多色有机薄膜电致发光器件及其稳定性

研究了绿色、红色、蓝色和白色四种有机薄膜电致发光器件。通过掺杂得到了高稳定性的绿色及红色器件 ,绿色器件的半寿命达 140 0 0h(初始亮度 10 0cd/m2 ) ,红色器件的半寿命为 75 0 0h(初始亮度 5 0cd/m2 )。还研究了具有空穴锁定层及非锁定层的两种不同结构的蓝色及白色器件。研究表明无论蓝色还是白色器件 ,具有空穴锁定层的器件稳定性较差 ,老化过程中界面势垒的变化很大。非锁定层的蓝色及白色器件的半寿命分别为 45 0h(初始亮度 5 0cd/m2 )和 30 0h(初始亮度 5 0cd/m2 )。在稳定性改善的基础上研制成功 96× 6 0线 ,分辨率为 2线 /mm的绿色矩阵显示屏 ,设计和研制了驱动及控制电路 ,实现了动态显示     

染料掺杂的红色有机薄膜电致发光器件

近年来 ,有机发光二极管 (OL EDs)得到了广泛深入的研究[1～ 3] 。研究工作主要集中在探索新的有机荧光材料、载流子注入和输运材料 ,以及器件的新结构 ,力求得到发光效率高和稳定性好的各种不同颜色的发光。从目前的研究来看 ,尽管蓝色和绿色发光材料的效率已经足够高到实用 ,但红色发光材料仍然存在问题 ,对红色发光进行研究是非常必要的。有两条实现红色发光的途径 :掺杂能发红光的染料和用稀土离子配合物作基质或激活剂。利用能量传递的原理 ,在有机基质材料中掺杂荧光染料是获得高效、长寿命和所希望发光颜色的一种有效而简单的方法…     

彩色有机薄膜电致发光及动态矩阵显示

研究了绿色、红色、蓝色和白色4种有机薄膜电致发光器件.通过掺杂得到了高稳定性的绿色及红色器件,绿色器件的半寿命达14000小时(初始亮度100cd/m²),红色器件的半寿命为7500小时(初始亮度50cd/m²).还研究了具有空穴锁定层及非锁定层的多种不同结构和材料的蓝色及白色器件.研究表明无论蓝色还是白色器件,具有空穴锁定层的器件稳定性较差,老化过程中界面势垒的变化很大.非锁定层的蓝色及白色器件中,新材料JBEM比DPVBi有更优越的性能.JBEM构成的蓝色器件的半亮度寿命为1035小时(初始亮度100cd/m²).由JBEM构成的白色器件中,由蓝色及红色掺杂在同一层的器件得到最好的稳定性,其半亮度寿命为2800小时(初始亮度100cd/m²),而且它具有发光颜色不随电流变化而变化的特点.在稳定性改善的基础上研制成功96×60线,分辨率为2线/mm的绿色及白色矩阵显示屏,还利用选择蒸发的方法制造了彩色矩阵屏,设计和研制了驱动及控制电路,实现了动态显示.     

以蓝色发光材料DPVBi为基质的白色发光器件

白色有机发光器件是实现彩色平板显示的重要方案之一。利用蓝色发光材料DPVBi[4，4′—(2，2—苯乙烯基)—1，1′—联苯]掺杂红光染料DCJTB[4—氰甲烯基—2—叔丁基—6—(1，1，7，7—四甲基久洛尼定基—9—烯炔基—4H—吡喃)]作发光层制备了白色发光器件。研究了DPVBi掺杂不同浓度IDCJTB薄膜的光致发光性质，根据光致发光结果，制备了以DPVBi掺杂不同浓度DCJTB作发光层的电致发光器件，其结构为ITO／GuPc／NPB／DPVBi：DCJTB／Alq3／LiF／Al。当DCJTB质量分数为0．0008时，器件实现了白色发光(色度x=0．25，y=0．32)，电致发光和光致发光的掺杂比例基本相符，表明器件的白色发光主要是由基质DPVBi向掺杂剂DCJTB的能量传递产生的。研究还发现：白色器件随电压升高，光谱中蓝色成分相对于红色成分的比例略有增加，文章对此现象进行了分析。该白光器件在14V时达到最高亮度7822cd／cm^2，在20mA／cm^2电流密度下的亮度为-489cd／cm^2，最大流明效率为1．75lm／W。     

稳定的光谱不随电流变化而改变的白色有机发光器件

使用新材料构成了两种结构白色有机薄膜电致发光器件，一种是蓝色及红色发射在同一层中，另一种是蓝色发射和红色发射分别在两层中，器件结构分别为ITO／CuPc／NPB／JBEM（P）：DCJT／Alq／MgAg（器件1）和ITO／CuPc／NPB／JBEM（P）／Alq：DCJT／Alq／MgAg（器件2）。这里（CuPc）是空穴注入层；N，N’－bis－（1－naphthyl）－N，N’－diphenyl－1，1’bipheny1－4－4’－diamine（NPB）是空穴传输层（HTL）；9，10－bis（3’5’－diaryl）phenyl anthracene（JBEM）是蓝色发射层；tris（8－quinolinolato）aluminium complex（Alq）是电子传输层（ETL）；DCJT是红色染料。在器件1中得到稳定的且色度不随电流增在而变化的白色发射。它的最大亮度为14850cd/m^2，最大效率2．88lm/W，色度x＝0．31，y＝0．38（从4mA/cm^2到200mA/cm^2），半亮度寿命为2860小时（初始亮度1000cd/m^2）。比较了两种结构的器件，蓝红色发射在同一层结构的器件，在亮度、效率及稳定性上都优于蓝红发射在不同层结构的器件。     

联苯乙烯类蓝色发光材料DPVBi的合成及发光性质研究

合成了联苯乙烯类蓝色有机发光材料DPVBi[4，4′-二(2，2-二苯乙烯基)-1，l′-联苯]，用^1H-NMR，IR，元素分析等方法对其结构进行了表征。以DPVBi作发光层制备了电致发光器件，其结构为：ITO／CuPc／NPB／DPVBi/Alq3／LiF／Al，研究了器件的电致发光性质。器件最高亮度达4 373cd/cm^2，最大流明效率为1．24 lm／w，在20mA／cm^2电流密度驱动下的亮度为434cd／cm^2，CIE色坐标为x=0．15，y=0．16，器件的蓝色发光具有较好的色纯度。重点对器件发光色度的稳定性进行了研究，结果表明，随电流密度(4～4 000mA／cm^2)的变化，器件色度具有很好的稳定性。     

一种利用双发光区的有机红光电致发光器件

针对一般掺杂结构的红光有机电致发光器件效率随外加电压的增加而迅速下降。同时色度逐渐变差的特点,我们引入了在NPB层和Alq3层内同时掺杂DCJTB的具有双发光区的器件结构。制备的双发光区掺杂器件在驱动电压8—20V内发光效率只下降了4％;而色度从8V时的(x=0．6287,y=0．3663)变化到20V时的(x=0．6075,y=0．3841);器件的发光亮度从8V时的178cd／m^2变化到20V时的5962cd／m^2,具有较好的性能水平。观察到器件效率基本上不依赖于外加电压的变化而变化的特性,同时器件也保持一个比较好的色纯度,并对结果进行了分析。     

高稳定性的红色有机薄膜电致发光器件

有机薄膜电致发光作为新型的平板显示器件受到人们广泛的关注。有机发光器件研究的一个目标是发展全色显示。目前绿色和蓝色器件都实现了高亮度和长寿命。有关红色有机发光器件也有一些报道。如 Ｃ．Ｗ．Ｔａｎｇ等报道的 ＤＣＭ红光器件［１］,Ｊ．Ｋｉｄｏ［２］利用稀土有机物作为红色发射体,Ｐ．Ｅ．Ｂｕｒｒｏｕｓ报道的ＴＰＰ掺杂［３］Ｙ．Ｈａｍａｄａ报道的ＺｎＴＰＰ掺杂［４］, Ｍ． Ａ． Ｂａｌｄｏ利用ＰｔＯＥｐ［５］都得到红光。最近 Ｙ． Ｈａｍａｄａ报道利用ｒｕｂｒｅｎｅ作为辅助掺杂得到的红光器件色度不随电压的…     

基于CBP:BCzVB:Btp2Ir(acac)体系的白色有机电致发光器件色度飘移研究

以苯乙烯类化合物BCzVB为蓝色荧光染料,以铱配合物Btp_2Ir(acac)为红色磷光染料,共掺杂到CBP基质中作为发光层,制备了白色有机电致发光器件,研究了该体系发光色度漂移的原因。器件在掺杂CBP:6?zVB: 0．2%Btp_2Ir(acac),在．驱动电流从4～200 mA/cm~2变化范围内,发光色坐标从(0．340,0．273)飘移到(0．308, 0．273),色坐标轻微蓝移。对器件发光光谱和亮度-电流密度曲线等分析表明:器件色度的轻微蓝移是由于CBP基质向Btp_2Ir(acac)掺杂剂完全的能量传递、荧光染料BCzVB向磷光染料Btp_2Ir(acac)不完全的能量传递等内在物理过程和磷光染料Btp_2Ir(acac)自身发光饱和等特性共同决定的。     

色纯度改进的苯乙烯衍生物高效蓝色有机电致发光器件

以苯乙烯衍生物(amino-substituted distyryl arylene derivative，BCzVB)掺杂的4，4’-双(9-咔唑基)-1，1’-联苯(4，4’-N，N’-dicarbazole-biphyenyl，CBP)为发光层，制备了结构为ITO(indium tin oxide)／TPD(N，N’-diphenyl-N，N’-bis(3-methylphenyl)-1，1’biphenyl-4，4’diamine)／CBP：BCzVB／Alq3[tris-(8-hydroxy-quinolinato)aluminum)／Liq(8-hydroxy-quinolinato)lithium]／Al的电致发光器件。这里TPD、Alq3分别为空穴传输层和电子传输层，CBP：BCzVB为发光层，Liq为电子注入层。器件最高亮度为8500cd／m^2，效率为3．5cd／A(量子效率为2．6％)，器件色坐标[Commission Internationale de l’Eclairage(CIE)CO-ordinates]为x=0．15，y=0．16，与纯BCzVB作发光层的器件相比，器件的发光色纯度和效率得到大幅提高。光致发光与电致发光对比分析表明器件的发光主要来自能量传递和陷阱俘获机制，但陷阱俘获机制起了主导作用。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.     

Fiber Modal Index Measurements Based on Fiber Gratings

A novel method based on fiber gratings for measuring the effective indices of fiber modes is proposed. The effective index difference between the core mode and a cladding mode was obtained by analyzing the interference fringe of a pair of cascaded long-period fiber gratings. In order to extract the core mode index from the measured index difference, an index matching oil immersion method is proposed. By analyzing the interaction between the cladding mode and the oil applied on the cladding surface, the mode order and the effective index of the involved cladding mode might be calculated. Experimental results about the interference fringe shifts induced by the oil index and the oil-applied length are also presented.     

Optical Pulse Compression Schemes That Use Nonlinear Bragg Gratings

Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains.