Plastic Multilayered Molecular Organic Light Emitting Diodes

1997 ◽  
Vol 488 ◽  
Author(s):  
George M. Daly ◽  
Hideyuki Murata ◽  
Charles D. Merritt ◽  
Zakya H. Kafafi ◽  
Hiroshi Inada ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Power Efficiency ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Electron Transport Layer ◽  
Light Emitting ◽  
Organic Light ◽  
Device Structures ◽  
External Quantum Yield

AbstractEnhanced performance has been observed for plastic molecular organic light emitting diodes (MOLEDs) consisting of two to four organic layers sequentially vacuum vapor deposited onto patterned indium-tin oxide (ITO) on polyester films. For all device structures studied, the performance of plastic diodes is comparable to or better than their analogs on glass substrates. At 100 A/m2, a luminous power efficiency of 4.4 lm/W and external quantum yield of 2.7% are measured for a device structure consisting of two hole transport layers, a doped emitting layer and an electron transport layer on a polyester substrate. The same device made on a silica substrate has a luminous power efficiency of 3.5 lm/W and external quantum yield of 2.3%. Electrical and optical performance for comparable device structures has been characterized by current-voltage-luminance measurements and electroluminescence spectra collected normal to the emitting surface. In addition, an integrating sphere was used to collect the total light emitted and to determine the optical output coupling on glass versus plastic substrates.

Improve the Charge Balance of White Phosphorescent Organic Light Emitting Diodes Using Co-Doped Electron Transport Layer in Emitting Layer

2011 ◽  
Vol 287-290 ◽  
pp. 3051-3055
Author(s):  
Yu Sheng Tsai ◽  
Lin Ann Hong ◽  
Fuh Shyang Juang ◽  
Kuang Chih Lai ◽  
Chang Jun Lai ◽  
...  
Keyword(s):  
Electron Transport ◽  
Power Efficiency ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Electron Transport Layer ◽  
Driving Voltage ◽  
Light Emitting ◽  
Organic Light ◽  
Luminance Efficiency

White phosphorescent organic light-emitting diodes (WPHOLED) with high efficiency and low driving voltage were achieved by incorporating an electron transport material (3TPYMB) into a hole transport-type host (TCTA) as a mixed-host structure. For electrons, the emitting layer is nearly barrier-free until they reach the region of exciton formation, which keeps the driving voltage low. Therefore, improved the charge carrier balance within the emitting layer and enhanced the power efficiency of device. White PHOLED at a luminance of 1000 cd/m2 shown a driving voltage of 4.38 V, luminance efficiency of 36.1 cd/A, and power efficiency of 26.4 lm/W was observed. Furthermore, the power efficiency can be improved to 34.27 lm/W, and luminance efficiency to 46.7 cd/A by attaching a brightness enhancement film (BEF).

Numerical Simulation on the Electronic Properties in Multilayer Organic Light Emitting Diodes

2012 ◽  
Vol 629 ◽  
pp. 224-228 ◽  
Author(s):  
Kwang Sik Kim ◽  
Young Wook Hwang ◽  
Tae Young Won
Keyword(s):  
Numerical Simulation ◽  
Charge Transport ◽  
Electronic Properties ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Light Emitting ◽  
Organic Light

We report our finite element method (FEM) simulation study on the characteristic of the charge transport layer of the multi-layer structure for organic light emitting diodes (OLEDs). The physical model cover all the key physical processes in OLEDs, namely charge injection, transport and recombination, exciton diffusion, transfer and decay for electronic properties. We performed a numerical simulation on a multilayer structure comprising a hole transport layer (HTL), an emission layer (EML), and an electron transport layer (ETL) between both electrodes; anode and cathode. The materials of the HTL is TPD (N, N'-Bis (3- methylphenyl) - N, N'- bis (phenyl) benzidine), and the ETL includes Alq3 (Tris (8- hyroxyquinolinato) aluminium). Here, we investigated the parameters such as recombination rates which influence the efficiency of the charge transport between layers in bilayer OLEDs. We also analyzed a transient response during the turn on period and the carrier transport in accordance with the variation of the injection barrier and applied voltage. In addition, this paper revealed that the effect of the insertion of the EML in bilayer structure.

Degradation of Bilayer Organic Light-Emitting Diodes Studied by Impedance Spectroscopy

2016 ◽  
Vol 16 (4) ◽  
pp. 3368-3372 ◽  
Author(s):  
Shuri Sato ◽  
Masashi Takata ◽  
Makoto Takada ◽  
Hiroyoshi Naito
Keyword(s):  
Impedance Spectroscopy ◽  
Light Emitting Diodes ◽  
Device Simulation ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Organic Light

The degradation of bilayer organic light-emitting diodes (OLEDs) with a device structure of N, N′-di(1-naphthyl)-N, N′-diphenylbenzidine (α-NPD) (hole transport layer) and tris-(8-hydroxyquinolate)aluminum (Alq3) (emissive layer and electron transport layer) has been studied by impedance spectroscopy and device simulation. Two modulus peaks are found in the modulus spectra of the OLEDs below the electroluminescence threshold. After aging of the OLEDs, the intensity of electroluminescence is degraded and the modulus peak due to the Alq3 layer is shifted to lower frequency, indicating that the resistance of the Alq3 layer is increased. Device simulation reveals that the increase in the resistance of the Alq3 layer is due to the decrease in the electron mobility in the Alq3 layer.

scholarly journals The application of a non-doped composite hole transport layer of [MoO3/CBP]n with multi-periodic structure for high power efficiency organic light-emitting diodes

RSC Advances ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 4957-4962 ◽  
Author(s):  
Zhixiang Gao ◽  
Zilong Feng ◽  
Weihua Chen ◽  
Wenshan Qu ◽  
Wei Ao ◽  
...  
Keyword(s):  
Periodic Structure ◽  
Power Efficiency ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Organic Light ◽  
High Power Efficiency

A non-doped multi-periodic structure of composite hole transport layer of [MoO3/CBP]n was applied to organic light-emitting diodes.

scholarly journals Efficient green electroluminescence based on an iridium(iii) complex with different device structures

RSC Advances ◽  
2017 ◽  
Vol 7 (5) ◽  
pp. 2615-2620 ◽  
Author(s):  
Yi-Ming Jing ◽  
You-Xuan Zheng ◽  
Jing-Lin Zuo
Keyword(s):  
Current Efficiency ◽  
Power Efficiency ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Iridium Complex ◽  
Device Structure ◽  
Light Emitting ◽  
Organic Light ◽  
Device Structures ◽  
Maximum Current

Organic light-emitting diodes based on an iridium complex using different device structure show high performances with a maximum current efficiency of 86.5 cd A−1and a maximum power efficiency of 52.2 lm W−1, respectively.

scholarly journals Solution-Processed Efficient Blue Phosphorescent Organic Light-Emitting Diodes (PHOLEDs) Enabled by Hole-Transport Material Incorporated Single Emission Layer

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 554
Author(s):  
Taeshik Earmme
Keyword(s):  
Light Emitting Diodes ◽  
Blue Emission ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Emission Layer ◽  
Solution Processed ◽  
Light Emitting ◽  
Organic Light ◽  
Single Emission ◽  
Blue Phosphorescent

Solution-processed blue phosphorescent organic light-emitting diodes (PHOLEDs) based on a single emission layer with small-molecule hole-transport materials (HTMs) are demonstrated. Various HTMs have been readily incorporated by solution-processing to enhance hole-transport properties of the polymer-based emission layer. Poly(N-vinylcarbazole) (PVK)-based blue emission layer with iridium(III) bis(4,6-(di-fluorophenyl)pyridinato-N,C2′)picolinate (FIrpic) triplet emitter blended with solution-processed 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) gave luminous efficiency of 21.1 cd/A at a brightness of 6220 cd/m2 with an external quantum efficiency (EQE) of 10.6%. Blue PHOLEDs with solution-incorporated HTMs turned out to be 50% more efficient compared to the reference device without HTMs. The high hole mobility, high triplet energy of HTM, and favorable energy transfer between HTM blended PVK host and FIrpic blue dopant were found to be important factors for achieving high device performance. The results are instructive to design and/or select proper hole-transport materials in solution-processed single emission layer.

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