Feasibility Study on Screen Printing as a Fabrication Technique for Low-Cost Thermoelectric Devices

Abstract

Conventional fabrication techniques for thermoelectric devices at present are expensive, time consuming, have low yield of material and come with a high failure rate for the devices. The proposed fabrication technology, screen printing of thermoelectric devices, offers a low-cost, flexible and quick manufacturing solution with a high yield of material which would help boost the market for miniature thin-film thermoelectric devices of high-voltage outputs, which can be utilised in numerous applications (e.g. energy harvesting, aerospace and automotive applications) where current devices are too expensive to be commercially attractive. The materials used for the prototype screen-printed devices were n-type Bi₂Te₃ and p-type Sb₂Te₃ thermoelectric materials, silver for the electrical contacts and glass and aluminium oxide as substrate materials. Five discrete stages were described and well defined as part of the ink formulation and screen-printing process: powder synthesis, material characterisation, the formulating stage, screen printing and finally heat treatment. A mathematical model was developed for the estimation of the electrical performance of screen-printed devices. Tests of screen-printed single-semiconductor pair samples proved that the fabrication technique proposed is promising, by demonstrating a power output of 16 μW and a voltage output of 2.1 mV for the single p-n junction at a ΔT of 20 °C across it, which compares well to existing systems in terms of voltage. The feasibility study has helped to not only define a promising fabrication method for thermoelectric devices but also identify the main challenges associated with it and realise that in many energy-harvesting applications the ZT of a thermoelectric device may not be as important as the thermal stability and longevity of it.