxation phenomena in super-cooled glassy liquids near their glass transition temperatures (Tg). At TIFR, he also researched the potential material compositions for flexible solid electrolytes. In 2017, he received the national postdoctoral fellowship to pursue postdoctoral research at the Indian Institute of Science, Bengaluru. Dr. Puthirath joined Prof. Ajayan’s research group at Rice University as a SERB-Indo-US postdoctoral fellow in January 2018. His research at Rice has focused on magnetism and piezoelectricity in 2D materials. Other research interests include 2D materials-based sensors, mechanical properties of 2D and 3D structures, dielectrics, optoelectronics and low energy water splitting. Furthermore, research in the field of energy storage always excites him where the emphasis is on Li-S cells and supercapacitors.



Contact Prof. Dmitri Litvinov <litvinov at uh.edu<mailto:litvinov at uh.edu>> if you would like to meet with Dr. Puthirath.

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