Synthesis And Properties Of Novel Organic Light-emitting Materials Based On Carbazole And Pyrazole Derivatives

Since C.W.Tang and van Slyke demonstrated the first high-efficiency device,OLEDs have evolved from a scientific curiosity to a commercially viable technology incorporated into hand-held devices for bright,vibrant displays etc.OLED materials have drawn much attention all over the word.Two series of new OLED materials were designed and synthesized base on carbazole and pyrazole,respectively.The compounds obtained were characterized by ¹H NMR,¹³C NMR,FT-IR and elemental analysis.Then,the luminescence properties,thermal stability and electrochemical properties of the compounds were characterized by UV-vis absorption spectra,fluorescence spectra,DSC,and cyclic voltammetry measurements.Meanwhile,the relationship between the properties and structure of compounds has been studied as well.The main research work of this paper is as follows:1.3,6-dibromo-9-?2-bromobenzyl?-9H-carbazole and 3,6-dibromo-9-?4-bromobenzyl?-9H-carbazole were synthesized by using carbazole via bromination reaction.A series of new carbazole derivatives were synthesized by reacting with kinds of arylboronic acid.The characterizations of these compounds were carried out by means of FT-IR¹H NMR,¹³C NMR and elemental analysis methods.2.4-bromo-1-?4-bromophenyl?-1H-pyrazole and 4-bromo-1-?2-bromobenzyl?-1H-pyrazole were synthesized by using pyrazole via bromination reaction.A series of new pyrazole derivatives were synthesized by reacting with kinds of arylboronic acid.The characterizations of these Compounds were carried out by means of FT-IR,¹H NMR,¹³C NMR and elemental analysis methods.3.Twelve novel OLED materialsdesigned and synthesized successfully,these compounds have good thermal stability.The introduction of methylene leads to a great increase of the glass transition temperaturethe,ranged from 90.4 to 148.0?for carbazole derivatives,and pyrazole derivatives were83.0¹01.1oC.The E_HOMO and E_LUMO values of carbazole derivatives measured by cyclic voltammetry were-5.75^-5.37 eV and-2.05^-2.22 eV,respectively.The E_HOMO and _ELUMO values of pyrazole derivatives are-5.79^-5.55 eV and-2.06^-2.33 eV,respectively,indicating that these compounds have suitable energy level bandgap.4.The photophsical properties were analyzed.The maximum absorption wavelength of these Compounds was around 400-450 nm,these Compounds were typical blue light-emitting material.