Synthesis And Properties Of Side Chain Blue Phosphorescent Polymer Host Materials Containing Phenylcarbazole And Triphenylphosphine Oxygen

Organic light-emitting diodes(OLEDs)have been the most promising display devices in the 21 st century because of their superior advantages in the field of flat panel display.Phosphorescent light-emitting diodes(PhOLEDs)are also the focus of current research due to the theoretical internal quantum efficiency of 100%.The luminescent layer of PhOLEDs is usually designed with a host/guest system to minimize energy loss and improve efficiency.Among them,the blue PhOLEDs require the hosts with high triplet energy level and balanced charge transport ability,which is difficult to develop.Compared with small molecules,the film-forming ability of polymers is better,so it is suitable for solution processing by spin coating.Therefore,designing and synthesizing a suitable blue bipolar phosphorescent polymer host is vital.In this thesis,phenyl carbazole and triphenylphosphine oxide are used as the hole transport and the electron transport unit,respectively.Two kinds of bipolar polymers with carbon and siloxane main chains are designed and synthesized.Five carbon chain polymers have high triplet energy levels(?3.0 eV),and they are used as light-emitting layers by doping FIrpic to prepare blue PhOLEDs.The polymer P(VPK7VDPO3)with tphenyloxazole and triphenylphosphine oxide(7:3)displays the most balanced charge transporting ability due to the addition of a small amount of triphenylphosphine oxide.And thus the performance of PhOLEDs is the best among them.The device has a maximum current efficiency(?c,max)of 9.1 cd/A,a maximum power efficiency(?p,max)of 3.2 lm/W,and a maximum external quantum efficiency(?ext,max)of 4.9%.Based on this result,polysiloxane(PCz7PO3Si)with the same ratio of phenyloxazole and triphenylphosphine oxide(7:3)is also synthesized.The experimental results indicate that PCz7PO3Si possesses good thermal stability,excellent film-forming ability,high triplet energy level(3.0 eV),relatively balanced hole mobility(1.15×10-3 cm2 V-1 s-1)and electron mobility(5.75×10 4 cm2 V-1 s-1),which promises its potential application in manufacturing highly efficient blue PhOLEDs.