Ultra-simple hybrid white organic light-emitting diodes with high efficiency and CRI trade-off: Fabrication and emission-mechanism analysis

摘要

We present a simple hybrid white organic light-emitting diodes (WOLED) consisting of only two layers, i.e., a hole-transporting layer and an emitting layer. The emitting layer is formed by simply co-doping a green phosphor and a red phosphor in bis[2-(2-hydroxy-phenyl)-pyridine]beryllium (Bepp_2), which acts as the blue emitter, electron-transport material, and high triplet energy host for the phosphors, i.e., a multifunctional chromo-phore. This simple device exhibits a maximum power and quantum efficiency of 46.8 lmW~(-1) and 16.5%, respectively, with a good CRI up to 90. The versatile experimental techniques are performed to gain a deep understanding of the emission mechanism. We believe that this simple design concept can provide a new avenue for achieving ultrahigh performance WOLEDs for lighting application.