High Performance Shape-Conformable Thermoelectric Materials to Heat Sources

Abstract

Output power of thermoelectric generators depends on device engineering minimizing heat loss as well as inherent material properties. However, the device engineering has been largely neglected due to the limited flat or angular shape of devices. Considering that the surface of most heat sources where these planar devices are attached is curved, a considerable amount of heat loss is inevitable. To address this issue, here, we present the shape-conformable thermoelectric materials geometrically to surfaces of any shape by securing the flexibility of thin films or painting and 3D printing processes. We synthesized the molecular Sb2Te3 chalcogenidometallate and utilize them as ink solution for fabricating flexible thin films. At the same time, we prepared Bi2Te3-based inorganic pastes by using Sb2Te3 chalcogenidometallate as an additive for Bi2Te3-based thermoelectric particles, with ZT values of 0.5~0.7 for n-type and 1.0~1.2 for p-type materials that compete the bulk values. Devices directly brush-painted onto curved surfaces produced the high output power of 4.0 mW cm-2 under the temperature difference of 50 oC. Also, the shapes of 3D blocks printed by dispensing process were controllably varied to cube, circle, and half ring. Half-ring shaped thermoelectric 3D blocks were used to fabricate the cylindrical power generating module with three n-type and p-type pairs, which exhibited mW-level power under the temperature difference of 30~40 oC. These approaches pave the way to designing materials and devices that can be easily transferred to other applications.