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 ( ρ c ). The realization of low ρ c 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 -Bi 2 Te 2.7 Se 0.3 and p -Bi 0.5 Sb 1.5 Te 3 thermoelectric material (TM) having moderate figure-of-merit ( zT ). We have reproducibly achieved electric contacts with low ρ c in these materials (∼59-71 μΩ-cm 2 ) using a graded layer of Ni. Using the established approach, the conversion efficiency ( η exp ) of 6.5% (±10%) is demonstrated for the temperature difference (Δ T ) of 270 K. Achieved η exp in the present work matches well with the simulated conversion efficiency ( η sim )∼7.0%, and is one amongst the best-reported efficiencies surpassing the state-of-the-art commercial modules.