Hybrid Blue Organic Light Emitting Diodes with Fluorescent and Phosphorescent Emitters Along with an Interlayer

In this study, we report hybrid blue organic light emitting diodes (OLEDs) with triple emitting layers (EMLs) composed of fluorescent and phosphorescent emitters along with interlayers. The electrical and optical properties of hybrid blue OLEDs are investigated as a function of the various combinations of EML configurations. In addition, the electroluminescent (EL) spectra of the devices are resolved into their base components to understand the origin of blue emission by electronic transitions of excitons. It was observed that the current density and the position of the recombination zone are dependent on the configuration of the p and n-type host materials due to the fact that the properties of the host materials affect electron and hole mobility. Also, the phosphorescent dominant emission triggers drastic roll off in efficiency, which was reduced when the fluorescent emitter is involved with the emission. Adding an interlayer between the fluorescent and phosphorescent EMLs prevented triplet exciton quenching and improved overall efficiency.