Enhanced thermoelectric performance in K0.87RhO2 thin films induced by changing ambient gases during pulsed laser deposition

K0.87RhO2 thin films were prepared by pulsed laser deposition on fused silica substrates under different ambient gases. Besides the usual forming gas for oxides (i.e., O2), N2, Ar, mixture of O2 + N2, mixture of O2 + Ar, and vacuum were used during deposition. Although the crystal structure remained the same for all films, their electrical and thermoelectric properties were modified significantly depending on the ambient gases. Compared with the film deposited under O2, the film deposited under N2 exhibits electrical resistances one order of magnitude smaller, while the film prepared in N2 + O2 shows 50% enhancement in Seebeck coefficients. Moreover, the thermoelectric power factor was enhanced more than 100% as the ambient gas changed to Ar. Origins of such improvements in thermoelectric performance were discussed from the point of view of crystal defects, such as oxygen vacancies. Our results suggest an efficient way to modify the performance of K0.87RhO2 thermoelectric materials.