Light-Emitting and Hole-Transporting Polymers for LEDs

1997 ◽  
Vol 488 ◽  
Author(s):  
Toshihiro Ohnishi ◽  
Shuji Doi ◽  
Masato Ueda ◽  
Fumi Yamaguchi ◽  
Takanobu Noguchi
Keyword(s):  
High Efficiency ◽  
Hole Mobility ◽  
Hole Injection ◽  
Side Chain ◽  
High Luminance ◽  
Strong Fluorescence ◽  
Light Emitting ◽  
Hole Transporting ◽  
Hole Transporting Material ◽  
Injection Barrier

AbstractVarious copolymers of arylene vinylenes, having strong fluorescence, showed predominantly the emission in the multi-layer device using an electron-transporting material(ETM) such as tris(8-quinolinolato)aluminum(Alq3). The emission from Alq3 was suppressed due to the high hole-injection barrier from the copolymers to ETM in spite of low or no barriers of electron injection from ETM to the copolymers. We have successfully prepared highly hole-transporting polysilane having a triphenylamine group as a side chain(TPA-PS). The hole mobility as high as 10 cm3cm2/Vs is attributable to the intermolecular hopping process facilitated by the interaction between the polysilane backbone and the triphenylamine group. The polysilane is effectively used as a hole transporting material. The bilayer LED device consisting of TPA-PS and Akb3 showed high luminance (2000cd/m2) and high efficiency (4cd/A).

P-94: Improvement in Hole Injection into Quantum-dot Light-emitting Layer Using Organic Hole-transporting Material/Molybdenum Oxide Composite

2016 ◽  
Vol 47 (1) ◽  
pp. 1476-1479 ◽  
Author(s):  
Tomoya Hirose ◽  
Takao Hamada ◽  
Toshiaki Tsunoi ◽  
Eriko Aoyama ◽  
Ayumi Ishigaki ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Molybdenum Oxide ◽  
Hole Injection ◽  
Light Emitting ◽  
Oxide Composite ◽  
Hole Transporting ◽  
Hole Transporting Material

Inkjet printing high luminance phosphorescent OLED based on m-MTDATA:TPBi host

2019 ◽  
Vol 33 (12) ◽  
pp. 1950149 ◽  
Author(s):  
Xing Xing ◽  
Tong Lin ◽  
Yong-Xu Hu ◽  
Yu-Ling Sun ◽  
Wan-Ying Mu ◽  
...  
Keyword(s):  
Charge Transfer ◽  
High Performance ◽  
High Luminance ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Single Host ◽  
Hole Transporting ◽  
Phosphorescent Material ◽  
Hole Transporting Material ◽  
Balance Charge

In organic light-emitting devices (OLEDs), the high performance of devices depends on balanced charge transfer in emitting layer (EML). However, the balance charge transfer is hard to achieve in the single host material-based EML. In this work, a high luminance co-host based OLEDs is printed. In detail, green phosphorescent material tris[2-(p-tolyl)pyridine]iridium(III) [Formula: see text] is used as dopant, and a hole-transporting material [Formula: see text]-tris[3-methy-lphenyl(phenyl)amino]-triphenylamine (m-MTDATA) blended with an electron-transporting material 1,3,5-tris(phenyl-2-benzimidazolyl)-benzene (TPBi) as co-host. As a result, the optimized printing co-host OLEDs with 10 wt.% [Formula: see text] shows a maximum luminance of [Formula: see text], which is much higher than the CDBP counterpart.

Controlled Injection of Holes into ALQ3 Based Oleds by Means of An Oxidized Transport Layer

2001 ◽  
Vol 708 ◽  
Author(s):  
Mathew K. Mathai ◽  
Keith A. Higginson ◽  
Bing R. Hsieh ◽  
Fotios Papadimitrakopoulos
Keyword(s):  
Indium Tin Oxide ◽  
Oxidative Degradation ◽  
Transport Layer ◽  
Hole Injection ◽  
Carrier Injection ◽  
Salt Loading ◽  
Light Emitting ◽  
Hole Transporting ◽  
Intrinsic Degradation ◽  
Variable Conductivity

ABSTRACTIn this paper we report a method for tuning the extent of hole injection into the active light emitting tris- (8-hydroxyquinoline) aluminum (Alq3) layer in organic light emitting diodes (OLEDs). This is made possible by modifying the indium tin oxide (ITO) anode with an oxidized transport layer (OTL) comprising a hole transporting polycarbonate of N,N'-bis(3-hydroxymethyl)-N,N'-bis(phenyl) benzidine and diethylene glycol (PC-TPB-DEG) doped with varying concentrations of antimonium hexafluoride salt of N,N,N',N'-tetra-p-tolyl-4,4'-biphenyldiamine (TMTPD+ SbF6-). The conductivity of the OTL can be changed over three orders of magnitude depending on salt loading. The analysis of hole and electron current variations in these devices indicates that optimizing the conductivity of the OTL enables the modulation of hole injection into the Alq3 layer. The bipolar charge transport properties for OLEDs in which the interfacial carrier injection barriers have been minimized, are governed by the conductivities of the respective layers and in this case it is shown that the variable conductivity of the OTL does allow for better control of the same. Accordingly, varying the concentration of holes in the device indicates that beyond an optimum concentration of holes, further hole injection results in the formation of light quenching cationic species and the initiation of oxidative degradation processes in the Alq3 layer, thus accelerating the intrinsic degradation of these devices. The variable conductivity of the OTL can hence be used to minimize the occurrence of these processes.

scholarly journals High efficiency blue organic light-emitting diodes with below-bandgap electroluminescence

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Maria Vasilopoulou ◽  
Abd. Rashid bin Mohd Yusoff ◽  
Matyas Daboczi ◽  
Julio Conforto ◽  
Anderson Emanuel Ximim Gavim ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
High Mobility ◽  
Organic Light Emitting Diodes ◽  
Triplet Energy ◽  
Material Interface ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Hole Transporting

AbstractBlue organic light-emitting diodes require high triplet interlayer materials, which induce large energetic barriers at the interfaces resulting in high device voltages and reduced efficiencies. Here, we alleviate this issue by designing a low triplet energy hole transporting interlayer with high mobility, combined with an interface exciplex that confines excitons at the emissive layer/electron transporting material interface. As a result, blue thermally activated delay fluorescent organic light-emitting diodes with a below-bandgap turn-on voltage of 2.5 V and an external quantum efficiency (EQE) of 41.2% were successfully fabricated. These devices also showed suppressed efficiency roll-off maintaining an EQE of 34.8% at 1000 cd m−2. Our approach paves the way for further progress through exploring alternative device engineering approaches instead of only focusing on the demanding synthesis of organic compounds with complex structures.

Influence of hole transporting material on device performance in organic light-emitting diode

2000 ◽  
Vol 363 (1-2) ◽  
pp. 290-293 ◽  
Author(s):  
Shizuo Tokito ◽  
Koji Noda ◽  
Kou Shimada ◽  
Shin-ichiro Inoue ◽  
Makoto Kimura ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Device Performance ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light ◽  
Hole Transporting ◽  
Hole Transporting Material

A High Tg Carbazole-Based Hole-Transporting Material for Organic Light-Emitting Devices

2005 ◽  
Vol 17 (5) ◽  
pp. 1208-1212 ◽  
Author(s):  
Jiuyan Li ◽  
Di Liu ◽  
Yanqing Li ◽  
Chun-Sing Lee ◽  
Hoi-Lun Kwong ◽  
...  
Keyword(s):  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light ◽  
Hole Transporting ◽  
Organic Light Emitting Devices ◽  
Hole Transporting Material

scholarly journals Use of Hybrid PEDOT:PSS/Metal Sulfide Quantum Dots for a Hole Injection Layer in Highly Efficient Green Phosphorescent Organic Light-Emitting Diodes

2021 ◽  
Vol 9 ◽  
Author(s):  
Wenqing Zhu ◽  
Kuangyu Ding ◽  
Chen Yi ◽  
Ruilin Chen ◽  
Bin Wei ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Efficiency ◽  
Light Emitting Diode ◽  
Metal Sulfide ◽  
Molybdenum Sulfide ◽  
Hole Injection ◽  
Light Emitting ◽  
Hole Injection Layer ◽  
Highly Efficient ◽  
Organic Light

In this study, we have synthesized the molybdenum sulfide quantum dots (MoS2 QDs) and zinc sulfide quantum dots (ZnS QDs) and demonstrated a highly efficient green phosphorescent organic light-emitting diode (OLED) with hybrid poly (3,4-ethylenedioxythiophene)/poly (styrenesulfonate) (PEDOT:PSS)/QDs hole injection layer (HIL). The electroluminescent properties of PEDOT:PSS and hybrid HIL based devices were explored. An optimized OLED based on the PEDOT:PSS/MoS2 QDs HIL exhibited maximum current efficiency (CE) of 72.7 cd A−1, which shows a 28.2% enhancement as compared to counterpart with single PEDOT:PSS HIL. The higher device performance of OLED with hybrid HIL can be attributed to the enhanced hole injection capacity and balanced charge carrier transportation in the OLED devices. The above analysis illustrates an alternative way to fabricate the high efficiency OLEDs with sulfide quantum dots as a HIL.

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