【作者】 任辉彩；

【导师】 高占先； 刘迪；

【作者基本信息】 大连理工大学 ， 有机化学， 2012， 博士

【摘要】 有机电致发光材料及器件由于在平板显示和白光照明等领域表现出广阔的应用前景,已经成为当前科学界和产业界的研究热点之一。红色发光材料是实现全色显示和白光照明必不可少的三基色(红、绿、蓝)材料之一,也是有机电致发光材料研究中比较薄弱的,因此开发新型、高效的红光材料,进一步提高其发光亮度和效率,具有重要的现实意义。基于此,本论文设计、合成了一系列红色有机荧光和磷光材料,并系统地研究了它们的电致发光性质。首先,设计、合成出溶解性好、具有区域隔离效应的主体型可旋涂红色发光材料是避免红光材料的浓度淬灭和降低器件生产成本的有效途径之一。而高度有序、均三维结构的树枝状大分子恰好能满足这一需求。因此,我们以高效的红色发光体苝酰亚胺为发光核,通过Diels-Alder加成反应,在花环的1,6,7,12-位以发散式途径引入外围含有全氟苯、氰基、3,6-二叔丁基咔唑以及N-苯基-1-萘胺等功能基团的聚苯树枝,成功地合成了一系列苝酰亚胺类树枝状红色荧光材料。所得化合物的最大分子量超过一万,在普通的有机溶剂中都具有较好的溶解性,可通过湿法(如旋转涂膜的方法)制备器件。它们在薄膜中的吸收和发射光谱与溶液中的光谱相比,均发生了较微弱的蓝移,说明外围的多苯类树枝起到了很好的区域隔离作用,可以有效地防止荧光的浓度淬灭。实验表明,这类化合物在溶液中具有很强的红色发光性能,荧光量子效率高达95%。利用循环伏安法研究了它们的电化学性质,化合物均出现了两对可逆的还原峰,说明其具有很好的电子传输性能；表面基团为咔唑的树枝状分子同时出现了一对可逆的氧化峰,表明这类化合物兼有空穴传输的功能。热重分析实验表明,这些材料的分解温度达400℃以上,表现了优异的热稳定性。以这些树枝状分子为发光层通过旋涂法制备了非掺杂的有机电致发光器件,电致发光发射峰位于橙红光区域。其中基于Gl-Cz的器件性能最好,最大亮度为220.7cd m-2,电流效率最高为0.22cd A-1。这也是花酰亚胺类红色发光材料中较好的器件数据。其次,针对电致磷光材料相比电致荧光材料具有突出的效率优势和开发高效率红光材料的必然趋势,以及2-苯基苯并噻唑铱配合物这类橙黄色磷光材料发光性能优良,但却种类有限、发光颜色单一,我们在苯并噻唑的2-位分别引入氧芴、硫芴、二氧化硫芴和二苯磷酰基苯基等大芳基基团形成四种新结构的2-芳基苯并噻唑配体骨架,并制备其双环金属铱配合物。与2-苯基苯并噻唑铱配合物相比,这一系列铱配合物发光都出现了红移,其室温磷光覆盖了从黄光到橙红光的较宽范围,其固体薄膜状态下的磷光发射峰集中在590-610nm之间,并且随芳基吸电子能力增强,磷光发射逐渐红移。以这些配合物为发光客体,利用真空蒸镀和溶液旋涂技术制备了掺杂型电致发光器件,获得了较好的器件性能,其中,含有硫芴基团的铱配合物的橙光器件最大亮度达到55530cd m-2,最高电流效率为54cd A-1,这是迄今所报道的橙光器件的较高效率之一。表明这是一系列具有较大应用前景的黄色到橙红色磷光材料。更多还原

【Abstract】 Organic light-emitting diodes (OLEDs) have been one of the research focuses in science and industry due to their great application prospects in flat-panel displays and white-light lighting. As one of the primary colors (red, green and blue), the red emitters are required for full-color applications and white-light lighting. However, they are scarce with low efficiency among emitting materials. It is essential to develop new red emitters and improve the luminance and efficiency. In this dissertation, a series of red fluorescent and phosphorescent materials were designed and synthesized. The electroluminescent properties of these materials were studied.First, an effective way to solve the fluorescent quenching effect and reduce the cost of device production is to design and synthesize red host emttiers that are capable of being made non-doped OLEDs by solution-processing methods. Dendrimers with well-defind three dimensional dendritic structures are perfectly able to be served for this demand. Therefore, a series of red light-emitting dendrimers up to second generation based on a perylenediimide (PBI) core and polyphenylene dendron with pentafluorophenyl, cyano, carbazole and N-phenyl-1-naphthalenamine surface groups, were prepared via Diels-Alder cycloaddition. The second generation dendrimers were obtained by the traditional divergent way. The maximum molecular weight of these dendrimers approached ten thousands. And they show good solubility in common organic solvents so that it is possible to fabricate devices by solution methods such as spin-coating. The hypsochromic effect was observed for these dendrimers in both absorption and fluorescence spectra of the solid film compared with their solution. This implies the excellent site-isolation effect of the bulky dendrons and surface groups on the PBI emissive core. These dendrimers show strong red fluorescence in solution and the highest quantum yield is95%. The cyclic voltammty measurements were performed to investigate the redox properties of these compounds. Two reversible reduction waves were observed for all of them, indicating that they possessed good electron transport properties. And the dendrimers with carbazole surface groups show an additional oxidation peak, demonstrating the hole transport nature of them. All the dendrimers start to decompose at a high temperature up to400℃, indicating the excellent thermal stability. They were used as non-doped emitting layer to fabricate OLEDs by spin-coating method. The EL spectra are located at orange-red region. The OLED based on Gl-Cz has the highest luminance and current efficiency as220.7cd m-2and0.22cd A-1, respectively. This is the better data among the devices based on PBIs materials.Second, in order to increase the emission efficiency, novel phosphorescent iridium complexes were developed for use in red OLEDs, since electrophosphorescent materials are advantageous over fluorescent materials in much higher device efficiency. The Ir(Ⅲ) complexes containing2-phenylbenzothiazole and its derivatives as major cyclometalating ligands are typical yellow/orange phosphorescent materials, which are widely used in both single color and white OLEDs. These iridium complexes have merits such as high phosphorescent quantum yields and easy synthesis in comparison with other analogues. However, the few derivatives are only those with simple substituents on the2-phenylbenzothiazole ligands, the emitting color of whom are also limited in yellow or orange range. In order to develop novel phosphorescent materials with excellent performance and various emitting colors, four2-arylbenzothiazole ligands frameworks were designed and synthesized by introducing dibenzofuran, dibenzothiophene, dibenzothiophene-5,5-dioxide, or dipenylphosphine oxide into the2-position of benzothiazole moiety. Their biscyclometalated iridium (Ⅲ) complexes with acetylacetone (acac) as ancillary ligand were then prepared. These complexes emit orange-red phosphorescence at room temperatures in solid films with emission peaks at590nm to610nm. And the phosphorescence shows red-shift trend with increasing electron-withdrawing ability of the aryl part. The high performance phosphorescent OLEDs were fabricated using these complexes as doped emitters. One of these OLEDs exhibited a maximum luminance of55530cd m-2and the highest efficiency of54cd A-1, which are among the best results reported for orange OLEDs so far. All the data indicate that these Ir(Ⅲ) complexes are promising yellow to orange-red organic phosphorescent materials.更多还原