共查询到20条相似文献,搜索用时 31 毫秒
1.
S. Y. Yang X. L. Zhang Z. D. Lou Y. B. Hou 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(2):151-154
Electroluminescence (EL) of bilayer organic light-emitting diodes based on N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine
(TPD) and 2-(4'-biphenyl)-5-(4”-tert-butylphenyl)-1,3,4-oxadiazole (PBD) were reported. The EL spectra of bilayer device ITO/TPD/PBD/Al consist of monomolecular
emission from TPD, exciplex emission and charge carriers cross recombination at the TPD/PBD interface. By varying the thickness
of each organic layer while keeping the thickness of the whole device constant, three kinds of bilayer devices were fabricated
and their EL and photoluminescence spectra were compared with each other, and our experimental data show that charge tunneling
and cross recombination coexist at the TPD/PBD interface, and these two processes compete with each other under high electric
fields. 相似文献
2.
Tuning of the emission color of organic electroluminescent devices by exciplex formation at the organic solid interface 总被引:1,自引:0,他引:1
′ ,4′′-tris(3-methylphenylphenylamino)triphenylamine, 1,3,5-tris[(4-diphenylaminophenyl)phenylamino]benzene, N, N′-bis(3-methylphenyl)-N, N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine, and 4,4′,4′′-tri(N-carbazolyl)triphenylamine, emitted bright light resulting from the exciplex formed at the solid interface between TPOB
and the hole-transporting material. The exciplex formation was evidenced by the measurements of the photoluminescence spectra
and lifetimes of the mixture of an equimolar amount of TPOB and each of the hole-transporting materials. Tuning of the emission
color from greenish blue to orange was attained by varying the ionization potential of the hole-transporting material for
the fixed electron-transporting material of TPOB.
Received: 27 July 1998/Accepted: 28 July 1998 相似文献
3.
混合发光层有机电致发光器件中的多重成分发射 总被引:3,自引:3,他引:0
以等摩尔空穴传输材料TPD和电子传输材料PBD组成结构为ITO/TPD/TPD∶PBD/PBD/Al的混合物发光层有机电致发光(EL)器件,观察到了相对于组成材料的荧光光谱红移的宽发射带。通过比较EL光谱,光致发光光谱及EL光谱分解,表明电致发光中同时包含单体发射、激基复合物和电荷对复合物的发射。激基复合物为TPD的激发态TPD*与PBD的基态相互作用形成TPD*PBD类型的复合物,电荷对复合物是带电荷的空穴传输分子(D+)的空穴和电子传输分子(A-)的电子交叉复合而形成的(D+-A-)*复合物。各激发态在电场作用下呈现不同的形成机理和复合过程,并且单体发射和激发态复合物的比例随电场而变化,导致发射光谱随电场增强而蓝移。该器件的最高亮度和最大外部量子效率分别为240 cd·(cm2)-1和0.49%。有机固态界面激基复合物或电荷对复合物的发射常出现宽的红移发射带,是调节发光颜色的有效手段。 相似文献
4.
Jung Kyu Kim Dong-Hyun Lee Dong Hwan Wang Sung M. Cho Jun Young Lee Jong Hyeok Park 《Journal of luminescence》2012,132(3):870-874
This study investigates enhanced electrophosphorescence and its mechanism in poly(N-vinyl carbazole) (PVK): N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1-biphenyl]-4,4′-diamine (TPD)/2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD): fac-tris(2-phenylpyridine)iridium [Ir(ppy)3] concentration graded bilayer electroluminescence devices. The two layers are partially intermixed at the bilayer interface because the upper layer (composed of Ir(ppy)3 and PBD) was spun cast from a solvent that slightly swells the bottom layer (composed of PVK and TPD). Moreover, PBD in the upper layer can act as an efficient electron transport layer as well as a hole blocking layer, resulting in greatly enhanced electron–hole recombination. An indium tin oxide (ITO)/3,4-polyethylenedioxythiophene–polystyrenesulfonate (PEDOT)/[PVK:TPD/Ir(ppy)3:PBD] bilayer/LiF/Al device showed dramatically decreased turn-on and driving voltages, enhanced luminescence efficiency, and narrower emission spectra compared to those of conventional ITO/PEDOT:PSS/[PVK:TPD:Ir(ppy)3:PBD] blend/LiF/Al devices. 相似文献
5.
Organic light-emitting diodes (OLEDs) based on the blend of two blue luminescent materials N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-diphenyl-4,4′-diamine (NPB) and 2-(4-biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD) were fabricated. The electroluminescence (EL) spectra of this device showed a new emission that is different from their intrinsic exciton emission. Compared with the photoluminescence (PL) spectra of single layer NPB and PBD, respectively, there was an apparent red shift in that of their blend. Thus the exciplex formation in the blend can be concluded due to the similar emission in both PL and EL spectra. The exciplex formation process and the effect of applied voltage were analyzed by Gaussian fitting. 相似文献
6.
Yu Duan Feng He Ping Chen Yi Zhao Shiyong Liu Yuguang Ma 《Optical and Quantum Electronics》2008,40(1):57-63
We demonstrate a promising single layer white light-emitting device using a dimeric trimeric phenylenvinylene derivative as
emitting layer. The broad electroluminescence emission band is composed of blue component from singlet excited state of individual
2, 5, 2′, 5′-tetra (p-trifluoromethylstyryl)-biphenyl molecule and long-wavelength electromer emission in electroluminescence. Therefore, white-light
emission can also be obtained with a typical three-layer structure of ITO/NPB (50 nm)/TFM-TSB (50 nm)/Alq3 (30 nm)/LiF/Al device. The maximum brightness of this device is 809 cd/m2 at 217 mA/cm2 and 13 V, and the maximum luminous efficiency is 1.49 cd/A at 11 mA/cm2 and 8 V.
相似文献
7.
8.
Bo Jiao Zhaoxin Wu Xingwei Yan Xun Hou 《Applied Physics A: Materials Science & Processing》2010,98(1):239-243
We investigated the influence of the thickness of hole-transport layer, N,N′-biphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine (NPB), on the performance of the typical bi-layer organic light-emitting diodes
(OLEDs). It was found that both the current efficiency and the power efficiency of bi-layer OLEDs were improved when the thickness
of the hole-transport layer varied from 30 to 120 nm. By investigating the hole-injection efficiency of ITO/NPB contact with
various thicknesses of NPB film, we found that the hole-injection efficiency was reduced with the thickness of NPB layer increasing
from 60 to 180 nm, which improved the injected carriers balance in devices and increased the efficiency of the bi-layer OLEDs. 相似文献
9.
We demonstrate molecular organic white light-emitting devices (LEDs), using vacuum-deposited thin films of N,N-diphenyl-N,N-bis(1-naphthyl)-(1,1-biphenyl)-4,4-diamine (NPB) as the hole-transporting layer, 1,6-bis(2-hydroxyphenyl)pyridine boron complex ((dppy)BF) as the emitting layer, tris-(8-hydroxyquinoline)aluminum (Alq) doped with 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) as the red-emitting layer. The white light comes from three components: exciplex emission at the interface between NPB and (dppy)BF, which covers the wide range from 500 to 700 nm, blue emission from bulk NPB and (dppy)BF and red emission from DCJTB. The chromaticity of the devices can be tuned by varying the thickness of (dppy)BF and doped Alq layers. The Commission Internationale De L'Eclairage (CIE) coordinates of emitted light vary from (0.31, 0.335) to (0.32, 0.345) when forward voltages change from 10 to 20 V, which are just adjacent to the white-light equi-energy point (0.33, 0.33). The brightness and luminous efficiency are 150 cd/m2 and 0.3l m/W at 12 V, respectively. 相似文献
10.
De-Wei Zhao Fu-Jun Zhang Su-Ling Zhao Guang-Cai Yuan Hong-Hua Xu 《Applied Surface Science》2007,253(8):4025-4028
Organic light-emitting diode (OLED) based on two kinds of blue emission materials N,N′-bis(1-naphthyl)-N,N′-diphenyl-l,l′-diphenyl-4,4′-diamine (NPB) and 2-(4-biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD) was fabricated. There is only one emission peak in photoluminescence (PL) spectrum which originates from NPB exciton emission. And the electroluminescence (EL) emission peaks have an apparent red-shift with the increase of driving voltage. The red-shift emission from exciplex emission could be ruled out. Thus, by the method of Gaussian fitting it should be ascribed to the overlap of exciton emission and electroplex emission which occurs at the interface between NPB and PBD. The formation of the electroplex emission under high electric field is analyzed. 相似文献
11.
为研究激基复合物器件激子复合区域的变化,在TPD/BPhen界面可形成激基复合物发光的基础上,以Ir(pq)2(acac)为探测层,制备器件ITO/Mo O_3(2.5 nm)/TPD((40-x)nm)/Ir(pq)2(acac)(0.5 nm)/TPD(x,x=0,3,6,10 nm)/BPhen(40 nm)/Cs2CO_3/Al,其中靠近BPhen的TPD称之为间隔层。电致发光光谱表明,该组器件的激子复合区域主要位于Ir(pq)2(acac)薄层和TPD/BPhen界面,分别发射595 nm和478 nm的光。随着TPD间隔层厚度的增加和电压的升高,发光区域向激基复合物区域(TPD/BPhen界面)移动,即更多的电子和空穴在TPD/BPhen界面形成激基复合物发光,Ir(pq)2(acac)发光减弱。当间隔层厚度由0 nm增至10nm时,6 V电压下的Ir(pq)2(acac)和激基复合物发光强度的比值由44降至1.5。对于间隔层厚度为6 nm的器件,Ir(pq)2(acac)和激基复合物发光强度的比值由6 V时的2.8降至10 V时的1.0。由此可见,激基复合物给体作间隔层能有效调节激子复合区域。 相似文献
12.
This study examined the electrical and optical properties of red OLEDs (organic light-emitting diodes) with a four-layer structure,
ITO/amorphous fluoropolymer (AF)/N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1-biphenyl-4,4′-diamine (TPD)/R-H:R-D/lithium fluoride (LiF)/Al, containing a hole injection material,
AF (amorphous fluoropolymer) and an electron injection layer material, LiF. Compared to the basic structure (two-layer structure),
the brightness and luminous efficiency of the four-layer structure, ITO/TPD/R-H:R-D/Al, increased approximately 100 times
(30,000 lm/m2) and 150 times (51 lm/W), respectively, with an applied voltage. The excellent efficiency of the external proton was also
increased 150 times (0.51%). That is, the hole and electron injection layers improved the surface roughness of ITO and Al,
and the interfacial physical properties. In addition, these layers allowed the smooth injection of holes and electrons. The
luminance, luminous efficiency and external quantum efficiency were attributed to an increase in the recombination rates. 相似文献
13.
A blue shifted photoluminescent emission in bis(2-(2′-hydroxyl phenyl)benzthiazolate)zinc (II) complex, ZBZT, arises out of the dimeric structure, typical of the localized electron density around the non-bridged ligand in the excited state of the complex. An average decay lifetime of 4.8 and 3.0 ns for the ligand and the complex, respectively indicates an energy transfer from the ligand to the metal. A PL quantum efficiency of about ?ZBZT=0.45 in DMF solution is observed, in comparison to the Alq3, complex, ?Alq3=0.116. Semi empirical ZINDO/S-SCF-CI calculations support the dominance of non-bridged ligand moiety in controlling the photoluminescent properties. An unusually broad white light (FWHM ∼220 nm) electroluminescent emission in the two layer device structure brings out the features of an exciplex formation between the active layer ZBZT/TPD interface, which is studied at different current densities. Such a broadened emission is verified for different thicknesses of the active layer substantiating the role of exciplex formation. 相似文献
14.
15.
Ching-Liang Wei Ying-Chung Chen Chien-Chuan Cheng Kuo-Sheng Kao 《Applied Physics A: Materials Science & Processing》2008,91(3):501-506
Bright and efficient stacked color-tunable organic light emitting devices (OLEDs) using an intermediate Al/Au electrode have
been reported. The effects of the thicknesses of Al and Au layers on the luminance characteristics have been comprehensively
studied. After optimization, the bottom-emission single-unit OLED of 4,4′,4′′-Tris(N-3-methylphenyl-N-phenyl-amino) triphenylamine/N,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine/tris(8-hydroxyquinoline) aluminum has a maximum luminance efficiency (ηL) of 3.37 cd/A by using Al/Au as the cathode and 2.92 cd/A by using Al/Au as the anode. Meanwhile, by introducing the optimized
intermediate Al/Au electrode into the stacked color-tunable (red to blue) OLEDs, a red unit with maximum ηL of 4.73 cd/A and a blue unit with maximum ηL of 3.96 cd/A have been obtained. The color can be tuned efficiently along a linear route from pure red with the Commission
Internationale de l’Eclairage (CIE) coordinates of (0.662, 0.330) to sky blue with the CIE coordinates of (0.155, 0.340).
This scheme can be a potential candidate for achieving high-brightness and efficient stacked color-tunable OLEDs.
PACS 78.60.Fi; 78.66.Qn; 81.05.Lg; 85.30.De 相似文献
16.
Both phosphorescent materials and devices, which emit red and green light, already have great performance and breakthrough.
The biggest challenge and bottleneck is the blue phosphorescent device, if we want to popularize phosphorescent organic light-emitting
device (OLED) in the full-color panel. This paper brings a new quantum-well structure in light-emitting layer. We select the
commonly used phosphor materials, N,N′-dicarbazoly-2,5-benzene (mCP) and bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III) (FIrpic). The structure
of the device is indium-tin oxide (ITO)/N,N′-bis(naphthalene-1-y1)-N,N′-bis(phenyl)-benzidine (NPB)/di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane (TAPC)/mCP/FIrpic/mCP/4,7-dipheny1-1,10-phenanthroline (Bphen)/Mg:Ag. The blue OLED of
good performance is achieved by adjusting the thickness of FIrpic. When the thickness of FIrpic is 0.2 nm and the Current
density is 34.86 mA/cm2, the results show that the luminance of the device is 1000 cd/m2, then the luminous power efficiency of the device is 6.01 lm/W. Meanwhile, the light emitting mechanism of ultrathin quantum-well
structure is well studied, the quantum confinement effect and the role of quantum well structure as the light-emitting layer
in the blue phosphorescent devices are mainly analyzed. 相似文献
17.
Zhang Ye Hao Yuying Meng Weixin Xu Huixia Wang Hua Xu Bingshe 《Applied Physics A: Materials Science & Processing》2012,106(3):709-715
The electroplex between (2-(4-trifluoromethyl-2-hydroxyphenyl)benzothiazole) zinc [Zn(4-TfmBTZ)2] as an electron-acceptor and N,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine (NPB) as an electron-donor was
characterized by bilayer, blend, and multilayer quantum-well (MQW) device, respectively. The blend composition and quantum-well
number are effective parameters for tuning electroluminescence color. White light with high color purity and color rendering
index (CRI) was observed from these devices based on Zn(4-TfmBTZ)2/NPB. Moreover, the blend and MQW devices all exhibit high operation stability, hence excellent color stability. For the device
with 5 mol% NPB in blend layer, its Commission International Del’Eclairage (CIE) coordinate region is x=0.28–0.31, y=0.33–0.35 and CRI is 83.3–91.2 at 5–9 V. For MQW structure device with NPB of 60 nm thickness, its CIE coordinate region
is x=0.29–0.32, y=0.31–0.34 and CRI=87.9–92.5 at 10–15 V. Such high color stability and purity and CRI, being close to ideal white light, are
of current important for white OLED. 相似文献
18.
Zhaokui Wang Shigeki Naka Hiroyuki Okada 《Applied Physics A: Materials Science & Processing》2011,102(3):681-687
Injection properties of electrons and holes in a mixed single layer organic light emitting device with mixed small molecules
tris-(8-hydroxy-quinoline) aluminum (Alq3), 2,5-bis(6′-(2′,2″-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), 4′-bis[N-(1-napthyl)-N-phenyl-amino]biphenyl
(α-NPD), and 5,6,11,12-tetraphenylnaphthacene (rubrene) were investigated using Au/MoO3 as hole and Al alloy as electron injection electrodes. On the basis of measuring the temperature dependence of currents through
the interface between the electrodes and the mixed single organic layer, the carrier injection mechanism was primarily ascribed
to the Schottky thermionic emission with the barrier height of 0.25 eV for holes and 0.67 eV for electrons. By adding the
dopant material rubrene and the electron transport material PyPySPyPy into the mixed single layer, the barrier height of electrons
could be reduced. The interfacial state analysis demonstrated that the electron barrier height was also dependent on the interfacial
conditions of the device. 相似文献
19.
Two novel and neutral benzimidazole derivatives-based anion receptors bearing a 1,10-phenanthroline fluorophore, N,N′-di-(2′-benzimidazolyl-methylene)-1, 10-phenanthroline-2,9-diamide (1) and N,N′-di-[2′-(benzimidazolyl-2′-) ethyl-]-1,10-phenanthroline-2,9-diamide (2), which exhibited turn-on and turn-off fluorescence
responses to various anions, were rationally designed and synthesized and their fluorescent response toward anions was investigated
in DMSO solution. In the process of anions binding, there were two different fluorescent responses in presence of anions:
a quenching of the fluorescence emission for F- and AcO- and an enhancement of the fluorescence emission for Cl−, Br− and I−. Two different luminescent mechanisms of the receptors 1 and 2 resulting from various anions were exploited to rationalize
quenching and enhancement of the fluorescence emission: a photo-induced electronic transfer mechanism (PET) and the increase
of the rigidity of the host molecules, respectively. In particular, chloride could be recognized selectively from the anions
tested according to changes of fluorescence spectrum.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献