Solution Processed Small Molecule-Based Green Phosphorescent Organic Light-Emitting Diodes Using Polymer Binder

Abstract

The authors have demonstrated efficient green organic light-emitting diodes (OLEDs) by using polymer binder. We fabricated small molecular green OLEDs and mixed polymer as a binder such as polystyrene (PS) or poly(N-vinylcarbazole) (PVK). The 4,4'-N,N'-dicarbazole-biphenyl (CBP) is a small molecular material with excellent electrical properties however it become crystalline at high temperature. Polymer binder prevents crystallization of CBP and lead to high efficiency. Therefore, we added PS or PVK into CBP as a polymer binder. As a result, we obtained maximum luminous efficiency, power efficiency and quantum efficiency of 22.8 cd/A, 11.6 lm/W and 6.61% at 23% PS added device.