Optical and electrical characterization of thin films based on anthracene polyether polymers

Abstract

Two new anthracene derivatives were characterized to improve the optoelectronic properties of π-conjugated anthracene polymers. The optical properties of the polymers were investigated by UV-visible absorption and photoluminescence (PL) spectroscopy. The energy bandgaps of anthracene-based polyether thin films were in the range 2.8–2.97eV. Green emission (504nm) was observed for anthracene/bisphenol A (An-BPA) and green-yellow emission (563nm) for anthracene/fluorinated bisphenol A. (An-BPAF) Organic diodes formed by sandwiching anthracene layers between indium–tin oxide (ITO) and aluminum contacts were characterized. The dc electrical properties of ITO/anthracene derivatives/Al diodes were studied using current–voltage measurements and showed ohmic behavior at low voltage. The conduction mechanism seems to be a space-charge-limited current with exponential trap distribution at high applied bias voltage. The ac electrical transport of the anthracene derivatives was studied as a function of frequency (100Hz–10MHz) and applied bias in impedance spectroscopy analyses. We interpreted Cole–Cole plots in terms of the equivalent circuit model as a single parallel resistance and a capacitance network in series with a relatively small resistance. The evolution of the electrical parameters deduced from fitting of the experimental data is discussed. The conduction mechanism revealed by I–V characteristics is in agreement with the impedance spectroscopy results.