X-ray photoemission spectroscopy and Fourier transform infrared studies of electrochemical doping of copper phthalocyanine molecule in conducting polymer

Abstract

A conducting polymer polythiophene (PT) film incorporated with copper phthalocyanine (CuPc), which was a highly functional molecule, was synthesized and characterized by Fourier transform infrared (FTIR) spectroscopy and x-ray photoemission spectroscopy (XPS). Electrochemical and casting processes were developed as a doping method of CuPc molecules in a PT film. In the XPS measurements of the CuPc doped PT, CuPc-origin peaks on the higher energy side appeared in the C 1s spectrum. The C 1s spectral profiles between electrochemically doped and cast samples were different in the higher binding energy region. S 2p and N 1s core-level spectra of CuPc doped compounds also showed the difference of the spectral profile between electrochemically doped and cast samples, which suggested the dopant-polymer interaction. A split of Cu 2p spectra indicates the charge transfer between CuPc and the polymer chains. In the FTIR measurements, characteristic vibrational modes to CuPc, in-plane, out-of-plane, and ring stretching modes were observed. A central metal-origin peak was also observed. New peaks at 1545 and 1680cm−1 suggest the polymer-PcCu linkage.