Improvement of thermoelectric nanocomposite film through the inclusion of carbon nanofibers and graphene

Thermoelectric materials provide a particularly promising solution for converting waste heat into electricity. Bismuth telluride (Bi2Te3) is a widespread type of thermoelectric material due to its high performance at room temperature. However, challenges remain in enhancing its electronic and mechanical properties when fabricated into thin films. The progress of self-powered microdevices and sensors is contingent upon the development of high-performance and reliable thermoelectric materials in film form. These materials must be able to effectively convert thermal energy into electrical energy, especially in room temperature range, ensuring reliable and sustained operation of the devices. This study investigates the impact of incorporating graphene and carbon nanofibers (CNFs) into Bi2Te3 films to significantly improve both thermoelectric and mechanical performance. The films were prepared using a 3-electrode electrochemical deposition technique with optimized electrolyte solutions to ensure uniform and effective dispersion of graphene and CNFs. The addition of graphene substantially increased the electrical conductivity of the films, resulting in a 200% improvement compared to pure Bi2Te3. This enhancement is attributed to the exceptionally high electrical conductivity of graphene. Furthermore, the incorporation of CNFs led to a 100% increase in hardness and a 34% increase in Young's modulus. These mechanical improvements are due to the Hall-Petch effect, which limits plastic deformation, and the substantial reinforcing effect of CNFs within the Bi2Te3 matrix. This research demonstrates the potential of integrating graphene and CNFs to enhance the overall performance of Bi2Te3-based thermoelectric materials. The resulting materials exhibit improved thermoelectric and mechanical properties, making them more suitable for a variety of applications, including waste heat recovery and wearable electronics.