Temperature sensitivities of doped polyaniline nanoscale films on flexible substrates

There is a need to develop more sensitive and cheaper flexible temperature sensors and sensor arrays. In this work, sub‐100‐nm thick polyaniline films of different thicknesses and doping content, coated on flexible PET substrates were used to study the temperature sensing behavior. The material and electrical properties of the films were characterized. The temperature sensitivities, based on DC measurements, varied with the film thickness and the doping content, with the variations being more pronounced at lower thicknesses. Higher sensitivities were obtained with thinner films at lower doping levels and these values are significantly higher than those obtained in commercially available flexible temperature sensors and moreover, these sensitivities could be tuned over a wider range. A possible mechanism was proposed to explain the experimental results, which was supported by the values of the calculated phonon frequencies. AC studies were conducted to identify the transport mechanisms and the transport parameters were calculated. An optimum window of conductivity was needed to obtain high sensitivities and the sensitivities could be tuned by varying the film thickness and the doping content. These films did not show discernable change in resistance upon bending and could be used on curved surfaces. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013