Synthesis And Properties Of Conjugated And Non-conjugated Polymers Based On Benzimidazole Iridium Complexes

In recent years,Organic Light-Emitting Diodes(OLEDs)have become a main tendency in the future development of display technology due to its features of self-illumination,high luminescence efficiency,low energy consumption and flexible display.Nowadays,small-molecule organic and polymer materials are widely used in OLEDs devices.Generally,small-molecule material devices are made by vacuum vapor deposition process,but there are shortcomings such as high production cost,serious material waste and low yield,etc.PLEDs can be prepared by solution spin coating and ink-jet printing and other solution processing technologies,which have the advantages of low-cost and simple production process,thus they are more suitable for large-scale production.This paper is mainly divided into the following areas:1.In the first chapter,orange-red iridium complexes were designed and synthesized with 2-(4-bromophenyl)-1-H-benzimidazole as the main ligand and 2-naphthalenyl-1H-benzimidazole as the secondary ligand,which were suspended on polyfluorene(PFO)main chains by Suzuki polycondensation reaction to obtain a series of thermally stable main-chain-type conjugated phosphorescent polymer materials.2.In the second chapter,the green-phosphorescent iridium complexes were designed to be synthesized with 2-phenyl-1H-benzimidazole as the main ligand and 4-vinyl benzoic acid as the secondary ligand,and they were ligated onto the side chains of polyvinyl carbazole(PVK)as the backbone by free radical polymerization to obtain non-conjugated polymer materials in different ratios.Based on this,the vinyl POSS with a cage-frame structure was introduced to obtain a phosphorescent polymer material with good thermal stability and high fluorescence quantum yield.3.In the third chapter,electroluminescent devices with the structure of ITO/PEDOT:PSS(30 nm)/polymers(40 nm)/TPBI(37 nm)/Al(80 nm)were made with the phosphorescent polymer materials synthesized in Chapters I and II as luminescent layers,respectively.The devices of conjugated polymers PFO(Ph BI)₂Ir(2-Na BI)-1.0 was able to achieve white light emission with maximum current efficiencies of 3.41 cd/A a with color coordinates at(0.32,0.34).The non-conjugated copolymer PH2 device has a maximum brightness of 2488 cd/m2,a maximum current efficiency of 9.83 cd/A,a maximum power efficiency of 3.08 lm/W,and a maximum external quantum efficiency(EQE)of3.65%.After the introduction of POSS,the copolymer PH5 device increased to a maximum brightness of 4391 cd/m2,a maximum current efficiency of 19.3 cd/A,a maximum power efficiency of 6.05 lm/W,and a maximum external quantum efficiency of 7.06%.The experimental data showed that the electroluminescent electrical properties of the polymers were significantly improved after the addition of POSS.