By Josh Perry, Editor
Researchers at Osaka (Japan) University developed a cost-effective, large-scale, and highly-efficient flexible thermoelectric generator module (FlexTEG) that improves the thermoelectric conversion of waste heat from curved sources.
A flexible thermoelectric generator module created at Osaka University.
According to a report from the university, the flexibility stems from a change in direction of the top two electrodes of the module and the high-density packaging of semiconductors. This reduces the mechanical stress on the chips, improving their reliability. Researchers hope this enhanced efficiency can reduce the energy consumption of IoT devices.
“By mounting small thermoelectric (TE) semiconductor chips on a flexible substrate at high packaging density, the researchers achieved reliable and stable adhesion with electrical contacts between the chips and the flexible substrate, realizing efficient recovery (thermoelectric conversion) of waste heat,” the article explained. “In conventional nonflexible thermoelectric conversion modules, the top electrodes at the two sides were perpendicularly mounted to the other top electrodes, so the curvature of the module was limited. However, in this FlexTEG module, all of the top electrodes were integrated in parallel, providing flexibility when bent in any uniaxial direction.”
This design can be used for waste heat conversion up to 150°C.
The research was recently published in Advanced Materials Technologies. The abstract read:
“Recently, flexible thermoelectric generator (FlexTEG) modules using organic or thin film materials have gained much attention due to their potential applications for, for example, wireless sensors and wearable power. However, the performance of these modules is poor and still far from the requirement for energy harvesting.
“Here, the traditional semiconductor packaging technique is adapted to fabricate a large?scale FlexTEG, for use in energy harvesting on both planar and nonplanar surfaces. The module uses high?performance bismuth?telluride p? and n?type chips on a flexible thin plastic substrate. Using a unique isotropic design for mounting the chips, a FlexTEG module consisting of 250 p?n pairs is successfully fabricated on a 50 × 50 mm2 flexible substrate.
“The output power, mechanical strength, and bending properties are investigated at different temperature gradients and bending cycles. The module exhibits a maximum output power density of 158 mW cm−2 at dT = 105 K, corresponding to an efficiency value of 1.84%, which is comparable to a conventional bulk TEG.
“Mechanical tests reveal that the flexible module is reliable and stable during bending. These results open great potential for applications in portable, wearable, or implantable electronic devices.”
See the material in action in the video below: