Some chemical and electronic structures of the non-conjugated polymer poly(3,3′-phthalidylidene-4,4′-biphenylene)

Abstract

The valence band structure of poly(3,3′-phthalidylidene-4,4′-biphenylene) has been studied using ultraviolet photoelectron spectroscopy (UPS). This polymer exhibits a dielectric-to-metal phase transition under the influence of external forces and is therefore a good candidate for studying charge instabilities in conjugated polymers. Interpretation of the UPS spectra is facilitated using quantum chemical calculations based on the semi-empirical Austin Model 1 (AM1) method, for geometry optimization, and the valence effective Hamiltonian (VEH) method, for calculating the energy band structure diagram, from which the density of valence states (DOVS) in the solid material is derived. The calculated DOVs is in good agreement with the experimental UPS spectra, enabling an identification of features in the experimental data in terms of specific features in the energy band structure.