Valence band offset in polymeric chains: The polythiophene/polyparaphenylene interface

Abstract

The valence band offset Δ E v at the interface between polythiophene and polyparaphenylene is derived from electronic structure calculations within the local-density approximation to the density functional theory. We use both the macroscopic electrostatic potential, and the core levels as reference energies to compute the alignment of the valence band maxima of the two polymers at the interface. When the spacing between polymeric chains in a simple orthorhombic lattice is large enough, we obtain ΔE v = 0.75 ± 0.05 eV, giving roughly equal valence and conduction band offsets. For smaller separations we find a small but sizable (≈ 0.15 eV) increase of Δ E v.