29.1: Invited Paper: Recent Progress in Light-Emitting Polymers for Full Color OLEDs

We have significantly improved the efficiency, lifetime and hue of red, green, blue (RGB) light-emitting polymers (LEPs) through intensive studies on degradation and charge balance in polymer organic light-emitting diodes (OLEDs). The degradation of LEPs during device operation is shown to result from decreased emissive material fluorescence efficiency and a loss of charge-carrier balance. Laser photolysis results show that low-energy sites are generated in the LEP during driving, leading to the quenching of blue and green emission, but not red emission. Charge carrier balance also shifts due to decreased electron injection compared with hole injection. Taking these degradation mechanisms, we have focused on copolymerization of various functional units to stabilize the photoluminescence (PL) intensity, and the balance of charge carriers. In this paper, we present the degradation mechanism and performance of our latest RGB LEPs.