Ultra-low Thermal Conductivity of Nanogranular Indium Tin Oxide Films Deposited by Spray Pyrolysis

TL;DR

This study demonstrates that spray pyrolysis-deposited nanogranular indium tin oxide films have ultralow thermal conductivity, significantly lower than bulk ITO, due to nanostructure and porosity, making them promising for thermoelectric applications.

Contribution

It provides a new method to produce ITO films with ultralow thermal conductivity using spray pyrolysis, supported by theoretical modeling and experimental validation.

Findings

Thermal conductivity ~0.84 W/m·K at room temperature

Nanogranular structure causes enhanced phonon scattering

Potential for thermoelectric applications

Abstract

The authors have shown that nanogranular indium tin oxide (ITO) films, deposited by spray pyrolysis on silicon substrate, demonstrate ultralow thermal conductivity ~ 0.84 +/-0.12 Wm-1K-1 at room temperature. This value is approximately by one order of magnitude lower than that in bulk ITO. The strong drop of thermal conductivity is explained by nanogranular structure and porosity of ITO films, resulting in enhanced phonon scattering on grain boundaries. The experimental results were interpreted theoretically, employing Boltzmann transport equation approach for phonon transport and filtering model for electronic transport. The calculated values of thermal conductivity are in a reasonable agreement with the experimental findings. The presented results show that ITO films with optimal nanogranular structure may be prospective for thermoelectric applications.