Perovskite Substrates Boost the Thermopower of Cobaltate Thin Films at High Temperatures

TL;DR

This study demonstrates that using perovskite substrates with transition metal oxides enhances the thermopower of cobaltate thin films at high temperatures by activating additional conduction channels through oxygen incorporation.

Contribution

It reveals that oxygen incorporation into perovskite substrates significantly boosts thermoelectric performance of cobaltate films at elevated temperatures.

Findings

Reversible oxygen incorporation activates p-type conduction.

Enhanced thermoelectric performance above 450°C.

Potential for high-temperature thermopower generation.

Abstract

Transition metal oxides are promising candidates for thermoelectric applications, because they are stable at high temperature and because strong electronic correlations can generate large Seebeck coefficients, but their thermoelectric power factors are limited by the low electrical conductivity. We report transport measurements on Ca3Co4O9 films on various perovskite substrates and show that reversible incorporation of oxygen into SrTiO3 and LaAlO3 substrates activates a parallel conduction channel for p-type carriers, greatly enhancing the thermoelectric performance of the film-substrate system at temperatures above 450 {\deg}C. Thin-film structures that take advantage of both electronic correlations and the high oxygen mobility of transition metal oxides thus open up new perspectives for thermopower generation at high temperature.