利用LiF/Al作为电极的有机电致发光器件

本文报道了利用LiF/Al作为负电极的有机电致发光器件,器件结构为ITO/TPD/Alq3/LiF/Al,LiF层的加入增强了电子注入,当其厚度为0.4nm时,器件的性能最好,与单层Al和Mg/Al电极的同类器件相比,此时器件的开启电压由Al电极时的4.3V和Mg/Al电极时的3.0V降低到了2.0V,器件的最大亮度分别由4000cd/m²、14000cd/m²提高到19600cd/m²,器件的发光效率也分别增加了5倍和2倍,达到2.66lm/W.     

Temperature-dependent electrical properties of organic light-emitting diodes depending on cathodes

We have studied temperature-dependent electrical properties of organic light-emitting diodes with a variation of cathode materials; Al, LiAl, and LiF/Al. The organic light-emitting diodes emit a light by a recombination of injected charge carriers such as holes and electrons. Thus, the charge transport is affected by the injection barrier at the interface. By varying the cathode materials, the electron injection at the interface could be controlled because of the work-function change at the cathode. Temperature-dependent current–voltage luminance characteristics of the organic light-emitting diodes were measured in the temperature range from 10 to 300 K. The current-voltage characteristics were analyzed in terms of Fowler–Nordheim tunneling model, and the energy-barrier height was obtained. A measured lifetime of device with LiF/Al cathode is relatively longer than the other cathodes at room temperature: 4.5 h for Al cathode, 12.4 h for LiAl, and 29.6 h for LiF/Al. The device with LiAl and LiF/Al cathode, in the aspect of lifetime and luminous efficiency, is superior to one of other cathodes.     

Improved performance and stability by an Al/Ni bilayer cathode in organic light-emitting diodes

Al/Ni bilayer cathode was used to improve the electroluminescent (EL) efficiency and stability in N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′ biphenyl 4,4′-dimaine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq₃)-based organic light-emitting diodes. The device with LiF/Al/Ni cathode achieved a maximum power efficiency of 2.8 lm/W at current density of 1.2 mA/cm², which is 1.4 times the efficiency of device with the state-of-the-art LiF/Al cathode. Importantly, the device stability was significantly enhanced due to the utilization of LiF/Al/Ni cathode. The lifetime at 30% decay in luminance for LiF/Al/Ni cathode was extrapolated to 400 h at an initial luminance of 100 cd/m², which is 10 times better than the LiF/Al cathode.     

复合阴极Ag/LiF/Al对P3HT:PCBM太阳能电池性能的影响

在P3HT∶PCBM聚合物太阳能电池的阴极LiF/Al中引入纳米结构的银膜组成Ag/LiF/Al复合阴极,太阳能电池的光电流能显著提高。在AM1.5G和100mW.cm-2的模拟太阳光照射下,当银膜厚度为4纳米时,优化的太阳能电池的光电流要比只有LiF/Al的参比太阳能电池高20%以上。研究表明,纳米银膜产生的表面等离子体效应是增强聚合物太阳能电池光电池的主要原因。不过,银膜修饰的太阳能电池填充因子和开路电压要比参考电池低,最终使该类型电池效率降低。在银膜处增加的载流子复合可能是导致电池填充因子、开路电压和能量转化效率降低的重要原因。     

基于Pb和LiF复合阴极的高对比度有机电致发光器件

通过氟化锂和铅共蒸,做成金属-绝缘体复合阴极,降低了阴极反射率,进而实现了高对比度有机电致发光器件(OLED)。对该高对比度器件的光学反射特性和电学特性进行了研究,并与传统的金属铝/氟化锂阴极器件进行了比较。该铅-氟化锂复合阴极的反射率只有18%,比相同厚度铝阴极的反射率降低了大约5倍,另外,该高对比度器件的电致发光特性与传统器件大致相当。     

CsF/Al阴极对提高芴基饱和红光器件性能的研究

从聚合物/电极界面修饰的角度对基于饱和红光聚合物PFO-SeBT(9,9-二辛基芴与4,7-二硒吩-2,1,3-苯并噻二唑的无规共聚物)的发光二极管的性能进行了改进，通过采用CsF/Al阴极并优化CsF的厚度以及在PFO-SeBT1/阳极界面插入聚乙烯基咔唑(PVK)层，使器件的最大电致发光外量子效率达到1.79%，比采用低功函数的金属Ba/Al阴极器件的效率提高了两倍多.器件的性能得以改善的原因是CsF/Al阴极能有效提高电子注入能力以及PVK层对电子的阻挡作用. 关键词： 聚合物发光二极管 聚合物/电极界面 CsF/Al阴极 电子注入     

Effect of Ca interlayer thickness on electron injection of lithium quinolate/Ca/Al cathodes

Electron injection behavior of lithium quinolate (Liq)/Ca/Al cathode was investigated by using X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy (UPS). Interfacial energy barrier lowering of Liq/Ca/Al cathode was dependent on Ca thickness and maximum energy level shift was observed at a Ca thickness of 1 nm. Maximum current density could be obtained in Liq/Ca/Al device at a Ca thickness of 1 nm and it was well correlated with energy level shift from UPS measurement. Power efficiency of Liq/Al device could be improved by more than 70% by inserting Ca layer between Liq and Al.     

A study of the degradation of poly(3-octylthiophene)-based light emitting diodes by Surface Enhanced Raman Scattering

Organic light emitting diodes (OLED) based on poly(3-octylthiophene) (P3OT) were studied by on-line Surface Enhanced Raman Scattering (SERS) experiments. A simultaneous reduction of the emitted power and an increase of the SERS signal was observed above an 8 V bias voltage in the case of ITO/P3OT/Al structures. On-line measurements of the temperature and independent tests with an atomic force microscope, performed on the Al cathode before and after current flow, demonstrated that the observed enhancement of the Raman signal was partly thermal and partly electromagnetic in origin, with clear evidence of cathode roughening induced by current flow. In contrast, analogous tests performed on P3OT-based OLEDs containing a composite Al+Ag cathode showed that the breakdown was related to electrode delamination. PACS 78.60Fi; 78.30Jw; 85.60Jb     

氯化铯甲醇溶液对有机聚合物太阳能电池的影响

研究了氯化铯的甲醇溶液作为阴极修饰层,来提高传统有机聚合物太阳能电池器件性能。通过电容-电压(C-V)测试分析了铝电极和PTB7/PC_(70)BM之间的界面电荷积累情况,同时测试了紫外光电子能谱(UPS),对铝的功函数改变作了研究。结果表明,采用氯化铯的甲醇溶液作阴极修饰层的器件,其短路电流(J_(sc))、开路电压(V_(oc))、填充因子(FF)都有所提高,光电转化效率达到6.36%,与仅用甲醇处理过的器件相比,光电转化效率提高了11%;与未经甲醇处理的器件相比,光电转化效率提高了42.6%。这种一步溶液处理法能够减少电荷积累,同时降低铝电极的功函数,利于电子收集,进而提高器件性能。     

倒置器件结构及局域等离子体效应对CdSe量子点LED发光性能的改进

研究了倒置器件结构以及CdSe量子点发光材料与金属纳米粒子之间的相互作用对量子点的电致发光性能的影响。利用TiO₂作为电子传输/注入层,成功地制备了倒置结构的量子点电致发光器件。通过对单载流子器件电压-电流特性的分析,证明了ITO作为阴极到TiO₂的电子注入特性与Al作为阴极时的效果几乎相同。观察到金属纳米粒子产生的局域等离子体效应提高了器件的效率,使得效率随电流增大而降低的速度明显减小。在电流密度为200 mA/cm²时,电致发光器件的效率大约提高了42%。     

在横向磁场中真空电弧后退速度和阴极温度的关系

本文用光学方法测定了在横向磁场中真空电弧后退运动的速度和阴极温度的关系。实验发现,随着阴极温度的增加,电弧的后退速度下降。实验测得的后退速度的温度关系可用真空电弧后退运动的正离子喷流模型加以解释。 关键词：     

磷酸酯聚芴阴极界面修饰层对聚合物电致发光性能的影响

发展了基于稳定金属电极的阴极界面材料,对促进聚合物电致发光器件的产业化进程具有重要意义。侧链含磷酸酯功能基团的聚芴衍生物（PF-EP）是一种极性聚合物中性材料,能溶于乙醇等醇类溶剂,非常适合制备多层溶液加工型发光器件。除此之外,它结合稳定的金属Al电极能实现有效电子注入。本文以PF-EP在绿光聚芴发光器件中的应用为例,详细对比分析了两种基于PF-EP的阴极电极结构（PF-EP/LiF/Al和PF-EP/Al）的器件EL性能。结果显示,PF-EP/LiF/Al阴极结构具有更优异的电子注入能力。基于单电子器件和X射线光电子能谱,本文对这一高效电子注入结构的注入能力和注入机理进行了探讨。     

Cs_2CO_3共蒸阴极对有机电致发光器件性能的影响(英文)

研究了碳酸铯(Cs2CO3)掺杂8-羟基喹啉铝(Alq3)作为电子注入层对有机电致发光器件性能的影响。结果表明,与常用的Cs2CO3超薄层作电子注入层相比,Cs2CO3∶Alq3共蒸阴极对器件效率和亮度有很大提高,器件电流效率从3.1 cd/A(Cs2CO31 nm/Al)提高到6.5 cd/A(Cs2CO33%∶Alq3/Al)。器件性能的提高归因于Cs2CO3∶Alq3共蒸阴极比单层Cs2CO3阴极具有更好的电子注入能力和电子传输性能。薄膜形貌表明,共蒸阴极能有效降低Alq3表面粗糙度,有助于提高器件发光性能及寿命。     

NaCl/Ca/Al as an efficient cathode in organic light-emitting devices

An efficient cathode NaCl/Ca/Al used to improve the performance of organic light-emitting devices (OLEDs) was reported. Standard N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′ biphenyl 4,4′-dimaine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq₃) devices with NaCl/Ca/Al cathode showed dramatically enhanced electroluminescent (EL) efficiency. A power efficiency of 4.6 lm/W was obtained for OLEDs with 2 nm of NaCl and 10 nm of Ca, which is much higher than 2.0 lm/W, 3.1 lm/W, 2.1 lm/W and 3.6 lm/W in devices using, respectively, the LiF (1 nm)/Al, LiF (1 nm)/Ca (10 nm)/Al, Ca (10 nm)/Al and NaCl (2 nm)/Al cathodes. The investigation of the electron injection in electron-only devices indicates that the utilization of the NaCl/Ca/Al cathode substantially enhances the electron injection current, which in case of OLEDs leads to the improvement of the brightness and efficiency.     

PTCBI作为阴极修饰层对Rubrene/C70器件性能的影响

制备了结构为ITO/MoO₃(6 nm)/Rubrene (30 nm)/C₇₀ (30 nm)/PTCBI(x nm)/Al (150 nm)器件, 研究了四羧基苝的衍生物PTCBI作为阴极修饰层对Rubrene/C₇₀有机太阳能电池的作用. 实验结果显示, 在C₇₀与Al电极之间插入PTCBI 后, 电池性能得到明显改善; 分析表明, 插入PTCBI后, 活性层与阴极形成了良好的欧姆接触, 提高了器件的内建电场, 同时PTCBI避免了激子与Al电极的接触, 减少了在制备过程中高动能Al对C₇₀的破坏. 进一步考察了PTCBI厚度对电池的性能的影响, 结果显示, 厚度为6 nm的PTCBI 层器件性能最佳, 其开路电压(V_OC)、填充因子(FF)、短路电流密度(J_SC)与功率转换效率(ηP)与未插入PTCBI修饰层的器件相比分别提高了70.4%, 55.5%, 125.1%, 292.2%. 当PTCBI的厚度大于6 nm时, 激子解离后产生的自由电子会在PTCBI与阴极界面积累, 导致器件J-V曲线出现S形.     

聚乙烯-碘化铯中子阴极的最佳化

本文的中子阴级由聚乙烯、导电基底(Al)和碘化铯二次电子发射体组成.文中建立了一个此中子阴级的新的物理模型,并采用Monte Carlo方法模拟了中子同阴极作用产生低能二次电子的物理过程.模拟得到的出射二次电子能谱和产额与实验结果和理论分析符合得较好.我们还得到了最大探测效率时各中子阴极组分的最佳厚度.     

一种采用Li3N掺杂电子注入层的底发射倒置结构OLED的制备

采用Li3N掺杂电子注入层Alq3∶Li3N,制作了一种结构为ITO/Alq3 Alq3∶Li3N/Alq3/NPB/MoO3/Al的倒置底发射有机发光器件.其中ITO玻璃作为透明阴极,金属Al作为顶部阳极,在ITO阴极与电子传输层之间加入Li3N n型掺杂层,改善了该器件的电子注入和传输能力|在Al阳极与空穴传输层之间加入MoO3缓冲层,降低了Al阳极与NPB之间较大的空穴注入势垒,改善了空穴注入能力.实验表明:此结构的倒置底发射有机发光器件性能可达到传统结构的常用有机发光器件如ITO/NPB/Alq3/LiF/Al的性能,完全可以满足非晶硅薄膜晶体管有源有机发光器件中驱动电路的匹配及性能要求.     

ПОВЕДЕНИЕ КАТОДНЫХ П ЯТЕН В СИЛЬНОТОЧНОМ ЭЛЕКТРИЧЕСКОМ РАЗРЯ ДЕ

A magnetooptical rapid-action shutter was used to study the formation of cathode spots on the electrodes of a short-time high-intensity electric discharge. It was found that there exist two types of cathode spots. Spots of the first type are transported with a high velocity to the cathode surface not yet reached by the discharge. Spots of the second type, on the other hand, move in the neighbourhood of the centre of evaporation. On metals which evaporate with difficulty (Ni, Cu, Al) only spots of the first type may exist. On metals which easily evaporate (Cd, Sn, Zn) spots of both types exist simultaneously. The formation of cathode spots is explained by means of the cold emission of electrons from the cathode.     

Effect of alumina additions in YSZ on the microstructure and degradation of the LSM–YSZ interface

The cathode–electrolyte interface in a solid oxide fuel cell is examined to understand why premature delamination is observed in alumina substituted YSZ electrolyte. From XRD, SEM and TEM observations it was concluded that after high temperature sintering a tetragonal (Mn,Al)₃O₄ forms at the interface, which during prolonged fuel cell operation forms a cubic (Mn,Al)₃O₄ phase. This transformation is associated with volume decrease creating voids which ultimately weaken the cathode–electrolyte interface sufficiently for the cathode layer to delaminate off the YSZ–Al₂O₃ electrolyte.     

Enhanced electron field emission characteristics of single-walled carbon nanotube films by ultrasonic bonding

A novel ultrasonic bonding process was used to fabricate the electron field emission cathode of single-walled nanotube film, which was deposited on an Al plate substrate by electrophoretic deposition. Electron field emission properties were improved remarkably after the cathode carbon nanotubes nanobonded with the Al substrate. Turn-on voltage showed a significant decrease and the emission current was much stabilized. This can be attributed to the reduction of the contact resistance in bonding area and easily moving electrons for field emission after ultrasonic bonding. In addition, the field emission performances of SWCNTs films formed at different bonding conditions were also studied. With a simple nano-bonding apparatus, this technique has low cost, and can be utilized for extensively roboticized fabrication of high performance field emission cathodes with short process time.