High-Performance Dispenser Printed MA p-Type Bi_0.5Sb_1.5Te₃ Flexible Thermoelectric Generators for Powering Wireless Sensor Networks

Abstract

This work presents a novel method to synthesize p-type composite thermoelectric materials to print scalable thermoelectric generator (TEG) devices in a cost-effective way. A maximum ZT of 0.2 was achieved for mechanically alloyed (MA) p-type Bi0.5Sb1.5Te3 (8 wt % extra Te additive)-epoxy composite films cured at 250 °C. A 50% increase in Seebeck coefficient as a result of adding 8 wt % extra Te in stoichiometric Bi0.5Sb1.5Te3 contributed to the increase in ZT. To demonstrate cost-effective and scalable manufacturing, we fabricated a sixty element thermoelectric generator prototype with 5.0 mm × 600 μm × 120 μm printed dimensions on a custom designed polyimide substrate with thick metal contacts. The prototype TEG device produced a power output of 20.5 μW at 0.15 mA and 130 mV for a temperature difference of 20 K resulting in a device areal power density of 152 μW/cm(2). This power is sufficient for low power applications such as wireless sensor network (WSN) devices.

Printed flexible thermoelectric generators for use on low levels of waste heat

“…The Seebeck coefficient of n-and p-type composite films is 180 Â 10 À6 V K À1 and 280 Â 10 À6 V K À1 [16,17]. Electrical conductivity of n-and p-type composites films is 3000 S m À1 and 1300 S cm À1 [16,17]. Thermal conductivity of n-and p-type composites films is 0.25 W m À1 K À1 [16,17].…”

“…We also assumed that heat conduction is one dimensional. The Seebeck coefficient of n-and p-type composite films is 180 Â 10 À6 V K À1 and 280 Â 10 À6 V K À1 [16,17]. Electrical conductivity of n-and p-type composites films is 3000 S m À1 and 1300 S cm À1 [16,17].…”

“…Details of the synthesis of the composite materials and their thermoelectric properties can be found in [16,17]. For thermoelectric devices to be suitable for low power electronics, they must be able to provide a minimum potential voltage.…”

“…Electrical conductivity of n-and p-type composites films is 3000 S m À1 and 1300 S cm À1 [16,17]. Thermal conductivity of n-and p-type composites films is 0.25 W m À1 K À1 [16,17]. Based on the composite thermoelectric film properties and fixed design parameters we have plotted power output vs. thermo-element leg length for a temperature difference 20 K as shown in Fig.…”

“…In this work, mechanically alloyed (MA) Bi 2 Te 3 (with 1%Se)-epoxy and Bi 0.5 Sb 1.5 Te 3 (with 8 wt.% additional Te)-epoxy have been chosen as starting n-type and p-type thermoelectric composite slurries because of their high ZT values at room temperature [16,17]. This work focuses on design of TEGs based on the properties of these composites for practical low waste heat applications.…”