Bismuth telluride based efficient thermoelectric power generator with electrically conducive interfaces for harvesting low-temperature heat

Abstract

Nearly 50% of the heat released by various sources in the environment is found in the temperature range below 573 K. Thermoelectric generators (TEGs) offer a robust solid-state energy conversion mechanism to harvest this waste heat into useful electrical energy. To develop efficient TEGs, a prerequisite is to couple n- and p-type thermoelectric materials through metallic interconnect, with low specific contact resistivity (ρc). The realization of low ρc involves several critical factors, such as the chemical and mechanical stability, which should be carefully optimized to achieve consistent TEG performance under long-term operation. In the present work, we have demonstrated the concept of a graded interface layer to realize electrically conducive contacts in mechanically alloyed n-Bi2Te2.7Se0.3 and p-Bi0.5Sb1.5Te3 thermoelectric material (TM) having moderate figure-of-merit (zT). We have reproducibly achieved electric contacts with low ρc in these materials (∼59-71 μΩ-cm2) using a graded layer of Ni. Using the established approach, the conversion efficiency (ηexp) of 6.5% (±10%) is demonstrated for the temperature difference (ΔT) of 270 K. Achieved ηexp in the present work matches well with the simulated conversion efficiency (ηsim)∼7.0%, and is one amongst the best-reported efficiencies surpassing the state-of-the-art commercial modules.

Keywords

• Thermoelectric power generator
• Contact resistance
• Interface
• Conversion efficiency