Session: 14-01: Measurement Techniques and Thermophysical Properties in Micro/Nanoscale

Paper Number: 132609

132609 - Thermoelectric Properties of Stressed P-Doped Polycrystalline Hollow Nanotubes 

Abstract: 

Thermoelectric generators have the potential to efficiently convert waste heat into valuable electrical power. However, conventional thermoelectric materials face limitations in terms of efficiency, scarcity, high cost, and scalability, impeding their widespread adoption [1]. Nanoengineering techniques have emerged as a promising solution to enhance the thermoelectric properties of abundant and inexpensive materials like silicon and silicon-alloy compounds. Nevertheless, the integration of these nanostructures on a large scale, necessary for efficient waste heat recovery, remains a significant challenge [2].

Recently, a novel class of nano-enhanced materials in the form of extensive, paper-like fabrics composed of nanotubes has been developed, offering a cost-effective and scalable approach to thermoelectric power generation [2]. These fabrics are fabricated using an electrospun polimer as a template and a subsequent series of deposition and annealing steps. However, the fundamental properties of the building blocks of these fabrics, namely the p-type silicon nanotubes, have not been individually investigated to date. In addition, the correspondence between the properties of these individual nanotubes and the observed macroscopic properties of the fabric structure is also still unknown.

This study conducts electrothermal measurements using microfabricated calorimeters consisting in pairs of suspended nitride membranes in order to characterize the thermoelectric properties of these nanotubes, including the electrical conductivity, the thermal conductivity as well as the Seebeck coefficient. These properties are studied in the typical temperature operation range for thermoelectric energy harvesting (300-400 K) Furthermore, Raman thermography is employed in order to accounte for the effects of thermal contact resistances in the thermal conductivity measurements. Raman spectroscopy is also used to examine the residual mechanical stress in the nanotubes arising from the fabrication process. The relationship between this stress and the observed thermoelectric properties is studied. Additionally, this work investigates the laser light absorption within these hollow structures. Finally, the effects of SiGe alloy on the properties of the nanotubes are compared and discussed.

By understanding the interplay between the morphology, structure, and thermoelectric properties of the nanotubes, a pathway can be established for the development of more mechanically stable and efficient fabrics, with the potential for commercializing waste heat recovery through this technology.

 

References: 

[1] M. Haras and T. Skotnicki, “Thermoelectricity for IoT – a review,” Nano Energy, Oct. 2018, doi: 10.1016/j.nanoen.2018.10.013.

[2] Q. Zhang, K. Deng, L. Wilkens, H. Reith, and K. Nielsch, “Micro-thermoelectric devices,” Nat. Electron., vol. 5, no. 6, pp. 333–347, Jun. 2022, doi: 10.1038/s41928-022-00776-0.

[3] Morata et al. "Large-area and adaptable electrospun silicon-based thermoelectric nanomaterials with high energy conversion efficiencies" Nat. Comm. (2018), 4759, 9(1) doi:10.1038/s41467-018-07208-8

Presenting Author: Jose Manuel Sojo Gordillo University of Basel

Presenting Author Biography: Dr. Jose M. Sojo obtained his bachelor’s degree in Energy Engineering at the University of Malaga in 2016. After completing his master’s degree in Nuclear Engineering at the Polytechnical University of Catalonia (Barcelona) in 2018, he embarked on his doctoral thesis in the Nanoionics and Fuel Cells group at the Catalonia Institute for Energy Research (IREC). In this role, he focused on the fabrication and characterization of semiconductor nanostructures for thermoelectric applications. He successfully defended his thesis in October 2022.
Currently, Dr. Sojo holds a position at the Nanophononics group at the University of Basel as a postdoctoral researcher. He is now engaged in the study of thermal transport phenomena at the nanoscale and the investigation of thermal switching devices.

Authors:

Jose Manuel Sojo Gordillo University of Basel
Yashpreet Kaur University of Basel
Mercè Pacios Pujadó Catalonia Institute for Energy Research
Giulio De Vito University of Basel
Saeko Tachikawa National Institute of Advanced Industrial Science and Technology
Alex Morata Catalonia Institute for Energy Research (IREC)
Ilaria Zardo University of Basel