Light-emitting Diodes Based On New Blue Electroluminescent/Host Polymer

Polymer light-emitting diode (PLED) can be prepared by spin coating, printing, ink jetprinting, whose manufacturing cost can be very low. Thus, the PLED has a great applicationpotential for flat panel display (FPD) and solid-state lighting (SSL)(including generallighting purposes and backlight of liquid crystal display). Red, green and blue color areessential to achieve full color display. Compared to the more mature red and green devices,blue device needs to further improve its performance, including device life, efficiency,stability and so on. This paper provide two different methods to achieve high-efficiency andstable blue PLEDs by studying the charge carrier injection and transport and different devicestructures.Phosphor doped PLED has been widely studied since it can achieve100%internalquantum efficiency. In the third chapter, the efficient device performance has been achieveddue to the use of host material PICzFB containing carbazole unit and tetrafluorobenzene unit.PICzFB has good theraml stability with a glass transition temperature of200℃and thermaldecomposition temperature of455℃. The band gap of PICzFB is3.32eV and the tripletenergy level is2.73eV, suitable as the blue host material. An efficient blue phosphorescentdevice employing the new host material via a solution process has been realized with themaximum current efficiency of5.0cd/A, maximum brightness of1094cd/m2when dopedblue-emitter FIrpic. For the device when doped green-emitter Ir(mppy)3maximum currentefficiency of27.6cd/A, maximum brightness of3916cd/m2can be realized.In order to improve the stability of the device, it is suggested that avoiding using acidichole injection material PEDOT:PSS and low work function cathode material should beavoided. In the fourth chapter, inverted PLED using solution-processed ZnO film with aconfiguration of ITO/ZnO/PFN-SO/Polymer/MoO3/Al were fabricated. By using the PFN-SOas a surface modifier layer, the maximum current efficiency of1.32cd/A, brightness of2428cd/m2were realized. Although the maximum efficiency of the inverted PLEDs is less than theconventional PLEDs, it provides an idea of prepartion for the stable performance of thedevice. Thereafter, we expect that, excellent performance of blue devices can be fabricated by choosing right blue materials and interface materials.