Thickness Dependent Direct Current Electrical Conduction in Plasma Polymerized Pyrrole Monolayer Thin Films

Abstract

The thickness dependent direct current electrical conduction mechanism in plasma polymerized pyrrole (PPPy) monolayer thin films has been discussed in this paper. A parallel plate capacitively coupled glow discharge reactor was used to deposit PPPy thin films at room temperature onto glass substrates. The Fourier Transform Infrared (FTIR) analyses showed that the spectrum of PPPy is very much different than that of the pyrrole monomer and indicated that the monomer has undergone the re-organization during the plasma polymerization. The current density-voltage (J-V) characteristics of PPPy monolayer thin films of different thicknesses indicated an increase in electrical conductivity in the thin films of lower thickness. It is seen that in the low voltage region, the current conduction obeys Ohms law while the charge transport phenomenon appears to be the space charge limited conduction (SCLC) in the higher voltage region. The permittivity, free charge carrier density, and the mobility of the charges of the PPPy monolayer thin films have been calculated from the experimental data of J-V characteristics and found to be 1.07 × 10-10 C2N-1m-2, (3.56 ± 0.01) × 1022 m-3, (4.4 ± 0.01) × 10-19 m2 V-1s-1 respectively.