Efficient, Single-Layer Organic Light-Emitting Devices

1. Efficient, Single-Layer Organic Light-Emitting Devices Timothy P. Lodge, University of Minnesota-Twin Cities, DMR 0819885 Principal Investigator Russell J. Holmes (IRG-2) Description and Significance Efficient OLEDs often require the use of an intricate device architecture. Graduate student Nicholas Erickson has instead taken an alternative approach, focusing on the use of a doped, graded emissive layer (G-EML) architecture that permits high efficiency in devices comprising only a single layer. Device composition varies continuously from nearly 100% hole-transporting material (HTM) at the anode to nearly 100% electron-transporting material (ETM) at the cathode, with an emitter uniformly doped throughout the structure. Erickson has demonstrated efficient, single-layer OLEDs emitting in the blue, green, and red. The tunable gradient allows for the optimization of electron-hole charge balance and low-voltage operation while preserving charge and exciton confinement. Gradient Cathode Anode =ETM =Phosphor =HTM Graded emissive layer (G-EML) OLED – The gradient provides charge and exciton confinement G-EML OLEDs based on blue, green and red phosphorescent emitters