ABSTRACT
Since the first report of polymer light-emitting diodes (PLEDs) by Burroughes et al. in 1990 [1], rapid progress has been made in improving device brightness, efficiency, and operational lifetime [2-7]. These developments have brought PLEDs to the stage where they are ready for commercialization [4]. To date, poly(/?-phenylenevinylene) (PPV) and its derivatives are by far the most popular light-emitting layers used in PLEDs and perform very well [5]. Recently, the highest luminescence efficiency (22 Im/W) in PLEDs has been achieved in devices using yet another kind of polymer-fluorene-based polyer-as the active light-emitting layer [5,6]. Fluorene-based polymers, such as poly(9,9-dioctylfluorene) (PFO), are now attracting much interest because the PFO-based PLEDs have low turn-on voltage, high brightness, and high efficiency [6-12].
