High-performance thermoelectric composites via scalable and low-cost ink processing

Abstract

Despite a significant increase in thermoelectric figure of merit zT achieved in the past two decades, the lack of scalable and low-cost device manufacturing methods has remained a major barrier to the large-scale adoption of thermoelectric devices for cooling and power generation. Here, we report a highly reproducible, facile, and cost-effective ink-based processing technique to fabricate thermoelectric composites with an exceptional room temperature zT of 1.3, which is by far the highest in materials processed using ink-based deposition methods. We found that the addition of tellurium (Te) to BiSbTe not only suppresses defects but also facilitates pressureless sintering and densification, optimizing the Seebeck coefficient and electrical conductivity while lowering thermal conductivity to achieve a high-performance thermoelectric device. The tuning of ink constituents leads to weighted mobility close to that of single-crystal BiSbTe while ensuring an optimal carrier concentration for maximizing the thermoelectric power factor. At a temperature difference of 97.5 °C, an in-plane thermoelectric device produces a high power density of 27 mW cm⁻². The highly scalable and inexpensive ink-based processing technique to manufacture devices with reproducible high thermoelectric performance near room temperature opens up enormous opportunities for using thermoelectrics to harvest low-grade waste heat to improve energy efficiency, reduce CO₂ emission, and enable environmentally friendly solid-state cooling and refrigeration without refrigerants or greenhouse gas emission.