Abstract

A general theory of triboelectric nanogenerators (TENGs) is presented for an arbitrary geometric setup consisting of two electrodes, a fixed dielectric, and a moving dielectric [1]. The two dielectric materials have opposite charges. Optimization of power output is computed for a general periodic movement of the TENG. The developed Fourier theory is then used to address spherical triboelectric nanogenerators. The power output is optimized in terms of TENG parameters for two cases: (I) Assuming a uniform charge density on the electrodes and, more correctly, (II) assuming a uniform electric potential on the electrodes. A benchmark with exact results and other numerical methods shows the present boundary-element method’s advantage in accuracy and computational speed. In the second part of the talk, contact electrification and tribovoltaics [2] are discussed. I will present a Tsu-Esaki approach for tunneling-assisted contact electrification [3] and a microscopic tight-binding model for contact electrification in solid-solid and solid-fluid systems [4].

[1] J. Gravesen, M. Willatzen, J. Shao, and Z. L. Wang, “Quantitative Calculation of Output Power and Spherical Triboelectric Nanogenerators, Chapter 6 in Handbook of Triboelectric Nanogenerators, Springer, 2023.
[2] M. Willatzen, Z. Zhang, and Z. L. Wang, “Theory of tribovoltaics: Direct current generation at a p-n semiconductor interface,” Accepted for publication in Physical Review X Energy (2024).
[3] M. Willatzen and Z. L. Wang, “Contact electrification by quantum-mechanical tunneling”, Research (Science Partner Journal) Article ID 6528689, 11 pages, doi: 10.34133/2019/6528689 (2019).
[4] M. Willatzen, L. C. Lew Yan Voon, and Z. L. Wang, “Quantum theory of contact electrification for fluids and solids,” Adv. Funct. Mater. 2020 1910461, p.1-8.

Brief Biography: 

Dr. Morten Willatzen is a Senior Full Professor at the Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences. He was previously employed as a Full Professor at the Department of Photonics Engineering, Technical University of Denmark (2012-2017) and the Mads Clausen Institute, University of Southern Denmark (2004-2012). From 2000-2004 he was employed as Associate Professor at the Mads Clausen Institute, University of Southern Denmark. From 1995-2000 he was employed as a senior scientist at Danfoss A/S working on applications in thermo-fluid systems and flow measurement. From 1994-1995, he was a postdoctoral fellow at the Max-Planck Institute for Solid-State Research, Stuttgart working in the group of Professor Manuel Cardona.
Morten Willatzen holds an Honorary Professorship at the Mads Clausen Institute, University of Southern Denmark. He received his MSc degree in physics and mathematics in 1989 from Aarhus University and the PhD degree in theoretical physics from the Niels Bohr Institute, University of Copenhagen. Morten Willatzen’s research interests include solid-state physics, mathematical physics, piezoelectricity, electronic band structures, and more recently, triboelectric nanogenerators and contact electrification. Morten Willatzen is the author of three books: ‘’The k.p Method’’ published by Springer in 2009, ‘’Separable Boundary-Value Problems in Physics’’ published in 2011 (both co-authored with Lok C. Lew Yan Voon) and “Piezoelectricity in Classical and Modern Systems” published by IOP in 2024. Morten Willatzen has authored more than 10 book chapters and 350 papers in international journals and proceedings