高效率和色稳定性的双超薄发光层的黄光有机电致发光器件

主要对rubrene黄光发光材料制作0.1nm厚度的超薄发光层的有机电致发光器件作了研究,并配合BCP空穴阻挡层探讨了对器件效率和色坐标稳定性的影响。双超薄rubrene发光层配合BCP空穴阻挡层的有机电致发光器件的性能得到了很好的改善,外加电压6V时,器件电流效率为6.35cd.A-1;外加电压10V时,器件发光亮度达到了7068cd.m-2。另外,在较大的外加电压驱动范围内,器件的色坐标一直保持在(0.49,0.49)。增加的发光效率和良好的色坐标稳定性主要是取决于空穴与电子的注入与输运平衡以及激子在超薄rubrene发光层中稳定性的复合平衡。     

基于液体基质材料的有机电致发光器件的制备及性能分析

利用液体基质材料9-(2-ethylhexyl)carbazole(EHCz)掺杂有机染料分子5,6,11,12-tetraphenyl-nathacene(rubrene)制备了具有液体发光层的有机电致发光器件,其结构为:ITO/PEDOT:PSS/EH Cz:rubrene/Cs2CO3/ITO,PEDOT:PSS...     

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     

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     

掺杂型红色有机电致发光显示器件

全色显示是有机电致发光显示(OLED)器件发展的目标,而高性能红色发光器件一直是制约全彩色OLED器件实用化的瓶颈,也是目前有机电致发光显示研究的热点。制作了掺杂DCJTB和不同浓度的rubrene两种荧光染料的红色有机电致发光显示器件,以NPB和Alq₃分别作为空穴传输层和电子传输层,发现器件性能与只掺杂DCJTB的器件相比有明显提高,发光效率提高到2～3倍。通过Frster理论和能带理论分析了器件的能量转移机理,研究发现Frster能量转移不是掺杂器件能量转移的主要形式,载流子俘获机制才是器件效率提高的主要原因;rubrene的引入使得能量能够更有效地从Alq₃转移到DCJTB,从而显著地提高了器件的发光效率和性能。     

TBPe作蓝光材料的双层白色有机电致发光器件的性能

选用一种新型高效的蓝光有机小分子荧光染料TBPe,首次制备了以PVK:TBPe为蓝光发光层和Alq₃:rubrene为橙红光发光层的双层白光有机电致发光器件,器件结构为ITO/PVK:TBPe/Alq₃:rubrene/Mg:Ag。通过适当调节各有机层的掺杂比例和厚度,得到了发光性能比较理想的白光器件。器件在7V左右启亮,而且随着外加电压的变化,色坐标基本保持不变,在外加驱动电压为16V时,器件的亮度为738cd/m²,外量子效率为0.2%。我们还尝试选用本身可以发绿白光,而且兼具电子传输特性的母体材料Zn(BTZ)₂替代Alq₃,器件的最大亮度提高到1300cd/m²,色坐标为(0.32,0.36),更加接近白色等能点,器件其他光电性能也得到了显著地提高。     

用于光通信的高速响应有机电致发光器件

采用直接光强调制的方法,建立了一种新型有机电致发光器件(OLED)的光电信号传输体系,研究了发光层掺杂、发光面积和预置电压对OLED响应速度的影响。结果发现:与发光层为单独的Alq3的器件相比较,掺杂rubrene的发光层的荧光寿命较短,响应较快;减小OLED的发光面积能提高OLED的响应速度,并在0.02 mm2的发光面积上实现了100 Mbit/s的信号传输速度;同时,预置直流电压也能改善OLED的响应速度。最后,提出将柔性OLED与聚合物波导及有机光电二极管结合,实现了一种全有机的柔性光电子体系。     

有机电致发光白光器件的研究进展

在十多年的时间里,有机电致发光二极管(Organic Lightemitting Diodes,OLEDs)的研究和应用取得了长足的进展。有机电致发光器件具有许多优点,例如:自发光、视角宽、响应快、发光效率高、温度适应性好、生产工艺简单、驱动电压低、能耗低、成本低等,因此有机电致发光器件极有可能成为下一代的平板显示终端。有机电致发光白光器件因为可以用于全彩色显示和照明,已成为OLED研究中的热点。介绍了有机电致发光白光器件的研究进展,按发光的性质将白光器件分为荧光器件和磷光器件两类,按发光层数将白光器件分为单层和多层器件,对相关材料、器件结构、发光机理等方面进行了讨论。     

DPVBi的厚度和发光位置不同对有机电致发光器件性能的影响

通过调整发光层DPVBi的厚度和在器件中的位置,在同一实验条件下设计了不同的器件结构,制备了有机电致发光器件,在实验中可看到DPVBi的厚度不同,器件的色度发生了改变,并且发现DPVBi在器件的不同位置,器件的发光特性也是不同的。通过实验可以得知处于器件不同位置的DPVBi,其发光机理是不同的,这是由于DPVBi和Alq3的最高未占有轨道(HOMO)能级相差不多,而它们的最低占有轨道(LUMO)能级相差0.4eV,这样DPVBi的存在有利于电子的注入,同时由于rubrene和DPVBi的HOMO相差0.5eV,这样空穴和电子就在rubrene和DPVBi的界面处形成激子复合而发光。也就是说,在rubrene之后的DPVBi对空穴有了阻挡作用,使器件中的空穴和电子达到平衡。通过改变DPVBi的厚度,制备了白光器件,这组白光器件,在7～17V变化范围内器件的色坐标从(0.35,0.37)到(0.33,0.35)变化不大,接近白光等能点(0.33,0.33),是色度比较好的器件。     

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     

Organic single-quantum-well electroluminescent device

A new kind of single-quantum-well electroluminescent (EL) device consists of a hole transport N,N-Bis(3-methyphenyl)-N,N-diphenylbenzidine(TPD) layer, and electron transport 8-(quinolinolate)-aluminum(Alq) layer and a light emitting layer of Alq doped with 5,6,11,12-tetraphenylnaphthacene (rubrene) has been fabricated by the multisource-type high-vaccum organic molecular deposition. The dopant rubrene is as a potential well, and the undoped Alq layer is as a barrier layer. The EL spectra shows the spectral narrowing and the emission peak energy blue-shift, and the efficiency and luminance of the device have been significantly improved. The experimental phenomena is explained as the result of recombination of carriers from the quantized energy state.     

Efficient bright white organic light-emitting diode based on non-doped ultrathin 5,6,11,12-tetraphenylnaphthacene layer

High-performance undoped white organic light-emitting diode (OLED) has been fabricated using an ultrathin yellow-emitting layer of 5,6,11,12-tetraphenylnaphthacene (rubrene) inserted at two sides of interface between two N,N′-bis-(1-naphthyl)-N,N′- biphenyl-1,1′-biphenyl-4,4′- diamine (NPB) layers as a hole transporting and blue emissive layer, respectively. The results showed that a maximum luminance of the device reached to as high as 21,500 cd/m² at 15 V. The power efficiencies of 2.5 and 1.6 lm/W at a luminance of 1000 and 10000 cd/m², respectively, were obtained. The peaks of electroluminescent (EL) spectra locate at 429 and 560 nm corresponding to the Commissions Internationale De L’Eclairage (CIE) coordinates of (0.32, 0.33), which is independent of bias voltage. The performance enhancement of the device may result from direct charge carrier trapping in rubrene. Energy transfer mechanism was also found in the EL process.     

Highly efficient and bright doped organic electroluminescent diodes using an aluminum electrode

Remarkable improvement in efficiency and electroluminescence (EL) has been observed in an organic EL device, which consists of a hole-transport layer and a luminescent layer. The hole-transport layer is an N,N-bis(3-methyphenyl)-N,N-diphenylbenzidine film. The doped emitting layer consists of 8-(quinolinolate)-aluminum as the host and rubrene as the emission dopant. The doped cell with aluminum cathode demonstrated a luminance in excess of 20,000 cd/m² and an external quantum efficiency of 2.7%, which is about four times and three times, respectively, greater than those of the undoped cell. The EL emission from the device shows spectral narrowing and a shift to higher energy.     

Abrupt change of luminescence spectrum in single-layer phosphorescent polymer light emitting diode

PVK-based single-layer phosphorescent polymer OLEDs (organic light emitting diodes) with different rubrene concentrations were fabricated and examined for the Förster energy transfer from phosphorescent FIrpic dye to rubrene. We found out that at a certain rubrene concentration the energy transfer occurs abruptly and the transfer shows an abnormal evolution of electroluminescence (EL) spectrum due to the coincidence of peak wavelengths of bis[(4,6-difluorophenyl)-pyridinato-N,C^2′](picolinate) iridium(III) (FIrpic) emission and 5,6,11,12-tetraphenylnaphthacene (rubrene) absorption. With the calculation of Förster radius and average distance between FIrpic molecules, we have related the calculated ratio between the number of FIrpic molecules within to that out of Förster radius with the degree of Förster energy transfer from EL spectra measured in the experiment. Experimental results were found to fit well with the predicted results especially at low rubrene concentrations.     

溶液法制备PVP为界面修饰层的红荧烯结晶性薄膜

为了获得低成本、高结晶度的红荧烯薄膜,采用溶液加工的方法和聚合物界面修饰层研究了红荧烯薄膜的性质。首先,通过旋涂方法在Si/SiO₂衬底上先沉积一层聚乙烯吡咯烷酮（PVP）作为界面修饰层,利用偏光显微镜（POM）、原子力显微镜（AFM）研究了PVP层表面形貌及粗糙度。接着在PVP上滴涂红荧烯溶液后固化烘干,制备红荧烯晶体薄膜,研究了不同PVP浓度和不同成膜温度下界面修饰层对红荧烯表面形貌的影响。然后,利用X射线衍射（XRD）表征对比研究了薄膜的微观结构。最后,分析了红荧烯晶体薄膜的生长机制。实验结果表明：80~140℃及低浓度的PVP条件下能得到结晶度高、连续的红荧烯球晶,并且温度升高时,球晶尺寸变大。PVP作为界面修饰层有利于改善红荧烯的成膜性,制备高结晶度的晶体薄膜。     

Optical properties of a novel yellow fluorescent dopant for use in organic LEDs

In this paper, the optical properties of a novel organic, 2,8-di(t-butyl)-5,11-di[4(t-butyl) phenyl]-6,12-diphenylnaphthacene (tetra(t-butyl)rubrene) have been investigated. Our results show that there are two peaks in the photoluminescence (PL) spectra of tetra(t-butyl)rubrene (TBRb) which are also confirmed in the electroluminescence (EL) spectra. Photo-quenching of the PL intensity is observed when the irradiation time increases. It is shown that oxidation is the dominant reason for photo-quenching. The absolute refractive index and absorption coefficient have also been determined and the results correlate well with the PL results. The results show that TBRb can be a good dopant to achieve the Förster energy transfer and to assist light emission. The optical properties of TBRb are similar to those of rubrene; however, the PL of TBRb is much stronger than that of rubrene. Finally, although crystalline organics have been commonly reported by heating the sample, we report crystallization of TBRb at low temperature <230 K when the TBRb film is in an amorphous form before cooling. PACS 78.47.+p; 78.55.-m; 81.05.Lg; 85.60.-q     

Rubrene作电子传输层的异质结有机太阳能电池

以Rubrene为电子传输层(ETL),制备了结构为ITO/MoO3(5nm)/Rubrene(50nm)/C60(45nm)/Rubrene(0,3,5.5,9.5nm)/Al(130nm)的有机太阳能电池.与没有ETL的器件相比,含5.5nmRubrene的电池的开路电压、填充因子、功率转换效率分别从0.68V,0.488,0.315%增加到0.86V,0.574,0.490%.实验结果分析表明:热的Al原子直接沉积在C60上,破坏了C60层,形成高功函数的C60/Al阴极,弱化内建电场,降低电池性能;当插入ETL后,C60层得到保护,热的Al原子沉积破坏了Rubrene层,形成了缺陷态能级,提高电池的内建电场,促进了电子的传输.进一步的单电子电池实验表明,缺陷态能级低于C60的最低未占据分子轨道.     

Nondoped-type White Organic Light-Emitting Diode Using Star-Shaped Hexafluorenylbenzene as an Energy Transfer Layer

采用真空蒸镀的方法以星形六苯芴类新材料1,2,3,4,5,6-hexakis(9,9-diethyl-9H-fluoren-2-yl)benzene(HKEthFLYPh)作为能量传输层制备了indium-tin-oxide(ITO)/N,N′-bis-(1-naphthyl)-N,N′-diphenyl-(1,1'-biphenyl)-4,4′-diamine(NPB)/HKEthFLYPh/5,6,11,12-tetraphenylnaphtacene(rubrene)/tris(8-hydroxyquinoline) aluminum (Alq3)/Mg:Ag的白色有机电致发光器件. NPB和Alq3分别作为蓝色发光层和电子传输层,NPB和Alq3之间的超薄Rubrene层 作为黄色发光层. 结果表明,超薄rubrene层改善了白光器件的色纯度与稳定性,器件的光谱及色坐标几乎不随驱动电压的变化而改变.当rubrene层厚度为0.3 nm时,器件的Commissions Internationale De L′Eclairage (CIE)色坐标为(0.32,0.33). 驱动电压为18 V时,器件的最大亮度为4816 cd/m2.