Tunable Tribovoltaic Effect via Metal-Insulator Transition.

Yang, Ruizhe; He, Zihao; Lin, Shiquan; Dou, Wenjie; Wang, Zhong Lin; Wang, Haiyan; Liu, Jun · Nano Lett · 2022

basic_science · Level V

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Abstract

Tribovoltaic direct-current (DC) nanogenerator made of dynamic semiconductor heterojunction is emerging as a promising mechanical energy harvesting technology. However, fundamental understanding of the mechano-electronic carrier excitation and transport at dynamic semiconductor interfaces remains to be investigated. Here, we demonstrated for the first time, that tribovoltaic DC effect can be tuned with metal<i>-</i>insulator transition (MIT). In a representative MIT material (vanadium dioxide, VO<sub>2</sub>), we found that the short-circuit current (<i>I</i><sub>SC</sub>) can be enhanced by >20 times when the material is transformed from insulating to metallic state upon static or dynamic heating, while the open-circuit voltage (<i>V</i><sub>OC</sub>) turns out to be unaffected. Such phenomenon may be understood by the Hubbard model for Mott insulator: orders' magnitude increase in conductivity is induced when the nearest hopping changes dramatically and overcomes the Coulomb repulsion, while the Coulomb repulsion giving rise to the quasi-particle excitation energy remains relatively stable.