From Thermoelectric Powder Directly to Thermoelectric Generators: Flexible Bi2Te3 Films on Polymer Sheets Prepared by the Powder Aerosol Deposition Method at Room Temperature

Abstract

The powder aerosol deposition (PAD) method is a spray‐coating process to form dense, nanocrystalline ceramic films at room temperature without thermal treatment. Herein, the thermoelectric properties of PAD‐deposited Bi2Te3 films are investigated. The powders are deposited on rigid Al2O3 substrates and on flexible polymer sheets (Kapton and Mylar) attached to Kanthal foils. A low thermal conductivity of λ = 0.12 W m−1 K−1, an electrical conductivity of σ = 29.8 S cm−1, and a Seebeck coefficient of S = –145 μV K−1 are determined on Al2O3. To evaluate the flexibility of the Bi2Te3 films deposited on flexible polymer sheets, the electrical conductivity and the Seebeck coefficient are measured before, during, and again after bending. While the Seebeck coefficient remains unaffected by the bending process and the bending radius, the electrical conductivity deteriorates to some extent during bending. Subsequent measurements in the nonbent planar state reveal, however, that the conductivity is restored partially. Furthermore, first, flexible thermoelectric generators could be prepared and characterized. PAD offers enormous potential not only in the combination of Bi2Te3 films on polymer sheets without thermal treatment, but also for manufacturing flexible thermoelectric generators in general.