High Performance and Flexible Polyvinylpyrrolidone/Ag/Ag2Te Ternary Composite Film for Thermoelectric Power Generator.

In this work, polyvinylpyrrolidone (PVP) coated Ag-rich Ag2Te nanowires (NWs) were synthesized by a wet chemical method using PVP coated Te NWs as templates, and a flexible PVP/Ag/Ag2Te ternary composite film on a nylon membrane was prepared by vacuum assisted filtration, followed by heat treatment. TEM and STEM observations of the focused ion beam prepared sample reveal that the composite film shows a porous network-like structure and that the Ag and Ag2Te exist as nanoparticles and NWs, respectively, both bonded with PVP. The Ag nanoparticles are formed by separation of the Ag-rich Ag2Te NWs during the heat treatment. For the composite film starting from a Ag/Te initial molar ratio of 6:1, a high power factor of 216.5 μW/mK2 is achieved at 300 K, and it increases to 370.1 μW/mK2 at 393 K. Bending tests demonstrate excellent flexibility of the hybrid film. A thermoelectric (TE) prototype composed of five legs of the hybrid film is assembled, and a maximum output power of 469 nW is obtained at a temperature gradient of 39.6 K, corresponding to a maximum power density of 341 μW/cm2. This work provides an effective route to a composite film with high TE performance and excellent flexibility for wearable TE generators.