Zn(BTZ)2白色有机电致发光材料的合成及其器件制备

以PCl₃为脱水剂,将邻氨基硫酚与水杨酸脱水环化合成出2-(2-羟基苯基)苯并噻唑,并进一步将所得产物与乙酸锌反应合成出2-(2-羟基苯基)苯并噻唑螯合锌(Zn(BTZ)₂)材料。以该配合物作为发光层制备出结构为ITO/PVK:TPD/Zn(BTZ)₂/Al近白色电致发光器件,其色坐标位于白场之内(x=0.242,y=0.359),在驱动电压为16V时,亮度达3200cdm²,对应的量子效率为0.32%。进一步在Zn(BTZ)₂中掺入橙红色染料Rubrene,制成ITO/PVK:TPD/Zn(BTZ)₂:Rubrene/Al结构器件,实现了纯白色发光(色坐标值:x=0.324,y=0.343),非常接近于白色等能点,且量子效率达0.47%。最后对上述器件的发光和电学性能进行了深入的研究和探讨。     

蓝色发光材料DPVBi掺杂DCJTB发光性质的研究

对蓝光材料DPVBi掺杂红光染料DCJTB的发光性质进行了研究。首先研究了DPVBi掺杂不同质量浓度DCJTB的光致发光，当掺杂质量浓度为0.1％时，光致发光得到白光(色度x=0．36，y=0．34)。基于光致发光的实验结果，以DPVBi掺杂不同质量浓度DCJTB作发光层，制备了结构为ITO／CuPc／NPB／DPVBi：DCJTB/Alq3／LiF／Al的器件，当掺杂质量浓度为0．08％时器件实现了白色发光(色度为x=0．25，y=0．32)。研究了该白光器件的电致发光性质，白光器件在14V时达到最高亮度7822cd／m^2。在20mA／cm^2电流密度驱动下的亮度为489cd/m^2，最大流明效率为1．75lm／W。     

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。     

稳定的蓝色及白色有机薄膜电致发光器件

报道了一种稳定的蓝色和白色有机薄膜电致发光器件,蓝色器件最大亮度为7526cd／m^2,最大效率1．451m／W,半亮度寿命1035h(初始亮度l00cd／m^2)。白色器件的最大亮度为14850cd／m^2,最大效率2．881m／W,色度x=0．31,y=0．38,且色度不随电流增大而变化,半亮度寿命为2860h(初始亮度100cd／m^2)。     

不同电极对蓝光有机电致发光器件性能的影响

利用高真空多源型有机分子沉积系统分别制备了不同负电极为Al、LiF/Al和Mg:Ag的有机小分子多层电致发光器件,比较了不同负极对以五苯基环戊二烯（PPCP）为发光层的蓝光有机电致发光器件性能的影响,发现以LiF/Al作负极的器件在综合性能上优于其它器件。其中器件ITO／TPD／PPDP／Alq/LiF/Al蓝光发射的最大发光亮度达2375cd/m^2,最大发光效率为0.26lm/W.     

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。     

以联苯乙烯衍生物为发光层的蓝色有机发光二极管特性的研究

以一种新型联苯乙烯衍生物NPVBi作为发光层，制备了结构为：ITO／TPD／NPVBi/Alq3/LiF/Al的有机薄膜电致发光器件，其中TPD厚度保持为50nm,NPVBi与Alq3厚度之和保持为50nm。通过调节NPVBi与Alq3的厚度，获得了色纯度较好的NPVBi蓝色电致发光，最高亮度为708cd/m^2，最大流明效率为1.13lm/W。结果表明，发光层NPVBi和电子传输层Alq3的厚度对器件的发光特性有显著的影响。     

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。     

一种白光有机电致发光器件的制备

通过对器件结构的优化设计，提高了白光电致发光器件中蓝光成分的发光效率，从而得到了一种较为理想的有机白光电致发光器件。驱动电压为5V时，电流密度J=0．5mA／cm^2，器件的效率达到最大，流明效率为1．92 lm／W，此时器件的发光亮度接近20cd／m^2。色坐标为(x=O．317，y=0．328)。非常接近白光等能点．是色度很好的白光。并且在很大范围内，色度随器件的驱动电压或电流变化不大，当驱动电压变化至15V时。f=232mA／cm^2，色坐标变化至(x=0．338，y=O．353)。在电压为22V时，器件的亮度达到最大，为17 000cd／m^2。此外器件结构相对简单。器件制备的可重复性得到很大程度的改善。     

红色有机发光二极管

制备了以芳香族二胺类衍生物TPD为空穴传输层、8－羟基喹啉铝Alq3掺杂红光染料DCJTB作为发光层LiF/Al为复合电极的红色发光二极管。研究了不同掺杂质量分数对器件发光光谱、亮度电流电压特性的影响。发现由于DCJTB的自极化作用,发光峰值位置有30nm的移动,当掺杂质量分数为0.2％和3％时,器件的最高亮度分别为17400cd/m^2和2900cd/m^2,20mA/cm^2时其亮度又分别为1080cd/m^2和150cd/m^2,量子效率分别为2％和0.5％。     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.