Thermoelectric Performance of 2D Tellurium with Accumulation Contacts

TL;DR

This paper demonstrates the high thermoelectric performance of 2D tellurium nanofilms, highlighting the role of accumulation contacts in improving carrier collection, with potential applications in energy harvesting and cooling.

Contribution

First report of excellent thermoelectric performance in 2D tellurium nanofilms and analysis of accumulation contacts for enhanced efficiency.

Findings

Room temperature ZT of 0.63 in 2D Te nanofilms

High power factor of 31.7 μWcm-1K-2

Accumulation-type contacts improve carrier collection

Abstract

Tellurium (Te) is an intrinsically p-type doped narrow bandgap semiconductor with excellent electrical conductivity and low thermal conductivity. Bulk trigonal Te has been theoretically predicted and experimentally demonstrated to be an outstanding thermoelectric material with high value of thermoelectric figure-of-merit ZT. In view of the recent progress in developing synthesis route of two-dimensional (2D) tellurium thin films as well as the growing trend of exploiting nanostructures as thermoelectric devices, here for the first time we report excellent thermoelectric performance of tellurium nanofilms, with room temperature power factor of 31.7 {\mu}Wcm-1K-2 and ZT value of 0.63. To further enhance the efficiency of harvesting thermoelectric power in nanofilm devices, thermoelectrical current mapping was performed with a laser as a heating source, and we found high work function metals such as palladium can form rare accumulation-type metal-to-semiconductor contacts to 2D Te, which allows thermoelectrically generated carriers to be collected more efficiently. High-performance thermoelectric 2D Te devices have broad applications as energy harvesting devices or nanoscale Peltier coolers in microsystems.