Enabling Oxidation Protection and Carrier-Type Switching for Bismuth Telluride Nanoribbons via in Situ Organic Molecule Coating

Jun Beom Park; Wei Wu; Jason Yingzhi Wu; Rijan Karkee; Theresa Marie Kucinski; Karen C Bustillo; Matthew M Schneider; David A Strubbe; Colin Ophus; Michael Thompson Pettes

doi:10.1021/acs.nanolett.3c02000

Enabling Oxidation Protection and Carrier-Type Switching for Bismuth Telluride Nanoribbons via in Situ Organic Molecule Coating

Nano Lett. 2023 Dec 27;23(24):11395-11401. doi: 10.1021/acs.nanolett.3c02000. Epub 2023 Dec 11.

Authors

Affiliations

¹ Center for Integrated Nanotechnologies (CINT), Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
² Department of Mechanical Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, United States.
³ Department of Physics, University of California, Merced, California 95343, United States.
⁴ National Center for Electron Microscopy (NCEM), Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
⁵ Materials Science in Radiation and Dynamics Extremes (MST-8), Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.

Abstract

Thermoelectric materials with high electrical conductivity and low thermal conductivity (e.g., Bi₂Te₃) can efficiently convert waste heat into electricity; however, in spite of favorable theoretical predictions, individual Bi₂Te₃ nanostructures tend to perform less efficiently than bulk Bi₂Te₃. We report a greater-than-order-of-magnitude enhancement in the thermoelectric properties of suspended Bi₂Te₃ nanoribbons, coated in situ to form a Bi₂Te₃/F₄-TCNQ core-shell nanoribbon without oxidizing the core-shell interface. The shell serves as an oxidation barrier but also directly functions as a strong electron acceptor and p-type carrier donor, switching the majority carriers from a dominant n-type carrier concentration (∼10²¹ cm^-3) to a dominant p-type carrier concentration (∼10²⁰ cm^-3). Compared to uncoated Bi₂Te₃ nanoribbons, our Bi₂Te₃/F₄-TCNQ core-shell nanoribbon demonstrates an effective chemical potential dramatically shifted toward the valence band (by 300-640 meV), robustly increased Seebeck coefficient (∼6× at 250 K), and improved thermoelectric performance (10-20× at 250 K).

Keywords: Bi2Te3; F4TCNQ; air-sensitive nanomaterials; surface doping; thermal conductivity; thermoelectric.