Gallium-Doped Zinc Oxide Nanostructures for Tunable Transparent Thermoelectric Films

Ga-doped ZnO (GZO) transparent nanostructured thin films were fabricated via the magnetron sputtering process, and the effect of the Ga doping level in Ga_xZn_1-xO on their thermoelectric performance was investigated. Nanostructured composite Ga_0.085Zn_0.915O could achieve a power factor up to 1428 μW/mK²at 850 K, which is one of the highest among the reported thin-film GZO and other metal oxides-based thermoelectrics. A corresponding thermoelectric generator module using GZO as n-type legs was fabricated to attain a maximum power output of 230 nW at ΔT = 138 K with an estimated power density of 19.1 mW cm^-2. First-principles calculations were performed to study the thermoelectric properties of GZO, showing that the calculated result is perfectly consistent with the experimental observation that the maximum power factor was achieved at around 8.5% Ga doping. In addtion, 10 nanostructured gallium-doped ZnO thin-film legs were fabricated for transparent thermoelectric modules. This work provides an excellent example to foresee the thermoelectric nanostructured thin-film material property through the theoretical simulation of materials, suggesting that modeling plays a big role in designing and formulating high-performance thermoelectric materials.