Nitrogen-modified a-C:H layers applied for light emitting diodes

Abstract

The main problem of organic light-emitting diodes (OLEDs) is their degradation caused by the interaction of the polymer with atmospheric factors. The development of new encapsulation methods and materials for OLEDs can solve this problem. In this work prompted us to investigate the possibility of using hydrogenated amorphous carbon nitrogen-modified (a-C:N:H) layer as protective passive coatings. The layers were deposited on the active polymer layer and as a stand-alone active layer in the devices by radio frequency plasma assisted chemical vapor deposition (13.56 MHz). Different types of the diodes architectures (glass/ITO/PVK/Ca/Al, diodes with glass/ITO/PVK/a-C:N:H/Ca/Al and glass/ITO/a-C:N:H/Ca/Al) were prepared for which specified of the current-voltage and electroluminescent-voltage characteristics. The layers structure and morphology were assessed by X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX). The UV Vis spectroscopy studies have been carried out for the a-C:N:H layer and absorption bands were determined. The photoluminescence and fluorescence of the layers were confirmed. The optical properties and chemical stability were measured by spectroscopic ellipsometry. The influence of solvents on the dispersion dependence of the refractive index and extinction coefficient was also determined. The obtained results are promising in the context of the layers applications in OLEDs technology.