1/f noise in polyaniline/polyurethane (PANI/PU) blends

We have investigated the electrical conductivity and the low-frequency noise of spin coated polyaniline/polyurethane (PANI/PU) films on different substrates (free, on ceramic, PVC and Teflon) and different compositions. The layer thickness is between 12 and 220 μm. The range in conductivity at room temperature is from 102 to 104 S/m and the sheet resistance is between 4 and 50 Ω. The fluctuations in the conductivity have a 1/f spectrum. The 1/f noise normalized for bias, frequency and unit area, Cus is proportional with the sheet resistance, Rsh.Our proposed model explains the proportionality Cus ∝ Rsh and the high value of the proportionality factor between Cus and Rsh. The typical elongated shape of the PANI component with a relative low number of noisy contacts between touching conducting elongated chains explains the strong noise in such materials.