Fabrication and Evaluation of Sb2Te3/PVDF Hybrid Thermoelectric Films

Sammanfattning: Thermoelectric (TE) materials and devices have been extensively studied for harvesting waste heat energy. There is more interest to fabricate TE materials and devices at low cost and highly-efficient ways. Besides, TE materials and devices should be flexible and light-weight to address the requirements of emerging applications such as wearable TE power generators, health sensors, and powering small mobile wireless devices. To fabricate flexible and light-weight TE films with low cost and high-efficiency, organic- inorganic hybrid materials have been introduced. Organic-inorganic hybrid materials not only show the advantages of organic materials, such as good flexibility, light-weight, low cost, but also reflects the good TE properties of inorganic TE materials. The aim of this project was to synthesize and investigate the p-type hybrid TE films.Recently, many different methods and mechanisms have been tested to improve TE performance of materials. One of these mechanisms called defect engineering, which has been used to enhance TE performance by increasing the carrier concentration. Another approach can be the introduction of interfaces and grain boundaries which can improve TE performance by suppressing lattice thermal conductivity. In addition, nanomaterials and low-dimensional materials are also used for improving TE performance, classical size effect suppresses lattice thermal conductivity by limiting the mean free path, while quantum size effect increases the Seebeck coefficient by creating a clear electronic density of state function.In this project, flexible and free-standing TE films based on Sb2Te3 nanoplatelets/PVDF composites have been fabricated via doctor blading method. The SEM images of these films show that they are porous structures. The sizes of Sb2Te3 nanoplates are around 1 μm with hexagonal morphology. Porous and nano-sized structures are helpful for enhancing ZT of TE films. However, porous structures not only reduce thermal conductivity but also deteriorate electrical conductivity. The resistance results of the films with different ratio of Sb2Te3/PVDF showed that the existence of porous structures in the films deteriorates the $ of films, which is seen in samples with low PVDF content. Initial findings are promising and can pave the way to design TE-paste to generate active surfaces with easily applicable hybrid materials.