Thermoelectric Materials and Devices
Thermoelectrics allow solid state conversion of a temperature gradient into electricity. Its performance is defined by its Figure of Merit, (to insert equation), which requires a material of high electrical conductivity and Seebeck coefficient, and low thermal conductivity. An ongoing challenge is to optimise the performance of thermoelectrics, as the increase in one or two of the abovementioned parameters typically results in the reduction of the other.
The field of thermoelectrics is receiving intense R&D interest, given its potential as energy harvesting devices.The field of thermoelectrics is receiving intense R&D interest, given its potential as energy harvesting devices.
We are currently working on the following aspects of thermoelectrics:
- Skutterudites. Skutterudites are a manifestation of the Phonon Glass Electron Crystal (PGEC) concept, which allow simultaneous increase of electrical conductivity and reduction of thermal conductivity, which is needed for improvement of the thermoelectric Figure of Merit. Our work on skutterudites predominantly work on doping of the CoSb3 skutterudite crystal, which through substitution or filling of the crystal lattice, results in a significant improvement of the Thermoelectric Figure of Merit
Ionic liquids and polymer electrolytes. Ionic liquids and polymer electrolytes have been demonstrated as energy conversion and storage elements. A systematic study on the potential of ionic liquids as electrochemical based thermoelectric materials have been carried out (https://link.springer.com/article/10.1007/s11664-016-4355-2)
Spin crossover metal (SCO) complexes. Spin crossover metal complexes respond to stimuli such as heat, light and pressure to induce a change in its magnetic spin state. It can be used as a component in a thermoelectric energy harvester, as the transition of its spin state is accompanied by a large change in entropy, and consequently, a large Seebeck coefficient, which can reach up to a few mV/K. It also has advantages of ease of synthesis and low cost, and is thus potentially suitable for large area, printable devices.
- Development of Thermo Electrochemical Device (TEC). We have developed the prototype of a TEC device containing a membrane which has effectively enhanced the power output by 3 orders of magnitude.
- Micro TEC Device. From our experience in materials and devices on TEC development, we are working on developing micro TEC device using semiconductor processing technologies. We hope to achieve ultrahigh power output on a miniature scale through this current work.