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71.
Chang Yuwei Yang Jingjun 《中国稀土学报(英文版)》2006,24(2):181-181
A ligand, N^1, N^4-di （ pyridin-2-yl ） succi- namide （L） and its lanthanide（ IH ） complexes （RE = La, Eu, Tb, Gd, Yb ） were synthesized and characterized in detail. The results indicate that the composition of the binary complexes is determined as [ REL （H2O）2（NO3）2] NO3, that the complexes are 1 ： 1 electrolytes in DMF, and that the Tb^3＋ complex has brightly green fluorescence in a solid state. At the same time, the energy levels of the excited triplet states for the six ligands were determined to be 22989 -1 cm . The fact that the ligand sensitize Tb^3＋ complexes was explained by the relative energy gap between the lowest triplet energy level of the ligand （T） and ^5Dj of Tb^3＋ or Eu^3＋ . When 2000 cm^-1 〈 △E（T-^5D4） 〈 3000 cm^-1, the luminescent intensity of the Tb^3＋ complex is stronger. When 3000 cm^-1〈 △E （T-^5D1）, the luminescent intensity of the Eu^3＋ complex is weak- er or close to nil. This means that the triplet energy level of the ligand is a chief factor that dominates RE^3＋ luminescence. 相似文献
72.
Shaolong Gong Yonghua Chen Jiajia Luo Chuluo Yang Cheng Zhong Jingui Qin Dongge Ma 《Advanced functional materials》2011,21(6):1168-1178
A series of tetraarylsilane compounds, namely p‐BISiTPA ( 1 ), m‐BISiTPA ( 2 ), p‐OXDSiTPA ( 3 ), m‐OXDSiTPA ( 4 ), are designed and synthesized by incorporating electron‐donating arylamine and electron‐accepting benzimidazole or oxadiazole into one molecule via a silicon‐bridge linkage mode. Their thermal, photophysical and electrochemical properties can be finely tuned through the different groups and linking topologies. The para‐disposition compounds 1 and 3 display higher glass transition temperatures, slightly lower HOMO levels and triplet energies than their meta‐disposition isomers 2 and 4 , respectively. The silicon‐interrupted conjugation of the electron‐donating and electron‐accepting segments gives these materials the following advantages: i) relative high triplet energies in the range of 2.69–2.73 eV; ii) HOMO/LUMO levels of the compounds mainly depend on the electron‐donating and electron‐accepting groups, respectively; iii) bipolar transporting feature as indicated by hole‐only and electron‐only devices. These advantages make these materials ideal universal hosts for multicolor phosphorescent OLEDs. 1 and 3 have been demonstrated as universal hosts for blue, green, orange and white electrophosphorescence, exhibiting high efficiencies and low efficiency roll‐off. For example, the devices hosted by 1 achieve maximum external quantum efficiencies of 16.1% for blue, 22.7% for green, 20.5% for orange, and 19.1% for white electrophosphorescence. Furthermore, the external quantum efficiencies are still as high as 14.2% for blue, 22.4% for green, 18.9% for orange, and 17.4% for white electrophosphorescence at a high luminance of 1000 cd m?2. The two‐color, all‐phosphor white device hosted by 3 acquires a maximum current efficiency of 51.4 cd A?1, and a maximum power efficiency of 51.9 lm W?1. These values are among the highest for single emitting layer white PhOLEDs reported till now. 相似文献
73.
Hameed A. Al‐Attar Gareth C. Griffiths Tom N. Moore Mustafa Tavasli Mark A. Fox Martin R. Bryce Andrew P. Monkman 《Advanced functional materials》2011,21(12):2376-2382
A new family of highly soluble electrophosphorescent dopants based on a series of tris‐cyclometalated iridium(III) complexes (1–4) of 2‐(carbazol‐3‐yl)‐4/5‐R‐pyridine ligands with varying molecular dipole strengths have been synthesized. Highly efficient, solution‐processed, single‐layer, electrophosphorescent diodes utilizing these complexes have been prepared and characterized. The high triplet energy poly(9‐vinylcarbazole) PVK is used as a host polymer doped with 2‐(4‐biphenylyl)‐5‐(4‐tert‐butyl‐phenyl)‐1,3,4‐oxadiazole (PBD) for electron transport. Devices with a current efficiency of 40 cd A?1 corresponding to an EQE of 12% can thus be achieved. The effect of the type and position of the substituent (electron‐withdrawing group (CF3) and electron‐donating group (OMe)) on the molecular dipole moment of the complexes has been investigated. A correlation between the absorption strength of the singlet metal‐to‐ligand charge‐transfer (1MLCT) transition and the luminance spectral red shift as a function of solvent polarity is observed. The strength of the transition dipole moments for complexes 1–4 has also been obtained from TD‐DFT computations, and is found to be consistent with the observed molecular dipole moments of these complexes. The relatively long lifetime of the excitons of the phosphorescence (microseconds) compared to the charge‐carrier scattering time (less than nanoseconds), allows the transition dipole moment to be considered as a “quasi permanent dipole”. Therefore, the carrier mobility is sufficiently affected by the long‐lived transition dipole moments of the phosphorescent molecules, which are randomly oriented in the medium. The dopant dipoles cause positional and energetic disorder because of the locally modified polarization energy. Furthermore, the electron‐withdrawing group CF3 induces strong carrier dispersion that enhances the electron mobility. Therefore, the strong transition dipole moment in complexes 3 and 4 perturbs both electron and hole mobilities, yielding a reduction in exciton formation and an increase in the device dark current, thereby decreasing the device efficiency. 相似文献
74.
Xingdong Wang Shumeng Wang Zhihua Ma Junqiao Ding Lixiang Wang Xiabin Jing Fosong Wang 《Advanced functional materials》2014,24(22):3413-3421
A series of solution‐processible 2,2′‐dimethyl‐biphenyl cored dendrimers, namely G1MP, G2MP, and G3MP, is designed and synthesized by tuning the generation of periphery carbazole dendron. The resulting dendrimers all show excellent solubility in common organic solvents, and their high‐quality thin films can be formed via spin‐coating with a root‐mean‐square roughness in the range of 0.38–0.54 nm. G3MP, which contains the third‐generation carbazole dendron, has the greatest potential among those made here as an ideal universal host for multicolored triplet emitters. G3MP exhibits good thermal stability, with a glass transition temperature of 368 °C, a triplet energy as high as 2.85 eV enough to prevent the loss of triplet excitons, and suitable HOMO/LUMO levels of –5.30/–2.11 eV to facilitate both hole and electron injection and transport. When using G3MP as the host, highly efficient deep‐blue, blue, green, and red phosphorescent organic light‐emitting diodes (PhOLEDs) are successfully demonstrated, revealing a maximum luminous efficiency up to 18.2, 28.2, 54.0, and 12.7 cd A–1 with the corresponding Commission Internationale de L'Eclairage (CIE) coordinates of (0.15, 0.23), (0.15, 0.35), (0.38, 0.59), and (0.64, 0.34), respectively. The state‐of‐art performance indicates that dendritic hosts have a favorable prospect of applications in solution‐processed white PhOLEDs and full‐color displays. 相似文献
75.
Andreas Hohenleutner Susanna Schmidbauer Rudolf Vasold Dominik Joosten Philipp Stoessel Herwig Buchholz Burkhard König 《Advanced functional materials》2012,22(16):3406-3413
This work reports the combinatorial synthesis and screening of phosphorescent iridium complexes as solution processable emitters for OLEDs. The approach taken here allows for the rapid synthesis, isolation, spectroscopic characterization and identification of the libraries based on chromatographic methods. Subsequent analysis of the irradiation induced degradation provides insight on the stability of the complexes under continuous excitation. The method is versatile and can easily be applied to other metal complexes or organic dyes for various applications, e.g., in electroluminescence, photovoltaics and sensing. 相似文献
76.
为了获得低驱动电压、长寿命和高光效的有机电致发光二极管（OLED）,本文介绍了一系列基于1,3,5-三嗪和7,7-二甲基-5,7-二氢茚并［2,1-b］咔唑的新型n型磷光主体材料DTRz、DBTRz和DCNTRz。首先,对它们的电化学性质、光物理性能及热稳定性进行研究,并进行密度泛函理论（DFT）计算。实验与计算分析结果表明：DTRz、DBTRz和DCNTRz具有较高的三线态能级（2.83,2.71,2.72eV）,较高的分解温度（411,499,419oC）,随后与P型主体NBPBC（1∶1）混合后对其光致发光光谱进行研究,并以此为基础,以Pt（BBP）为客体掺杂剂进行了器件制备。器件结果分析表明,DCNTRz∶NBPBC为基础的器件的启动电压为2.1V,最高外量子效率达14.3%,最大亮度达221589cd·m-2,在1000cd·m-2下电流效率最高达46.5cd·A-1,最大功率效率达45.7lm·W-1。特别是在4000cd·m-2下器件寿命（LT95）达282h,比以DTRz∶NBPBC为基础的器件的寿命提高了54%,实现了同时具备低启动电压、高寿命和高光效等优越性能的绿光OLED。 相似文献
77.
室温磷光材料由于其独特的三线态发光机理而具有Stokes位移大、激发态寿命长等特点。然而传统的室温磷光材料多含重金属原子,随之产生的生物毒性问题和环境污染问题限制了其应用。相比之下,纯有机室温磷光材料生产成本低、毒性小,可通过分子工程对有机结构进行灵活的设计和修饰,使其具有更丰富的发光特性,在防伪加密、有机电致发光、生物成像、传感检测等方面具有良好的应用前景。总结了近年来纯有机室温磷光材料在防伪与信息加密及储存、有机电致发光、生物成像、传感检测及其他应用方面的研究进展,并对纯有机室温磷光材料应用尚待解决的问题与未来可能的发展方向进行了简要总结和展望。 相似文献
78.
采用蓝色、黄色磷光混色的发光方式实现白光有机电致发光器件(OLEDS),其中黄色发光层由红色和绿色磷光材料混合而成,器件的结构为ITO/MoO3(30nm)/NPB(40nm)/mCP:FIrpic(8%)(50nm)/CBP:R-4B(1%):GIrl(14%)(xnm)/BCP(10nm)/AlQ(40nm)/LiF(1nm)/Al(100nm)(x=2,3,4,5,6nm)。对器件的效率、亮度等对比发现,当x=5nm时,器件的性能最佳,最大亮度为9 471cd/cm2,效率为23.5cd/A,色坐标(0.32,0.35)。实验表明,影响器件色稳定性和效率低的原因是电子和空穴迁移随驱动电压变化响应不一致引发激子复合区域的移动。 相似文献
79.
80.