Facile synthesis and enhanced properties of acetylene carbon black conductive fillers in PVDF/bismuth telluride-based flexible thermoelectric materials

The development of flexible thermoelectric materials holds immense potential for applications in wearable electronics and energy harvesting devices. In this study, a ternary composite system comprising polyvinylidene fluoride (PVDF), acetylene carbon black (ACB), and Sb1.5Bi0.5Te3 (Bi–Te) was designed and investigated. The inherently insulating nature of PVDF was effectively transformed by incorporating ACB as a conductive filler, enabling the formation of percolation networks crucial for electron transport. A percolated threshold of ACB loading at ∼23 wt. % of PVDF provided a balance between electrical conductivity (∼4.0 S/cm) and mechanical flexibility. The addition of Bi–Te to the PVDF/ACB matrix significantly enhanced the Seebeck coefficient, which increased from 12 μV/K for the binary composite to 72 μV/K for the ternary composite with Bi–Te. This enhancement resulted in a peak power factor (PF) of 1.15 μW/mK2. This study underscores the potential of PVDF/ACB/Bi–Te composites as flexible thermoelectric materials, combining moderate thermoelectric performance with excellent mechanical properties.