STABILITY OF POLYMER LEDS

Polymer LEDs have a number of attractive properties that make them sui table for many applications. Operating at low voltage, bright large-ar ea devices can be made by simple technology. One of the limitations th at prohibited industrialization of polymer LEDs was their limited life time. An overview of the improvement of polymer LED performance at Phi lips is presented. The progress during the last year is reflected by l ifetimes of many thousands of hours for 8 cm(2) devices that operate a t daylight visibility under ambient conditions. Diagnostic measurement s have been performed on polymer LEDs before and after stress testing, and on the materials used in these devices. These measurements have c ontributed to the understanding of the nature of the degradation of po lymer LEDs. (C) 1998 Elsevier Science B.V.