Semiconducting properties of cold sintered V2O5 ceramics and Co-sintered V2O5-PEDOT:PSS composites

Recently we established a sintering approach, namely Cold Sintering Process (CSP), to densify ceramics and ceramic-polymer composites at extraordinarily low temperatures. In this work, the microstructures and semiconducting properties of V2O5 ceramic and (1-x)V2O5-xPEDOT:PSS composites cold sintered at 120 °C were investigated. The electrical conductivity (25 °C), activation energy (25 °C), and Seebeck coefficient (50 °C) of V2O5 are 4.8 × 10−4 S/cm, 0.25 eV, and −990 μV/K, respectively. The conduction mechanism was studied using a hopping model. A reversible metal-insulator transition (MIT) was observed with V2O5 samples exposed to a N2 atmosphere, whereas in a vacuum atmosphere, no obvious MIT could be detected. With the addition of 1-2 Vol% PEDOT:PSS, the electrical conductivity (50 °C) dramatically increases from 10−4 to 10−3 ∼ 10−2 S/cm, and the Seebeck coefficient (50 °C) shifts from −990 to −(600 ∼ 250) μV/K. All the results indicate that CSP may offer a new processing route for the semiconductor electroceramic development without a compromise to the all-important electrical properties.