Abstract
We propose an emitting assist (EA) dopant system for obtaining organic light-emitting diodes with pure red emission. The EA dopant (rubrene) did not itself emit but assisted the energy transfer from the host (Alq_3) to the red emitting dopant (DCM2). The cell structure used was [indium-tin oxide (ITO)/hole injection layer (20nm, CuPc)/hole transport layer (50nm, NPB)/emitting layer (40nm, Alq_3 + DCM2 (2wt%) + rubrene (5wt%))/MgIn]. A pure red emission (CIE:x=0.64, y=0.36) was obtained in this cell within the luminance range of 100 - 4000 cd/m^2. On the other hand, when the cell was not doped with rubrene, the emission color changed from red to orange as the luminance increased. The EA dopant system is a promising method for obtaining red OLEDs.
