Optical characterization of plasma‐polymerized pyrrole‐N,N,3,5‐tetramethylaniline bilayer thin films

A capacitively coupled parallel‐plate reactor has been used to deposit plasma‐polymerized pyrrole (PPPy), plasma‐polymerized N,N,3,5‐tetramethylaniline (PPTMA), and plasma‐polymerized pyrrole‐N,N,3,5‐tetramethylaniline (PPPy‐PPTMA) bilayer thin films on to glass substrates at room temperature. To deposit the bilayer films, pyrrole monomer has been used as the mother material and N,N,3,5‐tetramethylaniline monomer has been deposited in different deposition time ratios after the pyrrole films were formed. Fourier transform infrared (FTIR) and ultraviolet–visible (UV–vis) spectroscopy techniques have been used to characterize the as‐grown thin films of about 500‐nm thick. The structural analyses by FTIR spectroscopy have indicated that the monomer has undergone the reorganization and the ring structure is retained during the plasma polymerization. From the UV–vis absorption spectra, allowed direct transition (E_qd) and allowed indirect transition (E_qi) energy gaps were determined. The E_qd for PPPy, PPTMA, and PPPy‐PPTMA bilayer films are found to be 3.30, 2.85, and 3.65 eV respectively. On the other hand, the E_qi for the same series are 2.25, 1.80, and 2.35 eV, respectively. From these results, it is seen that the energy gaps of the PPPy‐PPTMA bilayer films have been increased compared with the PPPy and PPTMA films. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011