A study of the electroluminescence mechanism in a light-emitting composite produced with PEDOT:PSS, PVA and Zn_2SiO_4:Mn

摘要

Light-emitting composites are materials that combine the light-emitting characteristic of phosphor materials with the solubility of conductive polymers. This paper has the purpose of showing an experimental study on electroluminescence in a light-emitting composite comprising PEDOT:PSS as the conductive polymer and Zn2SiO4:Mn as the phosphor material. The relationship between d.c. current and voltage, as well as luminance and voltage, of light-emitting devices were measured for different active layer thickness and different temperature conditions. Luminance was also measured during impedance spectroscopy experiments (a.c. characterization). It was observed that the electroluminescence in the studied light-emitting composite is a field effect mechanism, with turn-on electric field of (4.6 +/- 0.2) kV/cm, and that the electroluminescence efficiency is independent of temperature. Additionally, it was observed that electroluminescence is strictly dependent on the drift current of charge carriers. Finally, a model was proposed to describe the electrical properties and luminance of the studied light-emitting composite.