Blue electroluminescent devices based on polymer -Structure design

摘要

Since Burroughes et al. and Braun et al. reported the electroluminescence (EL) from poly(p-phenylene vinylene) (PPV) device, polymer materials have been used as the emitting layer of EL device with 4% quantum efficiency, and a few studies on conjugated polymer diodes emitting blue light have been reported. Because of having wider band gaps, the organic polymer is easier to realize the blue emission than Inorganic semiconductors. Generally, the conductive conjugated polymers with high fluorescence areused for EL device. We modified the device characteristics by two approaches: one is the internal factor design-an incompletely conjugated chemical structure of emitting materials is used to produce high efficiency radiative recombination of exciton; the other is the external factor design-the heterojunction and the multilayers quantum wells (MQWs) provide a better confinement for injected carriers and enhance the transition probability so as to produce radiation photons as more as possible.