基于1-(4-己氧)苯和2,4,6-三苯基-1,3,5-三嗪功能化芴单元的聚合物蓝光材料的合成与表征

Synthesis and Characterization of Blue Light Emitting Polymer Based on 2,4,6-Triphenyl-1,3,5-triazine and 1-(4-Hexyloxy)-benzene Functionalized Fluorene Units

以聚(9,9-二己烷芴)(1)和聚(9,9-二(1-(4-己氧)苯)芴)(2)作为参照物,通过Suzuki偶联反应合成了侧链9位碳含有4-己氧基苯和2,4,6-三苯基-1,3,5-三嗪单元的芴共聚物3.聚合物1,2和3固体粉末的5%质量热损失温度分别是274,318和401℃,玻璃化转变温度分别是91,120和139℃.聚合物1,2和3在甲苯溶液中的最大吸收峰和荧光发射峰分别在380和435 nm.从聚合物1到聚合物3,薄膜的荧光发射最大半峰宽逐渐降低.大体积刚性吸电子2,4,6-三苯基-1,3,5-三嗪基团的引入,使聚合物1,2和3的热稳定性、蓝光发射的色纯度和光谱稳定性逐渐提高,不同工作电压驱动下聚合物3稳定的电致发光光谱进一步证明了这一点.聚合物1,2和3的最高占有轨道能级分别为-5.72,-5.95和-5.96eV,最低未占有轨道能级分别为-2.70,-2.39和-2.43 eV.聚合物1,2和3的三线态能级分别为2.82,2.81和2.97 eV.聚合物1,2和3的单线态-三线态能级差分别是0.32,0.32和0.15 eV.4-己氧基苯的引入使聚合物的能隙变宽,而吸电子的2,4,6-三苯基-1,3,5-三嗪的引入使聚合物单线态-三线态能级差依次减少.聚合物1,2和3粉末均易于形成非晶薄膜.聚合物3粉末的有序性介于聚合物1和2之间,聚合物2侧链的烷氧基苯有助于提高固体粉末有序形态的多样化.综合结果表明,侧链含有刚性4-己氧基苯和2,4,6-三苯基-1,3,5-三嗪基团的无规共聚物3具有更佳的综合光电性质.

Polymer 3 based on 1-(4-hexyloxy)-benzene and 2,4,6-triphenyl-1,3,5-triazine functionalized fluorene units was synthesized and characterized,whose optoelectronic properties were further compared with those of poly(9,9-dihexyl-fluorene)(1)and poly(9,9-di(1-(4-hexyloxy)-phenyl)-fluorene)(2).The 5%weight loss temperatures of polymers 1,2 and 3 thin solid powders are 274,318 and 401℃,and their glass transition temperatures in the same state are 91,120 and 139℃,respectively.The maximum absorption and photoluminescent emission peaks of polymers 1,2 and 3 in toluene solution are 380 and 435 nm,and their optical band gaps in toluene solution are 2.95,2.95 and 2.91 eV.The triplet energy levels of polymers 1,2 and 3 are 2.82,2.81 and 2.97 eV,while their singlet energy levels are 3.14,3.13 and 3」2 eV,which makes the singlet-triplet energy splitting gaps fbr polymers 1,2 and 3 to be 0.32,0.32 and 0.15 eV.The highest occupied molecular orbital energy levels of polymers 1,2 and 3 are-5.72,-5.95 and-5.96 eV and the lowest unoccupied molecular orbital energy levels are-2.70,-2.39 and-2.34 eV.The introduction of 4-hexoxybenzene widened the energy band gaps of the polymers,while the electron deficient 2,4,6-triphenyl-1,3,5-triazine made the single-triplet energy splitting gaps of the polymers successively decreased,but it did not endow polymer 3 with thermally activated delayed fluorescence characteristic.With the introduction of rigid and electron deficient 2,4,6triphenyl-1,3,5-triazine into the 9-carbon of the fluorene units in the polymer,the thermal stability,color purity and photostability of blue light emitting solid were improved in the turn of polymers 1,2 and 3,which were further validated by the stable electroluminescent spectra of polymer 3.The wide-angle X-ray diffraction results of the polymers 1,2 and 3 powders show that all polymers have excellent amorphous properties in nature.The phase diversity of polymer 3 powder locates between those of polymers 1 and 2,and the alkoxyl phenyl substituted group on the polymer 2 side chain is helpful to improve the diversity of ordered morphology in solid powder.The random copolymer 3 exhibits much better photoelectric properties than those of polymers 1 and 2.