一种红光螯合电磷光聚合物光电性能的研究

研究了螯合电磷光聚合物PFBtpIrm的光致发光、电化学和电致发光特性,并通过优化器件结构提高聚合物的电致发光性能.发现在聚合物中加入PBD使发光效率降低;而加入PVK空穴传输层后,由于能量有效地转移到电磷光聚合物中,器件性能提高.基于器件ITO/PEDOT/PVK/ PFBtpIrm5/Ba/Al,在电流密度为10.0mA/cm²时,最大外量子效率为4.25%,饱和红光的色坐标为(0.69,0.29). 关键词： 电致磷光 聚合物发光二极管 电子传输材料 空穴传输材料     

高效磷光聚合物发光二极管的实现

在有机及聚合物电致发光器件中 ,三重态发光 (磷光 )可以获得较高的量子效率 ,已在有机发光二极管平板显示中得到了广泛的应用。从能量传输的角度分析了提高磷光聚合物发光二极管器件发光效率的主要方法 ,综述了高效磷光聚合物发光二极管的实现途径与进展。     

高效率共轭聚合物主体绿光磷光发光二极管

因电致发光效率高和器件制备工艺简单,聚合物为主体的绿色磷光电致发光成为一个研究热点.共轭聚合物的三线态能级一般低于绿色磷光材料的三线态能级,易对磷光的发光引起猝灭导致低的发光效率,所以较少被用作绿色磷光材料的主体.通过增加聚乙烯基咔唑（PVK）作为空穴传输层,获得了高发光效率的共轭聚合物聚芴（PFO）作主体绿色磷光发射,甚至高于相同条件下以PVK为主体的绿色磷光发射.究其原因,PVK的电子阻挡作用使发光中心靠近PVK与PFO的界面,界面处PVK因为其高的三线态能级增强了绿色磷光的发光.当三-（2-苯基吡啶）-Ir（Ir（ppy）₃）掺杂浓度为2％时得到了最高的亮度效率24.8 cd/A,此时的电流密度为4.65 mA/cm²,功率效率为11 lm/W,最高亮度达到35054 cd/m²,色坐标是（0.39,0.56）. 关键词： 共轭聚合物 磷光 绿光发光     

不同主体双发光层白色有机电致发光器件的性能研究

制备了结构为ITO/NPB/CBP:TBPe:rubrene/BAlq:Ir(piq)₂(acac)/BAlq/Alq₃/Mg:Ag的白色磷光有机电致发光器件.利用两种不同的主体材料,即用双载流子传输型主体材料CBP掺杂荧光染料TBPe及rubrene作为蓝光和橙黄光发光层;用电子传输型主体材料BAlq掺杂磷光染料Ir(piq)₂(acac)作为红色发光层.以上双发光层夹于空穴传输层NPB与具有电子传输性的阻挡层BALq之间.讨论了如何控制 关键词： 有机电致发光 磷光染料 掺杂 白光     

Spectral Characteristics of White Organic Light-emitting Diodes Based on Novel Phosphorescent Sensitizer

采用新型贵金属铱的配合物bis(1,2-dipheny1-1H-benzoimida-zole)iridium (acetylacetonate)作为磷光敏化剂,与荧光染料4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-en-yl)-4H-pyran共同掺杂到聚合物主体材料poly(N-vinylcarbazole)中,以N,N'-diphenyl-N,N'-bis(1-naphthyl) (1,1'-biphenyl)-4,4'-diami-ne作为蓝光发光层,制备了白色有机电致发光器件. 通过对掺杂体系的紫外-可见吸收光谱、光致发光光谱以及电致发光光谱的表征,分析了该磷光敏化体系的能量转移机制. 结果表明,在该聚合物磷光荧光双掺杂体系中,由于磷光与荧光材料之间的不完全的F?rster能量传递过程,导致电致发光光谱中同时存在磷光材料三线态到基态与荧光材料单线态到基态的辐射衰减发光. 该掺杂体系成功实现了白光发射,随着偏置电压的升高,器件的CIE色坐标有微小的红移,但都非常接近等能白光点,器件表现出了很好的色纯度.     

一种多层白色磷光有机电致发光器件的制备及性能研究

制备了一种结构为ITO/NPB/NPB:Ir(piq)₂(acac)/CBP:TBPe/BAlq:rubrene/BAlq/Alq₃/Mg:Ag的白色磷光有机电致发光器件.其中空穴传输型主体NPB掺杂磷光染料Ir(piq)₂(acac)作为红色发光层,双载流子传输型主体4,4′-N,N′-dicarbazole-biphenyl (CBP)掺杂TBPe作为蓝色发光层,电子传输型主体材料BAlq掺杂rubrene作为绿色发光层.以上发光层夹于 关键词： 电致发光 磷光染料 异质结 白光     

有机小分子发光材料与聚合物发光材料在大气存放条件下的稳定性对比研究

分别采用紫外光电子能谱（UPS）、X光电子能谱（XPS）、原子力显微镜（AFM）、以及光致发光光谱（PL）等方法对在大气存放条件下的8－羟基喹啉铝（Alq)薄膜和聚（9,9－二辛烷基芴）（PFO）薄膜的电子结构、表面形 及发光特性进行了对比。研究结果表明,PFO的电子结构、表面形貌以及发光特性受外界气氛影响极小,是一种非常稳定的聚合物发光材料。这为聚合物发光器件的稳定性提供了有利的条件。     

基于Alq_3掺杂Bphen电子传输层的有机发光二极管

制备了结构为ITO/MoO_3(30 nm)/NPB(40 nm)/TCTA(10 nm)/CBP∶R-4B(8%)(30 nm)/电子传输层(40 nm)/Li F(1 nm)/Al(150 nm)的器件,其中R-4B为红色磷光染料,电子传输层分别采用Alq_3、Bphen∶Alq_3(x%)和Bphen,对3种不同电子传输层器件的发光性能进行了研究。结果表明:Bphen∶Alq_3(x%)作为电子传输层的器件与Alq_3或Bphen作为电子传输层的器件相比,亮度提高了约3.5倍,电流效率提高了1.1~2.5倍,效率滚降变得平缓。采用Bphen∶Alq_3作为电子传输层,不仅减小了电子在LUMO能级传输时的跳跃传输距离,而且在一定程度上抑制了Bphen的结晶,使器件的电子传输能力和效率滚降性能得到改善。     

空穴传输层掺杂SrF2的高效率蓝色磷光OLED器件

通过在OLED器件的空穴传输层中掺杂不同比例的SrF2制作出了高效率蓝色磷光OLED器件.这种器件能有效提高蓝色磷光OLED器件的空穴注入与传输特性,降低器件的的工作电压,提高流明效率(19.11m/W)、电流效率(26.9 cd/A)以及亮度(22 220 cd/m2),和未经掺杂的参比器件相比,分别提高了85.4％...     

不同主体双发光层白色有机电致发光器件的性能研究

制备了结构为ITO/NPB/CBP:TBPe:rubrene/BAlq:Ir(piq)₂(acac)/BAlq/Alq₃/Mg:Ag的白色磷光有机电致发光器件.利用两种不同的主体材料,即用双载流子传输型主体材料CBP掺杂荧光染料TBPe及rubrene作为蓝光和橙黄光发光层;用电子传输型主体材料BAlq掺杂磷光染料Ir(piq)₂(acac)作为红色发光层.以上双发光层夹于空穴传输层NPB与具有电子传输性的阻挡层BALq之间.讨论了如何控制     

PBD在稀土配合物与PVK混合体系电致发光中的作用

研究了PBD以较低浓度与铽配合物[Tb(m-MBA)₃phen]₂·2H₂O、PVK共掺杂体系的电致发光,制作了两类电致发光器件：ITO/PVK:Tb complex/PBD/LiF/Al,ITO/PVK：Tb complex:PBD/PBD/LiF/Al。在共掺杂的发光层中铽配合物的电致发光来源于两个途径,一个是由PVK到铽配合物的能量传递,另一个是电子和空穴在铽配合物上直接复合发光。改变PBD在发光层中的掺杂比例,制得一系列器件,通过对其光谱和亮度的研究,发现PBD在较低浓度掺杂时器件的稳定性和亮度随掺杂浓度的增加而降低。通过分析认为PBD的加入对给体(PVK)到受体(Tb complex)的能量传递效率影响较小,主要是由于PBD的加入使得电子和空穴在PVK链间的跳跃受到限制,使在由PVK、铽配合物和PBD三者掺杂组成的发光层中,注入的电子和空穴不能有效地在铽配合物上复合,这样就会减少激子在铽配合物上直接复合的概率,而造成器件的亮度和效率降低。     

The effect of driving voltage on the electroluminescent property of a blend of poly(9-vinylcarbazole) and 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole

The impact of driving voltage on the electroluminescence (EL) from organic light emitting diode with ITO/PVK:PBD:TBAPF₆(10:10:1)/Al structure was analyzed by the method of Gaussian fitting. Indium tin oxide (ITO) was used as anode, poly(9-vinylcarbazole) (PVK) as polymeric host, 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) as electron-transporting molecule, tetrabutylammonium hexafluorophosphate (TBAPF₆) as organic salt and aluminium (Al) as cathode. A broad EL has been observed and it could be attributed to the overlap of emission from four different excited state complexes, including PVK:PBD exciplex, PVK:PBD electroplex, PBD electromer and PVK electromer. The EL spectra shifted to longer wavelength with the increase of driving voltage. The ratio of PVK electromer to PVK:PBD exciplex emission intensity first declined slightly and then increased remarkably, while the relative intensity of combination of PVK:PBD electroplex and PBD electromer emission remained unchanged when the voltage was increased.     

Enhanced Green Electrophosphorescence from Oxadiazole-Functionalized Iridium Complex-Doped Devices Using Poly（9,9-Dioctylfluorene） Instead of Poly（N-Vinylcarbazole） as a Host Matrix

Optoelectronic properties of the oxadiazole-functionalized iridium complex-doped polymer light-emitting devices （PLEDs） are demonstrated with two different polymeric host matrices at the dopant concentrations 1-8%. The devices using a blend of poly（9,9-dioctylttuorene）（PFO） and 2-（4-biphenyl）-5-（4-tert-butylphenyl）-1,3,4-oxadiazole （PBD） as a host matrix exhibited a maximum luminance efficiency of 11.3 cd/A at 17. 6 mA/cm^2. In contrast, the devices using a blend of poly（N-vinylcarbazole） （PVK） and PBD as a host matrix reveal only a peak luminance efficiency of 6.Scd/A at 4.1 mA/cm^2. The significantly enhanced electrophosphorescent emissions are observed in the devices with the PFO-PBD blend as a host matrix. This indicates that choice of polymers in the host matrices is crucial to achieve highly efficient phosphorescent dye-doped PLEDs.     

One-step synthesis of silica-coated magnetite nanoparticles by electrooxidation of iron in sodium silicate solution

In the present study, solid-solution gold?Cplatinum (Au?CPt) nanoparticles with controllable compositions were fabricated by high-intensity femtosecond laser irradiation of an aqueous solution of gold and platinum ions without any chemicals and complicated processes. Transmittance electron microscopy revealed that the single nanometer-sized particles were fabricated by femtosecond laser irradiation of mixed aqueous solutions of gold and platinum ions. The crystalline structure of nanoparticles was characterized by electron and X-ray diffractions. Contrary to the bulk Au?CPt binary systems, which commonly contain a pair of diffraction peaks between pure gold and platinum peaks because of its large miscibility gap in phase diagram, or mixture of Au and Pt, the diffraction peaks of Au?CPt nanoparticles fabricated in the experiment showed a characteristic of the fcc-type lattice. Moreover, the diffraction patterns shifted monotonically from the peak position of pure gold to that of pure platinum as the fractions of platinum ions in the solution were increased. These observations strongly imply that the Au?CPt nanoparticles were solid solution with intended compositions. This technique is not only simple and environmentally friendly, but also applicable to other binary and ternary systems.     

Influence of tetrabutylammonium hexafluorophosphate (TBAPF6) doping level on the performance of organic light emitting diodes based on PVK:PBD blend films

The effect of doping level of tetrabutylammonium hexafluorophosphate (TBAPF₆) on the performance of single-layer organic light emitting diodes (OLEDs) with ITO/PVK:PBD:TBAPF₆/Al structure were investigated where indium tin oxide (ITO) was used as anode, poly(9-vinylcarbazole) (PVK) as hole-transporting polymeric host, 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) as electron-transporting molecule and aluminium (Al) as cathode. It was found that the doped devices underwent a unique transition at the first voltage scan as indicated by drastically increasing of current at certain applied voltage. After the transition, the threshold voltage for current injection as well as the turn-on voltage decreased significantly as compared to the undoped device. The current injection threshold voltage and turn-on voltage decreased with the increase of TBAPF₆ doping level. More importantly, a relatively low current injection threshold voltage of 3 V has been achieved by doping a significant amount of TBAPF₆ (weight ratio greater than five) in the single-layer OLED based on PVK:PBD blend films with high work function Al metal as cathode. The significant improvement was attributed to the reduction of both electron and hole injection energy barriers caused by accumulation of ionic species at the interface.     

混合发光层有机电致发光器件中的多重成分发射

以等摩尔空穴传输材料TPD和电子传输材料PBD组成结构为ITO/TPD/TPD∶PBD/PBD/Al的混合物发光层有机电致发光(EL)器件,观察到了相对于组成材料的荧光光谱红移的宽发射带。通过比较EL光谱,光致发光光谱及EL光谱分解,表明电致发光中同时包含单体发射、激基复合物和电荷对复合物的发射。激基复合物为TPD的激发态TPD*与PBD的基态相互作用形成TPD*PBD类型的复合物,电荷对复合物是带电荷的空穴传输分子(D+)的空穴和电子传输分子(A-)的电子交叉复合而形成的(D+-A-)*复合物。各激发态在电场作用下呈现不同的形成机理和复合过程,并且单体发射和激发态复合物的比例随电场而变化,导致发射光谱随电场增强而蓝移。该器件的最高亮度和最大外部量子效率分别为240 cd·(cm2)-1和0.49%。有机固态界面激基复合物或电荷对复合物的发射常出现宽的红移发射带,是调节发光颜色的有效手段。     

Photophysical characterizations of 2-(4-biphenylyl)-5 phenyl-1,3,4-oxadiazole in restricted geometry

Langmuir and Langmuir-Blodgett (LB) films of non-amphiphilic 2-(4-Biphenylyl)-5-phenyl-1,3,4-oxadiazole (abbreviated as PBD) mixed with stearic acid (SA) as well as with the inert polymer matrix poly(methyl methacrylate) (PMMA) have been studied. Surface pressure versus area per molecule (π-A) isotherm studies suggest that PBD molecules very likely stand vertically on the air-water interface and this arrangement allows the PBD molecules to form stacks and remain sandwiched between SA/PMMA molecules. At lower surface pressure, phase separation between PBD and matrix molecules occurs due to repulsive interaction. However, at higher surface pressure, PBD molecules form aggregates. The UV-vis absorption and steady-state fluorescence spectroscopic studies of the mixed LB films of PBD reveal the nature of the aggregates. H-type aggregate predominates in the mixed LB films, whereas I-type aggregate predominates in the PBD-PMMA spin-coated films. The degree of deformation produced in the electronic levels are largely affected by the film thickness and the surface pressure of lifting.     

一种新型的稀土Tb配合物的光致和电致发光性能的研究

用一种新型的含酚羟基的Schiff碱三足配体H₃L3稀土Tb配合物作发光层制备了三层结构电致发光器件,器件在正向直流偏压下发出明亮的绿光。器件的电致发光(EL)光谱和Tb配合物薄膜的光致发光(PL)光谱与典型的Tb配合物的发光光谱相同。研究了器件发光及电学特性,讨论了该种新型的稀土Tc配合物的发光机理。     

碳纳米管受限空间对共轭高分子聚(9,9-二辛基芴-2,7-二基)链段运动行为的影响

在纳米受限空间中,高分子往往会表现出与本体状态不同的性质,如异常的链段运动特性及晶相间转变行为等,这些性质对于研究和开发新型高分子材料具有重要的意义,因此针对受限环境下高分子的物理化学特性研究也一直是高分子界关注的焦点.本文通过化学气相沉积法制备垂直取向排列的多壁碳纳米管阵列,借助溶剂润湿–收缩法获得规整的高密度阵列结构,其取向排列的碳纳米管间隙形成了准一维的纳米受限空间,尺寸在5—50 nm尺度下可调.进一步将共轭高分子聚(9,9-二辛基芴-2,7-二基)(PFO)填充到碳管间隙的纳米空间中,制备PFO与取向多壁碳纳米管阵列复合膜.结果发现在碳纳米管形成的纳米受限空间中,PFO的链段热运动行为与本征态PFO薄膜相比受到了明显的抑制,不同晶型间转变速度大大减缓,提高了构象的热稳定性,同时取向排列的碳纳米管对PFO分子链取向排列分布具有明显的诱导作用,有利于获得高性能的PFO晶体.这种高密度取向排列的碳纳米管阵列结构未来可以用于制备优良发光性能及高稳定性的PFO光电器件.     

PBD的掺杂对PVK:Ir(ppy)3体系发光特性的影响

从三线态激子的发光机理入手,研究了PBD作为电子传输材料对PVK:Ir(ppy)3体系的影响。实验中制备了单层器件ITO/PVK:Ir(ppy)3/PBD/Al,ITO/PVK:Ir(ppy)3:PBD/Al和双层器件,ITO/PVK:Ir(ppy)3:PBD/BCP/Al,其中PVK:Ir(ppy)3的掺杂浓度比例不变,通过改变PBD的掺杂浓度,其变化范围是PBD与PVK的质量比从0:100到20:100,制得了一系列器件,研究了它们的光致发光(PL)光谱和电致发光(EL)光谱。发现PBD这种电子传输材料的加入对器件的亮度有很大提高,当PBD与PVK质量比为10%时,器件亮度最大。