Perovskite Oxide Thermoelectric Module - A Way Forward

Abstract

In the era of renewable and sustainable energy, perovskite materials remain pioneers as energy harvesting materials, be it thermoelectric waste heat harvesting or photovoltaic solar cell application. Oxide perovskite material is an emerging thermoelectric material in solving energy shortage issues through waste heat recovery. The chemical and structural stabilities, oxidation resistance, and cost-effective and straightforward manufacturing process are a few advantages of the oxide-based thermoelectric materials. The perovskite thermoelectric materials and module thereof does not require any vacuum bagging for operation at high temperature, irrespective of the application environment. Perovskite CaMnO₃ displays a high Seebeck coefficient (S~-350 μV/K) due to correlated electron structure and low thermal conductivity (3 W m^-1 K^-1) but high electrical resistivity simultaneously. The electrical resistivity of CaMnO₃ can be tuned by electron doping at the Ca-site and Mn-site. Electron doping by substituting Mn³⁺ with trivalent rare-earth ions increases the carrier concentration in the CaMnO₃ system by partially reducing Mn⁴⁺ to Mn³⁺, improving electrical conductivity without altering the Seebeck coefficient. The dual-doped Ca_1-xYb_x/2Lu_x/2MnO₃-based n-type perovskite thermoelectric material showed a much higher power factor than undoped CaMnO₃ and proved to be an efficient perovskite from the application point of view. The thermoelectric module, in combination with CaMnO₃ as an n-type element and Ca₃Co₄O₉ or doped-Ca₃Co₄O₉ as the p-type element, is the most efficient device reported to date. The lab-scale power generation experiment is carried out for 4-element and 36-element modules consisting of perovskite Ca_1-xYb_x/2Lu_x/2MnO₃ as n-type elements and Ca₃Co₄O₉ as p-type elements. The results showed the challenges of up-scaling the perovskite module for high-temperature waste heat harvesting applications.