High performance scalable and cost-effective thermoelectric devices fabricated using energy efficient methods and naturally occuring materials

Abstract

Various printing methods have recently been employed to manufacture thermoelectric generators. While providing a scalable alternative to manufacturing thermoelectric generators, these printing techniques consume excessive energy by using long-duration and high-temperature sintering to reduce the interfacial connections and grain boundaries between thermoelectric particles. We report an inexpensive and energy-saving technique for fabricating thermoelectric generator devices that can be employed for low-waste heat applications. This technique involves a synergistic approach, using a small amount of binder (0.05 wt%), a heterogenous distribution of thermoelectric particles of varying size, low temperature (120 °C) and short duration (30 min) curing, and application of uniaxial mechanical pressure (200 MPa) to reduce the grain boundaries and interfacial connection and to enhance electrical conductivity of thermoelectric composite films and thermoelements. In this work, we present a thermoelectric prototype fabricated on gold-coated Kevlar substrate using p-type chitosan-100 mesh Bi₀.₅Sb₁.₅Te₃ and n-type chitosan-100 mesh Bi composite inks. The dimension of a single thermoelement was 6.5 mm × 2.3 mm × 150 µm. The 9-couple planar device was able to produce a power output of 73 µW at a voltage of 26 mV, and at a current of 2.8 mA at a temperature difference of 40 K, which is sufficient to power wireless sensor devices. Using energy-efficient methods and naturally occurring materials (Bi and chitosan), this device achieved a power density of 566 µW/cm² for a temperature difference of 40 K matching the best reported power densities of printed thermoelectric devices fabricated using high temperature and long duration.