Efficiency and stability of polymer light-emitting diodes

The operation characteristics of polymer light-emitting diodes (PLEDs) are strongly dependent on materials, processing and the structure of the device . The device structure developed at Philips Research is presented together with some typical results for brightness, efficiency, response times and st ability. The PLEDs typically operate at a voltage of 3-4 V for a brightness of 100 cd m(-2) and have an efficiency ranging from 2 cd A(-1) for orange emitting polymers (610 nm) up to 16 cd A(-1) for green emitting polymers (5 50 nm). The response time under conditions for display operation is determi ned by the charge carrier transport properties and amounts to 43 ns. Lifeti mes of several thousand hours have been obtained for large orange emitting devices of 8 cm(2) for daylight visibility at room temperature.