Quinoline-Modified Phenanthroline Electron-Transporters as n-Type Exciplex Partners for Highly Efficient and Stable Deep-Red OLEDs

Abstract

Abstract Although stable deep-red organic light-emitting devices (OLEDs) exhibit potential applications as unique illumination light sources for plant growth and in health monitoring systems, their electron-to-photon conversion efficiency, represented by the external quantum efficiency (EQE), is significantly lower than that of the other primary colors. Thus, to overcome this limitation, n-type exciplex host partners based on quinoline-modified phenanthroline derivatives, X-BPhen, were designed and synthesized in this study. These X-BPhen derivatives formed exciplexes on combination with a p-type host material, NPD, behaving as host materials in deep-red phosphorescent OLEDs. The corresponding devices exhibited a maximum EQE of 17.6%, with CIE coordinates of (0.71, 0.29), and an LT80 of 410 h at a constant current density of 25 mA/cm2; this is among the best performances reported for stable deep-red OLEDs.