Spectroscopic study of Na–TCNQ in a poly(ethylene oxide) matrix (TCNQ = 7, 7′, 8, and 8′ tetracyanoquinodimethane)

Abstract

X-ray Photoelectron Spectroscopy (XPS) and optical studies have been performed on P(EO)n –NaI–TCNQ (n = 1, 10) systems, obtained by means of a solid state reaction technique. The electron spectroscopy, the absorption in the ultraviolet visible near infrared range, and the infrared transmission findings allow us to conclude that the interaction among the polymer, the iodide, and the electron acceptor molecule results in the formation of the ion-radical salt Na–TCNQ and in the oxidation of I− to the metallic state. The presence within the examined specimens of crystalline and amorphous phases has been confirmed by the results of Differential Scanning Calorimetry (DSC) measurements. The optical, electronic, and thermal properties of the P(EO)n–NaI–TCNQ mixtures have then been correlated to the results of preliminary ac electrical transport investigations.