利用钆配合物调节激基复合物发光颜色的一种有机发光二极管

报道一种可用钆配合物[Gd（DBM）3bath]调节电致发光（EL）颜色的有机发光二极管（OLED）。该有机发光二极管是在空穴传输层（m-MTDATA）和电子传输层（TPBI）之间插入-薄层Gd（DBM）3bath。随着Cd（DBM）3bath厚度增加,二极管的发光颜色呈现出绿色（主峰525nm）-黄色-橙色（主峰593rim）变化。该二极管的电致发光主要来自界面激基复合物的发射而不是来自各有机功能层;而发光颜色的变化是由于两种激基复合物发射的相对强度的改变。     

LED在自感现象演示实验中的应用

利用发光二极管对自感现象演示实验进行了改进,明显地提高了实验效果,加深了对自感现象的认识。     

氟取代噻咯衍生物结构和光电性能的理论研究

采用密度泛函理论在B3LYP/6-31G(d)水平上计算了1,1-二甲基-2,3,4,5-四苯基噻咯(PSP)及其8种氟取代衍生物的几何结构与光电性质. 计算结果表明, 2,5位苯基上氟取代对PSP结构和光电性质的影响主要由氟原子的取代位置决定, 而取代基个数的增加能加强相关影响. 苯基上邻对位氟取代对分子构型影响较大, 导致HOMO-LUMO能隙增大, 光谱显著蓝移; 而间位氟取代显示诱导作用突出, 使2,5位侧链吸电子能力增强, 同时LUMO能级降低, 电子亲和势增大更有利于电子的注入.     

白光聚合物和聚合物白光器件

有机/聚合物电致发光器件(O/PLEDs)具有低能耗、宽视角、色彩丰富、快速响应、绿色环保以及可制备柔性屏等诸多优异特性,被业界公认为是21世纪最具潜质和最具发展前景的高技术领域之一.白光聚合物电致发光器件(WPLEDs)具有可通过湿法加工技术(如旋涂、丝网印刷、喷墨打印)大大降低器件的制作成本等优点,在显示和照明领域有着极大的应用前景,而受到人们广泛的关注.本文就国内在白光聚合物和聚合物白光器件方面的的研究现状,从聚合物白光器件和制备单一白光聚合物两个方面进行阐述,并介绍这一领域的发展前景和目前亟待解决的一些问题.     

Synthesis, characterization, photophysics and electrophosphorescent applications of phosphorescent platinum cyclometalated complexes with 9-arylcarbazole moieties

A series of cyclometalating platinum(II) complexes with substituted 9-arylcarbazolyl chromophores have been synthesized and characterized. These complexes are thermally stable and most of them have been characterized by X-ray crystallography. The phosphorescence emissions of the complexes are dominated by ³MLCT excited states. The excited state properties of these complexes can be modulated by varying the electronic characteristics of the cyclometalating ligands via substituent effects, thus allowing the emission to be tuned from bright green to yellow, orange and red light. The correlation between the functional properties of these metallophosphors and the results of density functional theory calculations was made. Because of the propensity of the electron-rich carbazolyl group to facilitate hole injection/transport, the presence of such moiety can increase the highest occupied molecular orbital levels and improve the charge balance in the resulting complexes relative to the parent platinum(II) phosphor with 2-phenylpyridine ligand. The solution-processed electrophosphorescent organic light-emitting diodes doped with these platinum-based phosphors have been fabricated which showed a maximum external quantum efficiency of 2.77% for the best device, corresponding to a power efficiency of 3.48 lm/W and a luminance efficiency of 8.49 cd/A. The present work enables the rational design of platinum-carbazolyl electrophosphors by synthetically tailoring the structure of carbazolylpyridine ring that can permit good color-tuning versatility suitable for multi-color display technology.     

Four-coordinate boron compounds derived from 2-(2-pyridyl)phenol ligand as novel hole-blocking materials for phosphorescent OLEDs

Four-coordinate boron compounds of Ph₂B · 1 (2) and (C₆F₅)₃B(1 · H) (3) were prepared from the reaction of 2-(2-pyridyl)phenol (1 · H) ligand with triarylborane starting materials, BPh₃ and B(C₆F₅)₃, respectively, and tested as hole-blocking layer (HBL) materials in phosphorescent OLEDs. While the crystal structure of 2 reveals the pseudo-tetrahedral geometry around the boron center with bidentate [N,O] chelation by 1, 3 is characterized as the zwitterionic four-coordinate system where the ligand 1 · H acts as monodentate [O] chelator with N-protonation. UV-Vis absorption and PL spectra of 2 and 3 are consistent with the ligand-centered, HOMO-LUMO electronic transitions with charge transfer from a phenoxide ring to a pyridine, which was further supported by time dependent DFT calculation for 2. Both compounds are found to possess the HOMO-LUMO energy gap of 3.1 eV appropriate for hole-blocking materials for phosphorescent OLEDs. The devices incorporating 2 and 3 as HBL materials displayed stable green phosphorescence of Ir(ppy)₃ (ppy = 2-phenylpyridine) with low turn-on voltage of 3.2 and 3.4 V, respectively, indicating that 2 and 3 function as HBL materials. Although both devices show the short lifetime (<1 h) probably owing to the low thermal stability, the device based on 2 displays better performances in terms of luminance, power and luminance efficiency, and external quantum efficiency in a wide range of current densities (0.1-100 mA/cm²) than the reference device incorporating BAlq as HBL materials.     

Design and synthesis of new donor-acceptor type conjugated copolymers derived from thiophenes

A new series of donor-acceptor type poly(thiophene) derivatives (P1-P3) were synthesized starting from thiodiglycolic acid and diethyl oxalate through multistep reactions. In the final step, the polymerization was carried out using Wittig reaction. This is a good synthetic route for the preparation of any desired p- and n-type copolymers. The optical and potential charge-transporting properties of the copolymers were investigated by UV-vis, fluorescence emission spectroscopy and cyclic voltammetry. The copolymers exhibited bluish-green/green fluorescence in their thin film forms. Cyclic voltammetry experiments showed that these copolymers have low-lying LUMO energy levels ranging from −2.98 to −3.11 eV and high lying HOMO energy levels ranging from −5.45 to −5.65 eV. The optical and electrochemical studies reveal that new copolymers are new promising materials for the development of efficient polymer light emitting diodes.     

Warm white light from Y4MgSi3O13:Bi, Eu nanophosphor for white light-emitting diodes

Y₄MgSi₃O₁₃:Bi³⁺, Eu³⁺ nanophosphors have been prepared by a facile sol–gel method. The products have been characterized by X-ray diffraction, field-emission scanning electron microscopy and fluorescence measurements. The results show that the nanophosphors are of single phase hexagonal Y₄MgSi₃O₁₃ with size-distribution of 50–90 nm in diameter. White-light emission has been obtained from Bi³⁺ and Eu³⁺ co-doped Y₄MgSi₃O₁₃ nanophosphors upon excitation of 350 nm ultraviolet light. It is noted that Bi³⁺ ions can occupy two different Y³⁺ sites and generate different emissions from the ³p₁ → ¹s₀ transition. Warm white light has been obtained from Y₄MgSi₃O₁₃:Bi³⁺, Eu³⁺ nanophosphors according to Commission International de I’Eclairage (CIE) chromaticity coordinates and color temperature (T_c) with appropriately adjusted contents of Bi³⁺ and Eu³⁺. The results indicate that Y₄MgSi₃O₁₃:0.08Bi³⁺, 0.04Eu³⁺ (x = 0.31, y = 0.31, T_c = 6907 K) are potential nanophosphors for white light-emitting diodes (LEDs) applications.     

有机微腔蓝光发射二极管的研制

利用玻璃/DBR/ITO/NPB/NPB:二萘嵌苯/TAZ/Alq/Al器件结构,研制了有机微腔蓝光发射二极管.将激光染料二萘嵌苯掺于空穴传输材料NPB中作为发光层,Alq为电子传输层,为防止未参与复合的空穴到达金属电极,在NPB:二萘嵌苯和Alq之间引入一薄层TAZ,所研制的微腔器件的峰值位于456 nm,器件表现为较纯的蓝光发射,色坐标为x=0.165,y＝0.088.微腔器件的最大亮度为2 500 cd/m2,最大发光效率为0.23 cd/A.     

Effect of oxygen plasma treatment on the surface properties of tin-doped indium oxide substrates for polymer LEDs

The effect of oxygen plasma treatment on the surface properties of tin-doped indium oxide (ITO) substrates and the changes in surface properties of treated ITO substrates with ageing time were investigated by X-ray photoelectron spectroscopy (XPS), contact angle and surface free energy measurements. Experimental results show that oxygen plasma treatment increases the oxygen concentration, decreases the carbon concentration, and enhances the surface free energy and polarity, and thereby improves the surface properties of ITO substrates. However, the improved ITO surface properties tended to decay and the surface free energy decreased, with ageing time. In addition, the ageing effect of treated ITO substrates on the performance of polymer light-emitting diodes (LEDs) was studied with respect to the driving voltage, electroluminescent luminance and efficiency. We observe that the ITO substrates aged for various times result in significant differences in optical and electrical characteristics which become worse as the ageing time increases. The optical and electrical performance of polymer LEDs is closely related to the surface properties of ITO substrate and the interface characteristics of ITO/polymer.