Improved performance and stability of organic light-emitting devices with silicon oxy-nitride buffer layer

Abstract

The use of silicon oxy-nitride ( SiO x N y ) as an anodebuffer layer in organic light-emitting devices(OLEDs) with a configuration of indiumtin oxide ( ITO )/ SiO x N y /α -naphtylphenyliphenyl diamine (NPB)/8-hydroxyquinoline aluminum/Mg:Ag has been studied. With a SiO x N y buffer layer several angstroms thick, the device efficiency increased from 3.0 to 3.8 cd/A. The buffer layer also protected the ITO surface from contamination due to air exposure. Upon exposing the cleaned ITO substrate to air for one day before device fabrication, the device current efficiency and turn-on voltage degraded to 2.1 cd/A and 4.3 V, respectively, from 3 cd/A and 3.3 V for the device fabricated on an as-cleaned ITO surface. In contrast, devices prepared on air-exposed SiO x N y / ITO surface had almost the same current efficiency (3.85 cd/A) and turn on voltage (3.7 V) comparing to devices (3.8 cd/A and 3.7 V) fabricated on freshly prepared SiO x N y / ITO surface. The results suggested that SiO x N y is a promising anodebuffer layer for OLEDs, for both efficiency and stability enhancements.