Investigation Of The Organic Electroluminescent Materials Based On Novel Side-chain Polyfluorene

Organic electroluminescent diodes(OLEDs)have attracted a great deal of enthusiasm for research because of their great potential in lighting field.Improving the stability and efficiency of blue light is of great significance in the commercial application.In recent years,there is an attempt to attach the fluorescent groups to a non-emitting random coil polymer.For example,using polystyrene as the main chain,oligofluorenes as the pendants,the obtained polymers emit blue color.This molecule structure design concept showed us several advantages: The synthetic route would be simpler than that used for main-chain polymers;It becomes easier to get soluable mate-rials because the solubility is basically dominated by the nature of the backbone structure;The emission wavelength could be predetermined by pendant structure design;Crystallization of the chromophore(in comparison with small molecular weight sublimable systems)could be prevented;Polymerization of double bonds is one of the most mature technologies in the field of polymer science.The living polymerization method developed at present can easily obtain polymer with molecular weight control or ultrahigh molecular weight;Copolymerization with a wide variety of other vinyl monomers can achieve chemical modification easily.In this thesis,synthesized three kinds of target monomers and three kinds of sidechain polymers.The molecular weight,UV spectra,fluorescence spectra,1H-NMR and thermal stability of the polymer had been studied.The relationship between molecular structure and optical properties was also discussed.The main contents of the thesis were as follows.Firstly,it provided detailed introduction on the action mechanism,structures,perform-ance parameters of organic electroluminescent diodes and the research progress of the materials.Secondly,two vinyl fluorene derivatives named 9,9-dibutyl-2-vinylfluorene and 2-(2-ethinyl-9,9-dibutyl)-9,9-dibutyl-vinylfluorene,one carbazole-vinylfluorene named 2-carbazolyl-9,9-dibutyl vinylfluorene were synthesized.The structures of the monomers were characterized by 1HNMR.Thirdly,with 9,9-dibutyl-2-vinylfluorene,2-(2-ethinyl-9,9-dibutyl)-9,9-dibutylvinylfluorene and 2-carbazolyl-9,9-dibutyl vinylfluorine as monomers,three homopolymers of PBF ?PEBF and PCBF were synthesized.The polymers were proved to be macromolecules by measuring the molecular weight with GPC.Three polymers had very good thermal stability,5% weight loss temperature were 361 ?,412? and 398 ?,respectively.The relationship between molecular structures and optical performances of polymers in solution and film states was detected by ultraviolet and fluorescence technologies.The difference of the side chain groups had a great influence on the position of UV absorption peaks in the solution and film state.With the increasing of the conjugated length on the side chain groups,the UV absorption had a large red shift.A certain degree of red shift occurred on the fluorescence emission spectra with the increasing of conjugated length in the side chain,which was due to aggregation or excimers.The maximum emission peak position of PEBF was located at 450 nm,which had basically reached the level of blue light emission.