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1.
用光伏效应研究有机薄膜电致发光器件中的接触性质 总被引:2,自引:0,他引:2
首次发现了有机薄膜电致发光器件的光生伏特效应,通过对器件的光电流响应谱的详细研究,分析了不同结构的有机发光器件中的有机半导体之间,以及有机半导体与电极材料之间的半导体接触性质,发现有机发光材料Alq3,有机空穴传输材料daimine与金属铝电极之间形成阻挡接触,是电致发光器件发光和产生光电效应的根本原因;而双层器件中有机层Alq3与diamine之间的结是双层器件产生高发光效率的原因,正是这种结在双层器件中起了局限载流子和激子的作用,使发光亮度大为提高,结合分区掺杂实验结果,给出了较完善的能带模型. 相似文献
2.
用光伏效应研究有机薄膜电致发光器件中的接触性质 总被引:1,自引:0,他引:1
首次发现了有机薄膜电致发光器件的光生伏特效应,通过对器件的光电流响应谱的详细研究,分析了不同结构的有机发光器件中的有机半导体之间,以及有机半导体与电极材料之间的半导体接触性质,发现有机发光材料Alq3,有机空穴传输材料daimine与金属铝电极之间形成阻挡接触,是电致发光器件发光和产生光电效应的根本原因,而双层器件中有机层Alq3与diamine之间的结是双层器件产生高发光效率的原因,正是这种结在双层器件中起了局限载流子和激子的作用,使发光亮度大为提高,结合分区掺杂实验结果,给出了较完善的能带模型。 相似文献
3.
Fuchs GD Katine JA Kiselev SI Mauri D Wooley KS Ralph DC Buhrman RA 《Physical review letters》2006,96(18):186603
We employ the spin-torque response of magnetic tunnel junctions with ultrathin MgO tunnel barrier layers to investigate the relationship between spin transfer and tunnel magnetoresistance (TMR) under finite bias, and find that the spin torque per unit current exerted on the free layer decreases by < 10% over a bias range where the TMR decreases by > 40%. This is inconsistent with free-electron-like spin-polarized tunneling and reduced-surface-magnetism models of the TMR bias dependence, but is consistent with magnetic-state-dependent decay lengths in the tunnel barrier. 相似文献
4.
Two types of organic light-emitting diodes with structures of ITO/N,N'-bis(1-naphthyl)-N,N'-diphenyl,1,1'-biphenyl-4,4'-diamine (NPB)/tris(8-hydroquinolinato)aluminum(Alq 3)/2,9-dimethyl-4,7-diphenyl-l,10-phenanthroline(BCP)/Alq 3:4-dicyanomethylene-2-(tert-butyl)-6-methyl-4H-pyran(DCJTB)/Alq 3 /Al and ITO/NPB/BCP/Alq 3 /Alq 3:DCJTB/Alq 3 /Al were studied.NPB was chosen as a hole-transporting/blue-emitting layer.Alq 3 adjacent to BCP acted as a green emitting layer while that adjacent to the Al cathode acte... 相似文献
5.
制备了结构为ITO/BCP或Alq3(x=0,2,6,10,20,40 nm)/C60(50 nm)/Rubrene(50 nm)/MoO3(5nm)/Al(130 nm)的倒置异质结有机太阳能电池,其中BCP或Alq3作电子传输层。实验结果表明:当BCP或Alq3≤6 nm时,器件性能随电子传输层厚度的变化不大;当BCP或Alq3≥10 nm时,随电子传输层厚度的增加,含Alq3器件的性能衰减很快,含BCP器件的性能衰减相对较慢,且其开路电压保持不变。分析表明:当电子传输层较薄时,粗糙的ITO使电子较容易从C60注入到ITO;当电子传输层较厚时,BCP/C60之间的能带弯曲使二者之间几乎不存在势垒,含BCP器件性能较差主要源于BCP较差的电子迁移率,而含Alq3器件性能较差主要源于Alq3/C60之间的势垒。 相似文献
6.
We report spin transport through the silicon in novel magnetic junction with half metallic as free layer and metallic as pinned layer. We used La0.7Sr0.3MnO3 as free layer, FeCo as pinned layer and studied the magnetoresistance through silicon as spacer layer. We fabricated this magnetic tunnel junction using RF/DC sputtering technique over SrTiO3 substrate. Tunneling magnetoresistance (TMR) measurement for this junction at room temperature was found to be 1.1 %. At 2 K, we found a large magnetoresistance of 396 %. TMR found to be increased with decreasing temperature. The results are discussed. 相似文献
7.
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. 相似文献
8.
J. H. Lee In-Woo Chang S. J. Byun T. K. Hong K. Rhie W. Y. Lee Kyung-Ho Shin Chanyong Hwang S. S. Lee B. C. Lee 《Journal of magnetism and magnetic materials》2002,240(1-3):137-139
An unusually large enhancement of TMR at 77 K was observed in double barrier tunnel junctions (DBTJ). This is explained with extended Julliere's model which yields a twice larger TMR value. When the spin coherence length is much smaller at higher temperature, DBTJ is shown to work as a series of two single barrier tunnel junctions. 相似文献
9.
The influence of the finite thickness and structure, amorphous or crystalline, of Fe electrodes on the tunneling magnetoresistance (TMR) ratio is investigated by ab initio calculations in Fe/MgO/Fe tunnel junctions. An amorphous Fe layer in direct contact with the MgO barrier causes a low TMR ratio of only 44%. By inserting crystalline Fe monolayers between the barrier and the amorphous Fe the TMR ratio increases rapidly and reaches the same level as for semi-infinite Fe electrodes. Even one crystalline Fe monolayer is sufficient to achieve a giant TMR ratio exceeding 500%. Omitting the amorphous Fe has nearly no influence on the results if there are more than two monolayers of crystalline Fe next to the barrier. The results demonstrate that the reservoirs can even be nonmagnetic. The TMR emerges from the interplay of symmetry selection in the barrier and spin filtering at the electrode-barrier interface. 相似文献
10.
有机多层量子阱结构的光致发光特性的研究 总被引:2,自引:1,他引:1
采用多源高真空有机分子束沉积系统(OMBDs),将两种有机小分子材料PBD和Alq3以交替生长的方式,制备了不同厚度的PBD/Alq3有机多层量子阱结构(OMQWs), 并利用电化学循环伏安法和光吸收分别测定了PBD和Alq3的最低空分子轨道(LUMO)和最高占据分子轨道(HOMO)。该结构类似于无机半导体中的Ⅰ型量子阱结构,PBD层作为势垒层,Alq3层作为势阱层和发光层,并进行了小角X射线衍射(XRD)的测量。利用荧光光谱研究了OMQWs光致发光(PL)特性,得到随着阱层厚度的降低,光致发光的峰位将蓝移;同时随垒层厚度的减小,PBD的发光峰逐渐消失。利用量子阱结构可以使PBD的能量有效的传递给Alq3,从而增强Alq3的发光。 相似文献
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12.
A. A. Shokri 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(3):475-481
Theoretical studies on spin-dependent transport in magnetic tunnel
heterostructures consisting of two diluted magnetic semiconductors
(DMS) separated by a nonmagnetic semiconductor (NMS) barrier, are
carried in the limit of coherent regime by including the effect of
angular dependence of the magnetizations in DMS. Based on
parabolic valence band effective mass approximation and
spontaneous magnetization of DMS electrodes, we obtain an
analytical expression of angular dependence of transmission for
DMS/NMS/DMS junctions. We also examine the dependence of spin
polarization and tunneling magnetoresistance (TMR) on barrier
thickness, temperature, applied voltage and the relative angle
between the magnetizations of two DMS layers in GaMnAs/GaAs/GaMnAs
heterostructures. We discuss the theoretical interpretation of
this variation. Our results show that TMR of more than 65% are
obtained at zero temperature, when one GaAs monolayer is used as a
tunnel barrier. It is also shown that the TMR decreases rapidly
with increasing barrier width and applied voltage; however at high
voltages and low thicknesses, the TMR first increases and then
decreases. Our calculations explain the main features of the
recent experimental observations and the application of the
predicted results may prove useful in designing nano spin-valve
devices. 相似文献
13.
基于在聚合物中掺杂染料DCJTB的白色有机电致发光器件 总被引:1,自引:0,他引:1
将Alq3和DCJTB作为掺杂物与基质PVK按照不同比例混合共溶,旋涂成膜,制备了PVK∶Alq3∶DCJTB为发光层的结构为ITO/ PVK∶Alq3∶DCJTB/ BCP/Alq3/LiF/Al的器件,其中Alq3和BCP分别用作电子传输层和空穴阻挡层,PVK用作蓝光发光层和空穴传输层。保持PVK和DCJTB的质量比为100∶1不变,改变PVK和 Alq3的质量比,当PVK和Alq3的质量比为20∶1时,得到了效果较好的白光。器件在电压为14 V时,色坐标达到(0.33,0.36),在10~14 V范围内变化甚微。 相似文献
14.
Oppermann R. Sherrington D. Kiselev M. 《The European Physical Journal B - Condensed Matter and Complex Systems》2004,42(2):187-191
The temperature and voltage dependence of spin transport is theoretically investigated in a new type of magnetic tunnel junction, which consists of two ferromagnetic outer electrodes separated by a ferromagnetic barrier and a nonmagnetic (NM) metallic spacer. The effect of spin fluctuation in magnetic barrier, which plays an important role at finite temperature, is included by taking the mean-field approximation. It is found that, the tunnel magnetoresistance (TMR) and the electron-spin polarization depend strongly on the temperature and the applied voltage. The TMR and spin polarization at different temperatures show an oscillatory behavior as a function of the NM spacer thickness. Also, the amplitude of these oscillations is regularly reduced when the temperature increases. The maximum TMR value, varies approximately from 270
in reverse bias (at T = 0 K) to 25
in forward bias (at
).Received: 25 June 2004, Published online: 14 December 2004PACS:
72.25.Hg Electrical injection of spin polarized carriers - 73.23.Ad Ballistic transport - 73.40.Gk Tunneling 相似文献
15.
16.
Herranz G Ranchal R Bibes M Jaffrès H Jacquet E Maurice JL Bouzehouane K Wyczisk F Tafra E Basletic M Hamzic A Colliex C Contour JP Barthélémy A Fert A 《Physical review letters》2006,96(2):027207
We report on tunneling magnetoresistance (TMR) experiments that demonstrate the existence of a significant spin polarization in Co-doped (La, Sr)TiO(3-delta) (Co-LSTO), a ferromagnetic diluted magnetic oxide system (DMOS) with high Curie temperature. These TMR experiments have been performed on magnetic tunnel junctions associating Co-LSTO and Co electrodes. Extensive structural analysis of Co-LSTO combining high-resolution transmission electron microscopy and Auger electron spectroscopy excluded the presence of Co clusters in the Co-LSTO layer and thus, the measured ferromagnetism and high spin polarization are intrinsic properties of this DMOS. Our results argue for the DMOS approach with complex oxide materials in spintronics. 相似文献
17.
主要报道在器件结构为玻璃衬底/Ag(阳极)/NPB(空穴传输层)/Alq3(电子传输及发光层)/Sm(半透明阴极)/Alq3的顶发射有机电致发光器件中,利用氧等离子体对阳极银的表面进行处理来降低阳极和空穴传输层(Ag/NPB)界面处的空穴注入势垒,提高顶发射有机电致发光器件的性能。主要研究了氧等离子体处理时间对阳极银和顶发射有机电致发光器件光电特性的影响。紫外光电子能谱表明,氧等离子体处理能有效降低Ag/NPB界面处的空穴注入势垒。通过优化处理时间获得最佳器件性能,优化后的器件最大效率可达6.14cd/A。 相似文献
18.
The electronic (quantum) transport in a NG/FB/FG tunnel junction (where NG, FB and FG are a normal graphene layer, a ferromagnetic barrier connected to a gate and a ferromagnetic graphene layer, respectively) is investigated. The motions of the electrons in the graphene layers are taken to be governed by the Dirac Equation. Parallel (P) and antiparallel alignment (AP) of the magnetizations in the barrier and in the ferromagnetic graphene are considered. Our work focuses on the oscillation of the electrical conductance (Gq), of the spin conductance (Gs) and of the tunneling magneto resistance (TMR) of this magnetic tunnel junction. We find that, the quantum modulation due to the effect of the exchange field in FB will be seen in the plots the conductance and of the TMR as functions of the thickness of ferromagnetic barrier (L). The period of two multiplied sinusoidal terms of the modulation are seen to be controlled by varying the gate potential and the exchange field of the FB layer. The phenomenon, a quantum beating, is built up with two oscillating spin conductance components which have different periods of oscillation related to the splitting of Dirac's energies in the FB region. The amplitudes of oscillations of Gq, Gs and TMR are not seen to decrease as the thickness increases. The decaying behaviors seen in the conventional transport through an insulator do not appear. 相似文献
19.
新型稀土铕配合物Eu(o-BBA)3(phen)电致发光研究 总被引:1,自引:1,他引:0
研究了一种新的稀土配合物邻苯甲酰苯甲酸-1,10-菲咯啉-铕(Eu(o-BBA)3(phen))的电致发光特性.采用不同的电子传输层材料,制备了多种结构的有机电致发光器件及有机无机复合器件.比较了单层电致发光器件A:ITO/PVK:Eu/Al与有机无机复合器件B:ITO/PVK:Eu/ZnS/Al发光性能的不同.分析了采用无机半导体材料ZnS作为电子传输层的优点.研究结果表明采用无机的电子传输层,能有效地避免激基复合物的形成,提高器件的亮度同时保持稀土离子发光的色纯性. 相似文献
20.
S. Takahashi T. Yamashita H. Imamura S. Maekawa 《Journal of magnetism and magnetic materials》2002,240(1-3):100-102
The effect of spin relaxation on tunnel magnetoresistance (TMR) in a ferromagnet/superconductor/ferromagnet (FM/SC/FM) double tunnel junction is theoretically studied. The spin accumulation in SC is determined by balancing of the spin-injection rate and the spin-relaxation rate. In the superconducting state, the spin-relaxation time τs becomes longer with decreasing temperature, resulting in a rapid increase of TMR. The TMR of FM/SC/FM junctions provides a useful probe to extract information about spin-relaxation in superconductors. 相似文献