Synthesis Of Novel Side Chain Polyfluorenes And Their Photoelectric Properties

Organic electroluminescent diodes(OLEDs)have attracted the enthusiasm of a large number of scholars because of their great prospects in the field of lighting.Improving the stability of blue materials and luminous efficiency for the realization of OLED in the commercial application is of great significance.In recent years,attempts have been made to connect fluorophores to nonconjugated random coil polymers,for example,blue-light emitting polymers with polystyrene as the main chain and side chain suspended low fluorene groups.This molecular structure design concept has the following advantages: Compared with the main chain conjugated polymer synthesis path is relatively simple;the solubility of the material determined by the flexible core of the polymer,to avoid the many main chain conjugated polymer dissolved The wavelength of the emitted light is determined by the low molecular weight fluorophore of the side chain,which is easy to be regulated in the synthesis.When grafting to the polymer chain,the problem of the crystallization of the small molecule fluorescent material is expected to be solved,which is one of the most mature technologies in the field of polymers.The active polymerizatin method developed at present can easily obtain polymers with molecular weight controllable or ultra high molecular weight,and copolymerized with a variety of other vinyl monomers to realize chemical modification.In this paper,we synthesized trifluorene ethylene derivatives and two carbazolylsubstituted fluorene derivatives.All compands have been cheeked by UV spectra,fluorescence spectra,nuclear magnetic resonance spectra and thermal stability.The relationship between molecular structure and photoelectric properties have been discussed,hoping to explore the performance of more excellent blue electroluminescent material.The main contents are as follows:The mechanism,structure and research progress of organic electroluminescent diodes are introduced in detail.Synthesis of a tri-polyfluorene ethylene derivative: 2-(2-ethynyl-7-(2-ethynyl-9,9-dibutylfluorene)-9,9-dibutylfluorene),9-dibutyl fluorene ethylene,two carbazole-fluorenederivatives: 2,7-dicarbazolyl-9,9-dibutyl fluorene;2-(2-ethynyl-7-carbazolyl-9,9-dibutylfluorene)-9,9-dibutyl fluorene ethylene.And its structure was determined by1 HNMR.The results were consistent with the target products.Three fluorene ethylene derivatives have very good thermal stability,5% heat loss temperature of 430 ?,410 ?,420 ?.The relationship between the molecular structure and the optical properties of the solution and the fluorene ethylene derivatives was investigated by UV and fluorescence techniques.It was found that the different positions of the substituents could produce UV absorption at the solution and film.The fluorescence absorption spectra of the substituted groups were increased with the increasing of the conjugated length of the substituents,and the fluorescence emission spectra shifted to some extent with the increase of the conjugated volume of the substituents.The carbazolesubstituted fluorene ethylene derivatives have absorption and emission wavelength between the dimer and the trimeric homopolymer.based on it an OLED luminescent materials covering the full spectra can be expected.