Electron transporting organic materials with an exceptional large scale homeotropic molecular orientation

Abstract

An electron transporting anthraquinone derivative demonstrated a stable large-scale homeotropic alignment on an open substrate surface, which substantially improved its charge carrier mobility. The electron mobility (μ_E) increased by two orders of magnitude from 3.2 × 10⁻⁴ cm² V⁻¹ s⁻¹ for the film without alignment to 1.2 × 10⁻² cm² V⁻¹ s⁻¹ for the homeotropically aligned film. A distinct enhancement in the UV absorption spectra of the films around the short wavelength range was observed to be associated with the molecular alignments. These alignments are less sensitive to the substrate under test. The anchoring force of the columnar stacks appears to be related to the nature of the material associated with the strong interaction between the molecules and substrate interface.