Electroluminescent property of tetrakis(phenyl)porphyrin carbonyl ruthenium(Ⅱ)

Luminescent tetrakis(phenyl)porphyrin carbonyl ruthenium (Ⅱ) (RuTPPCO) complex was employed as a doped emitting material to fabricate red organic electroluminescent (EL) devices. The EL device structure was [ITO/copper phthalocyanine (Cu-Pc) (15.0 nm)/N,N′-di(α-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4, 4′-diamine (NPB)(60.0 nm)/tris(8-hydroxyquinolinato)aluminum (Alq3):RuTPPCO (50.0 nm)/LiF (1.0 nm)/Al (200.0 nm)]. The codeposited films of Alq3:RuTPPCO were utilized as the emitting layer to construct EL devices. Experimental results showed that energy transfer from Alq3 to RuTPPCO occurred in the codeposited films. The EL property of the codeposited Alq3:RuTPPCO films with different RuTPPCO concentrations was described. For the EL device with the RuTPPCO concentration of 15% by weight, deep red electroluminescence at 656 nm with the maximum EL efficiency of 0.32 cd/A was achieved.     

Spectral behavior of 8-hydroxyquinoline aluminum in nanometer-sized holes of porous alumina

The porous alumina have been prepared by anodization and an organic molecule 8-hydroxyquinoline aluminum (Alq₃) has been impregnated in the pores. The morphology measured through atomic force microscopy shows that the size of the pores is about 10 nm. A blue-shift photoluminescence of Alq₃ in nanometer-sized hole is close to that of the monomers. The measured spectral characteristics demonstrate the limitation of the porous alumina to the emission of Alq₃.     

Synthesis, structure, optoelectronic properties of novel zinc Schiff-base complexes

Two novel zinc Schiff-base complexes, bis-(N-(2-hydroxybenzidene)-p-aminodimethylaniline)zinc(II) (2) and bis-(N-(2-hydroxy-1-naphthidene)-p-aminodimethylaniline)zinc(II) (4) were designed and synthesized. Both the complexes exhibit good solubility in organic solvents and excellent thermal stabilities. A single crystal of 2 was grown and its crystalline structure was determined from X-ray diffraction data. Analysis of the electronic structures of both the zinc complexes calculated by density functional theory reveals a localization of orbital. The UV-Vis absorption and photoluminescence profiles of 4 in thin film are similar to those of 2, but the emission for 4 is red-shifted compared to 2. Three-layered devices with a configuration of ITO/NPB/2/Alq 3 /LiF/Al and ITO/NPB/4/Alq 3 /LiF/Al show a yellow and red emission, respectively.     

压电悬臂梁式微型电场传感器的设计与制备

提出并研制一种新型压电悬臂梁式微型电场传感器,该传感器是基于压电(PZT)薄膜驱动的悬臂梁式微型电场传感器;同时介绍了传感器的工作原理、结构设计、制作工艺以及初步测试结果。该微型电场传感器由多根压电悬臂梁构成,每根悬臂梁能同时具有屏蔽电场和感应电荷功能。对传感器感应电荷的能力进行了计算;并根据计算结果和工艺要求设计了传感器的参数。该微型电场传感器采用微加工技术制作,每根悬臂梁为多层复合结构(Al/Si3N4/Pt/PZT/Pt/Ti/Si O2/Si),其中PZT薄膜采用溶胶-凝胶法制备。测试结果证明,传感器具有良好的响应特性。     

4H-SiC MOS电容栅介质经NO退火电流导通机理研究

本文对进行NO退火和非NO退火的SiC MOS电容的栅泄漏电流的导通机理进行了分析,研究表明在高场下经过NO退火和未经过NO退火的样品的栅泄露电流都由Fowler-Nordheim （FN）隧穿决定,经过NO退火的势垒高度为2.67 eV,而未经过NO退火的样品势垒高度为2.54 eV,势垒高度的增加说明了氮化的作用.在中度电场区域,通过拟合分析发现此区域的栅泄漏电流主要由Poole-Frenkel发射（PF）决定,并不受陷阱辅助隧穿trap assisted tunneling（TAT）的影响.同时C-V特性也明显看出NO退火对界面质量的影响.      

新型顶发射有机电致白光二极管的研究

为了提高顶发射白光有机发光二极管(top-emitting white organic light-emitting diodes,TWOLEDs)色谱稳定性，对一种拥有Ag反射镜的新型双蓝光发光单元顶发射器件展开研究，发现结构为Ag/Glass/ITO/MoO₃(5nm)/TAPC(30nm)/TCTA(5nm)/Firpic:TCTA(10%,20nm)/Firpic:TmPyPb(10%,10nm)TPBi(30nm)/LiF(1nm)/Al(0.8nm)/Ag(22nm)/Alq₃(50nm)的蓝光器件具有最佳光电性能，其最高电流效率可以达到9.76cd·A^-1。基于该结构，结合DCJTB荧光染料制备的颜色转换层实现顶发射白光器件。结果表明，当颜色转换层DCJTB浓度为2.5%时，获得了电流效率为2.45cd·A^-1，CIE色坐标为(0.338,0.337)以及显色指数CRI为72的TWOLEDs，器件微腔效应较弱且光谱随电流密度与观测角度改变仅有微弱变化。     

Improving the efficiency of organic photovoltaic cells by introducing an ultrathin modification layer with a strong dipole moment

A method to improve the efficiency of organic photovoltaic cells through inclusion of an ultrathin modification layer of Al2O3 or LiF sandwiched between poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid(PEDOT:PSS) and indium tin oxide layers is developed.Because of the strong dipole moments of LiF and Al2O3,either can enhance the built-in electric field,which increases the probability of the carriers reaching the corresponding electrode.In addition,the low work function of PEDOT:PSS can decrease the energy barrier for carrier transmission.A 21.7% improvement in the power conversion efficiency of experimental devices was achieved,mainly because the short circuit current was enhanced by almost 30%.     

Red organic light emitting device with improved performance using a novel fluorescent dye codoped with phosphor-sensitizer

Efficient red organic light-emitting device consisted of a compound fluorescent-phosphor-sensitized emission layer was fabricated. A novel red fluorescent dye, 3-(dicyanomethylene)-5,5-dimethyl-1-(4-dimethylamino-styryl) cyclohexene (DCDDC), and a green phosphorescent dye, fac tris(2-phenylpyridine) iridium [Ir(ppy)3] were codoped into a host material 4,4’-N,N’-dicarbazolebiphenyl (CBP). By adjusting the component ratio of doping system, a series of devices with different concentration proportion of Ir(ppy)3:DCDDC were constructed. The results demonstrated that the device with 0.2 wt% DCDDC had a maximum power efficiency (η_p) of 2.12 lm/W at a current density of 0.1 mA/cm², which was about 38% higher than that of conventional fluorescent device. When at a current density of 4 mA/cm2 (100 cd/m²) and 52 mA/cm² (1000 cd/m²), the η_p percentage was about 160% and 143% higher than that of conventional device, respectively. A stable red light emission at a peak of 615 nm with Commissions Internationale de l’Eclairage coordinates near the region of (0.56, 0.42) in a wide bias range was also obtained. The improved performances were attributed to the efficient multiple-stage energy transfer from the host to the guest and the suppression of loss mechanism.     

利用瞬态电致发光研究有机小分子发光器件中延迟荧光的发射机理

制备了两种基于Alq3的有机小分子发光器件,其结构分别为:ITO/NPB/Alq3/LiF/Al和ITO/NPB/Alq3:DCM/Alq3/LiF/Al.利用瞬态电致发光技术,研究了这两种发光器件中延迟荧光的发射机理.发现在Alq3的双层器件中,延迟荧光较弱,且主要是由电荷延迟注入所形成的单重态激子退激产生;而在Alq3:DCM染料掺杂器件中,延迟荧光较强.通过分析Alq3:DCM掺杂器件的延迟荧光对反偏压和脉冲偏压脉宽的依赖关系,进一步发现掺杂器件的延迟荧光主要来自于发光层中受陷电荷释放后的再复合过程以及DCM客体分子中的三重态-三重态激子淬灭(Triplet-Triplet Annihilation,TTA)过程.其中,TTA过程是Alq3:DCM掺杂器件中延迟荧光产生的主要机制.     

基底偏压对氮化硼薄膜场发射特性的影响

利用射频磁控溅射方法, 在n型（100）Si（0.008～0.02 Ω·m）基底上沉积了氮化 硼（BN）薄膜. 红外光谱分析表明, BN薄膜结构均为六角BN（h-BN）相. 在超高真空系统中 测量了BN薄膜的场发射特性, 发现BN薄膜的场发射特性与基底偏压关系很大, 阈值电场随基 底偏压的增加先增加后减小. 基底偏压为-140 V时BN薄膜样品场发射特性要好于其他样品, 阈值电场低于8 V/μm. F~N曲线表明, 在外加电场的作用下, 电子隧穿BN薄膜表面势垒发射 到真空.     

合金碳化物(Fe,Mo)_3C的磁性及磁致热力学性质

利用基于第一性原理的VASP软件计算钢中合金碳化物(Fe,Mo)_3C在0 K、0 Pa的磁矩和形成能,利用热力学平衡软件MTDATA计算合金碳化物(Fe,Mo)_3C的化学自由能改变量,利用Weiss分子场理论计算合金碳化物在12 T强磁场下的磁自由能改变量。结果表明,合金碳化物(Fe,Mo)_3C的磁矩主要来源于不同Wyckoff位置的Fe原子,8d位置的Fe原子对磁矩的影响比4c位置的Fe原子更大,而Mo原子会使合金碳化物的磁矩降低;合金碳化物Fe_2MoC、Mo_3C的形成能为负,表明这两种合金碳化物比Fe_3C和FeMo_2C更稳定;另外,Mo原子会降低合金碳化物(Fe,Mo)_3C化学自由能改变量,增大其磁自由能改变量。     

有机共轭聚合物材料中的齐纳隧穿

基于扩展的SSH模型,采用非绝热动力学方法,研究高电场下一维有机共轭聚合物的电性质.发现在足够高的电场下,价带中的电子可以穿过带隙进入导带,即有机聚合物中的齐纳隧穿现象.伴随电子的带间隧穿,带隙消失,发生从绝缘体(半导体)到金属的相变(I-M 相变),晶格结构同时发生重大变化.     

Investigation of the effects of MoO_3 buffer layer on charge carrier injection and extraction by capacitance–voltage measurement

The effects of MoO3thin buffer layer on charge carrier injection and extraction in inverted configuration ITO/ZnO/MEH-PPV(poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene))/MoO3(0,5 nm)/Ag hybrid solar cells are investigated by capacitance–voltage measurement under dark and light illumination conditions.The efficiency of charge carrier injection and extraction is enhanced by inserting 5 nm MoO3thin layer,resulting in better device performances.Charge carrier transport of the whole device is improved and the interface energy barrier is reduced by inserting 5 nm MoO3thin buffer layer.The device fill factor is increased from 54.1%to 57.5%after modifying 5 nm MoO3.Simulations and experimental results consistently show that in the forward voltage under dark,the device with the 5 nm MoO3thin layer modification generates larger value of capacitance than the device without MoO3layer.While under illumination,the device with the 5 nm MoO3layer generates smaller value of capacitance than the device without the 5 nm MoO3layer in the bias region of reverse and before the peak position of maximum capacitance(VCmax).The underlying mechanism of the MoO3anode buffer layer on device current density–voltage characteristics is discussed.     

Simple method to rapidly fabricate chain-like carbon nanotube films and its field emission properties

A simple process to fabricate chain-like carbon nanotube (CNT) films by microwave plasma-enhanced chemical vapor deposition (MPCVD) was developed successfully. Prior to deposition, the Ti/Al₂O₃ substrates were ground with Fe-doped SiO₂ powder. The nano-structure of the deposited films was analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. The field electron emission characteristics of the chain-like carbon nanotube films were measured under the vacuum of 10-5 Pa. The low turn-on field of 0.80 V/μm and the emission current density of 8.5 mA/cm2 at the electric field of 3.0 V/μm are obtained. Based on the above results, chain-like carbon nanotube films probably have important applications in cold cathode materials and electrode materials.     

Electronic structures and nonlinear optical properties of XAuPH<Subscript>3</Subscript>

The studies on model systems XAuPH3(X-H,F,Cl,Br,I,CN,CH3)have been carried out by using ab intiol HF and DFT B3LYP methods at pseudopotential and double-zeta LANL2DZ level.The results are compared with those of MP2,The properties of the models.i.e.the atomic net charge populations.the frontier molecular orbitals and nonlinear optical(NLO)properties have been investigated under an applied electric field on the basis of optimized structures.The computational results show that for these models characterized as electron acceptor-metal-electron donor(A-M-D)system,the NLO properties are due to intramolecular charge-transfer interaction between the acceptor and the donor.The more charges transfer gives,the better NLO properties.In the selected model systems,IAuPH3 has the biggest βvec and γof 1184.1942 a.u.and 17341.9214 a.u.,whereas IC6H4PH3^ ,A TYPICAL a-π-D organic conjugated system,has βvec and γof 710.7697 and 11664.1405 a.u.respectively.In comparison.IAuPH3 has significant NLO properties.     

Study on delayed cracking of conductive notch under electric field in PZT-5H ferroelectric ceramics

Internal electrodes have widely been adopted in electronic and electromechanical devices made of ferroelectric ceramics. There embedded electrodes naturally function as a pre-conductive notch, which lead to the failure of the devices under electric and/or…     

Pulse width effect on the dissociation probability of CH4^＋ in the intense femtosecond laser field

The electric field strength of the intense ultrashort laser pulse can reach or exceed 108 V/cm, the intensity of the Coulomb field responsible for the stability of molecules. Exposed to such intense laser fields, mole- cules become unstable, undergoing di…     

外电场下SDB基本单元的氢氚取代的热力学研究

采用密度泛函B3P86方法在6-311G基组水平上对聚苯乙烯-二乙烯基苯(Polystyrene-Divinylbenzene SDB)单元结构分子在外场下的结构进行优化。根据热力学原理,研究了外场下SDB分子的氢氚取代反应的热力学性质,计算得到外场下SDB单元结构氢氚取代反应在不同温度下的标准生成自由能函变、反应平衡常数及氢氚反应的平衡压力比。表明T_2(g)+SDB_((H2))(s)→H_2(g)+SDB_((T2))(s)氢氚取代反应随外场的增加,在反应热力学上有利于正向反应的进行。     

气体绝缘363 kV快速真空断路器电场分析

具有快速开断能力的真空断路器能够在极短时间内开断短路电流,有利于减小短路电流对电网设备的冲击,但目前单断口的真空断路器难以直接应用于高电压等级电网。提出了一种全新的SF6气体绝缘的363kV真空断路器,采用40.5kV真空灭弧室的串并联结构,采用基于涡流驱动原理的操动机构实现短路电流的快速开断。对于高电压等级真空断路器,需要重点研究断路器内部的电场分布问题。基于总体设计结构的对称性对断路器单个单元和端部单元进行了简化,然后建立了对应的断路器三维多重介质有限元计算模型,分析了导电杆、灭弧室、接线端子等关键部件的电场强度。计算结果表明:电场严重集中于上下接线端子、转接法兰的圆角处。雷电冲击电压下,接线端子圆角和转接法兰圆角最大值分别为28.5kV/mm和22.9kV/mm,导电杆的表面最大电场为13.4kV/mm,真空灭弧室内外及其他部件均处于控制范围内。对接线端子的圆角半径进行了优化设计,确定其圆角半径为12mm,为样机的生产提供了参考。     

沸石咪唑骨架衍生空心纳米电极材料可控制备及其电化学性能研究

超级电容器是介于可充电电池和传统电容器之间的一种新型储能器件。它具有高功率密度、快速充放电和环境友好等优点。在众多应用于超级电容器的电极材料中,金属有机骨架材料因具有大的比表面积,可灵活调控的组成和结构,是十分理想的电极材料之一,又由于其易于合成、独特的结构和反应特性,也是制备纳米结构电极材料的理想模板之一。以沸石咪唑骨架（zeolitic lmidazolate framework,ZIF）-67为前驱体,采用二水合钼酸钠盐溶液刻蚀的方法成功制备了空心CoMo 层状双金属氢氧化物（layered double hydroxides, LDH）纳米笼结构,同时还讨论了钼酸钠的用量对最终产物形貌和性能的影响。当用作超级电容器电极材料时,所制备的空心Co₁Mo₅ LDH在1 A/g的时候最多可提供578 F/g的比电容,当电流密度增加到10 A/g时,比电容保持在346 F/g。与活性炭组装成非对称超级电容器后,该储能器件在功率密度750 W/kg时,能量密度最大可达到21.25 W·h/kg。在5 A/g的电流密度下,经过15 000次充放电循环后,仍保持了90%的初始容量。