【作者】 王辰；

【导师】 印寿根； 杨利营；

【作者基本信息】 天津理工大学 ， 凝聚态物理， 2006， 硕士

【摘要】 有机电致发光器件作为一种新型的固体平板显示器件,有望能取代液晶显示器(LCD)而成为新一代的显示器件。理想的电致发光材料应该具有载流子注入和传输的平衡。通过改变和修饰有机半导体材料的化学结构可以调节材料的能带结构和载流子传输。吩噻嗪是一类富电子的杂环化合物。具有很强的荧光特性和结构调控性。吩噻嗪分子拥有一种非共平面构型,由于吩噻嗪分子的扭曲能够阻止π键堆积和链间激基复合物的形成,因而有可能提高EL材料的效率。近几年,吩噻嗪及其衍生物作为电致发光材料的研究才刚刚开始。本论文包括以下四个方面的内容:1.合成了三种吩噻嗪双醛单体M1,M2,M3。通过红外和核磁对其化学结构进行了表征,确认了其化学结构。研究了三种单体的紫外可见吸收光谱和荧光光谱。结果表明硫原子氧化为亚砜使得吩噻嗪与相邻苯环上的π-π*的共轭程度加强。硫原子进一步氧化为砜则在一定程度上破坏了芳环共轭性。2.以三种吩噻嗪双醛单体为基础,利用Wittig聚合法合成了三种含吩噻嗪及其衍生物单元的PPV型电致发光材料(P1,P2,P3)并通过核磁,红外等表征确认了其化学结构。研究了三种聚合物材料的紫外可见吸收(UV-vis)、光致发光(PL)、电致发光(EL)性能。制备了以这三种聚合物材料为发光层的单层器件和双层器件,获得了黄绿色发光。PL结果表明聚合物化学结构中由硫原子氧化为亚砜的化学结构的改变对薄膜态和溶液态的荧光发射有明显影响。而聚合物化学结构中硫原子的由亚砜到砜的氧化对其光致发光的影响不大。UV-vis结果表明吸电子基团S=O的引入使得聚合物的带隙增加。P2,P3单层器件的最大发光亮度分别为54.8cd/m2(4V)和32.56cd/m2(5V)。P1, P2, P3双层器件的最大发光亮度分别为277.6 cd/m2,400.7 cd/m2和796.3 cd/m2。3.采用Wittig聚合反应将吩噻嗪单元、吩噻嗪-5-亚砜单元引入聚芴骨架,合成了两种芴与吩噻嗪及吩噻嗪-5-亚砜的共聚物(P4,P5)。采用紫外可见光谱、荧光光谱、循环伏安法、光致发光(PL)、电致发光(EL)等手段研究了聚合物的光电性能。制备了结构为ITO/聚合物/Ca/Al的单层器件,获得了绿色发光。结果表明吩噻嗪单元的引入降低了聚芴的电离势(IP),提高了电子亲和势(EA),改善了材料的载流子传输能力。循环伏安结果表明S=O基团的引入没有明显增加材料的电子亲和势。P4,P5单层器件的最大亮度分别为20 cd/m2(16 V)和12.5 cd/m2(15 V)。4.采用Wittig聚合反应将吩噻嗪单元引入聚噻吩骨架,合成了噻吩与吩噻嗪共聚物(P6)。采用紫外可见光谱、荧光光谱、循环伏安法、光致发光(PL)、电致发光(EL)等手段研究了聚合物的光电性能。制备了单层器件获得了橙色发光。相比均聚吩噻嗪而言,噻吩基团的引入大大提高了聚合物材料的LUMO能级,却对其HOMO能级影响很小。单层器件的最大亮度为50 cd/m2(17V)。更多还原

【Abstract】 Polymer light emitting devices have been a fascinating subject owing to its potential application in large-scale flat displays. In order to have better performance, it is essential to develop novel structural polymeric materials with balanced transport of both injected electrons and holes. By changing or modifying the structures of organic semiconductor materials can easily adjust the energy level and charge transporation. Phenothiazine is a well -known heterocyclic compound with electron-rich nitrogen and sulfur heteroatoms.Conjugated polymers and copolymers based on phenothiazine have been investigated. It has been demonstrated that phenothiazine unit is an excellent p-type building block for lowering ionic potential of conjugated polymers due to its readily injection and transport of hole and non-planarity of phenothiazine impedesπ-stacking aggregation and intermolecular excimer formation which maybe lead to the poor quantum efficiency.Three novel phenothiazine-based monomers (M1,M2,M3) were designed and synthesized.Their physical and chemical properties were characterized by UV-vis and PL The results reveal that conversion of electron-donating sulfur in phenothiazine molecular to electron-withdrawing phenothiazine-5-oxide can enforce theπ-π* transition.However, the conversion of phenothiazine-5-oxide in phenothiazine molecule to phenothiazine destroy theπ-π* transition.Three polymers containing phenothiazine, phenothiazine-5-oxide and phenothiazine -5,5-oxide units were prepared by Wittig reaction. The photo-physical and electroluminescent properties of resulting polymers were investigated.Single layer device with a structure of ITO/ polymer /Ca/Al and double layer devices with a structure of ITO/polymer/Zn(BTZ)2/Ca/Al were built up. The brightness of double layer devices for P1,P2 and P3 is 277.6 cd/m2, 400.7 cd/m2 and 796.3 cd/m2, respectively.Two novel copolymers composed of fluorene and phenothiazine derivates are synthesized.The photo-physical, electroluminescent and electrochemical properties of two polymers were characterized by UV-Vis, PL, EL and Cyclic Voltammetry (CV). Single layer structure devices with the configuration of ITO/Polymers/Ca/Al were fabricated. The CV results demonstrated that introduction of phenothiazine moiety into polyfluorenes can enhance electron affinity (EA) and lower the ionic potential (Ip). EL results revealed that all these two copolymers emit green light with the maximum brightness of 20 cd/m2(16 V)and 12.5 cd/m~2(15 V),respectively.Copolymers of thiophene-co-phenothiazine were prepared by Wittig reaction. The synthesis, photo-physical and electroluminescent properties of the resulting polymers were analyzed by FT-IR, GPC, 1H-NMR, UV-Vis, Photoluminescence (PL), Electroluminescence (EL) and Cyclic Voltammetry (CV). The single layer devices with configuration of ITO/polymers/Ca/Al were studied. The device with a single layer structure of ITO/Polymer/Ca/Al emit red light with the maximum brightness of 50 cd/m2(17V).更多还原