Optoelectronic behaviour of zinc phthalocyanines doped with anthraquinone derivatives and their potential use in flexible devices

Zinc phthalocyanine (ZnPc) was doped with 1,4-diaminoanthraquinone, anthraflavic acid and 2-ethylanthraquinone. The organic semiconductors obtained were used in the manufacture of thin films, which were characterized. Films were used to prepare (PET/ITO/doped ZnPc/Ag) flexible devices, whose electric conductivity was evaluated as a function of temperature; some of the devices show a considerable increase in their activity up to values of around 2 × 10⁻¹¹ S^/cm to 10 × 10⁻¹¹ S/cm and 3 × 10⁻¹¹ S/cm to 8 × 10⁻¹¹ S/cm for 0.5 and 1.0 V, respectively. Absorbance, Q-band, B-band and optical activation energy were also evaluated by ultraviolet-visible spectroscopy. Optical bandgap E_g^opt values calculated for the semiconductors have a value of around 1.35 eV. The semiconductor devices were annealed in accelerated time and temperature conditions and their optical activation energy was later re-evaluated. The films exhibit two transitions; the first transition corresponds to the optical bandgap, E_g^opt, and the second one to the fundamental gap, E_g.