Cost-Effective Approach to Fabricate Oxide-Based Bulk Thermoelectric Generator for Low-Grade Waste Heat Harvesting

Oxide materials are well explored in thermoelectric and optoelectronic device applications due to their wide range of tunable properties, thermal stability, compatibility with other materials, nontoxicity, and earth abundancy. As a result, it can often be integrated into devices, which facilitates the development of oxide-based thermoelectric generators at low cost. In this work, we synthesized Ba_xCoO₂ and graphene-doped In₂O₃ by solid-state reaction route and then incorporated them in thermoelectric generator for the first time. A preliminary 3-couple device is designed on a glass substrate. Here, the unique aspect is that graphite paint is used for the first time to make contact between oxide and metal electrodes instead of earlier used soldering and diffusion techniques, which prevents metals from diffusing in the oxide matrix. This device generates an open-circuit voltage of 30 mV whereas it produces an output power of 0.3 μW with power density of ≈15.5 nW cm⁻² for ΔT of 60 K, which is comparable to earlier reported metal-based Bi_0.5Se_1.5Te₃/Bi₂Se_0.3Te_2.7TE devices. Further, the physical dimensions of the generators can be adjusted and the temperature gradient can be increased to get the desired power. This work offers a promising strategy for the development of thick as well as thin thermoelectric generators at an affordable cost.