Fabrication of Micro-OLEDs by Room-temperature Curing Nanocontact-print Lithography Using DLC Molds

2012 ◽  
Vol 1511 ◽  
Author(s):  
Ippei Ishikawa ◽  
Keisuke Sakurai ◽  
Shuji Kiyohara ◽  
Taisuke Okuno ◽  
Hideto Tanoue ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Nanoimprint Lithography ◽  
Room Temperature ◽  
Hole Transport ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Insulating Layer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Ito Glass

ABSTRACTThe microfabrication technologiesfor organic light-emitting devices (OLEDs) are essential to the fabrication of the next generation of light-emitting devices. The micro-OLEDs fabricated by room-temperature curing nanoimprint lithography (RTC-NIL) using diamond molds have been investigated. However, light emissions from 10 μm-square-dot OLEDs fabricated by the RTC-NIL method have not been uniform. Therefore, we proposed the fabrication of micro-OLEDs by room-temperature curing nanocontact-print lithography (RTC-NCL) using the diamond-like carbon (DLC) mold. The DLC molds used in RTC-NCL were fabricated by an electron cyclotron resonance (ECR) oxygen ion shower with polysiloxane oxide mask in electron beam (EB) lithography technology. The mold patterns are square and rectangle dots which has 10 µm-width, 10 µm-width and50 µm-length, respectively. The height of the patterns is 500 nm. The DLC molds were used to form the insulating layer of polysiloxane in RTC-NCL. We carried out the RTC-NCL process using the DLC mold under the following optimum conditions: 0.1 MPa-pressure for coating DLC mold with polysiloxane film, 2.1 MPa-pressure for transferring polysiloxane from DLC mold pattern to indium tin oxide (ITO) glass substrate. We deposited N, N'-Diphenyl -N, N'-di (m-tolyl)benzidine (TPD) [40 nm-thickness] as hole transport layer / Tris(8-quinolinolato)aluminum (Alq3) [40 nm-thickness] as electron transport layer / Al [200 nm-thickness] as cathode on ITO glass substrateas anode in this order. We succeeded in formation of the insulating layer with square and rectangle dots which has 10 µm-width,10 µm-width and 50 µm-length, and operation of micro-OLEDs by RTC-NIL using DLC molds.

Micro-organic Light-emitting Devices Fabricated by Room-temperature Curing Nanoimprint Lithography Using Diamond Molds

2012 ◽  
Vol 1395 ◽  
Author(s):  
Ippei Ishikawa ◽  
Taisuke Okuno ◽  
Shuji Kiyohara ◽  
Yoshio Taguchi ◽  
Yoshinari Sugiyama ◽  
...  
Keyword(s):  
Nanoimprint Lithography ◽  
Room Temperature ◽  
Hole Transport ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Insulating Layer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light ◽  
Organic Light Emitting Devices

ABSTRACTOrganic light-emitting devices (OLEDs) have attracted a lot of attention as a next generation display. In this study, we fabricated the micro-OLEDs by room-temperature curing nanoimprint lithography (RTC-NIL) using diamond molds. The diamond has superior durability and was used as mold material for RTC-NIL. The diamond molds have been fabricated by electron cyclotron resonance (ECR) oxygen ion shower with polysiloxane oxide mask in the electron beam (EB) lithography technology. We fabricated the diamond mold pattern with 10 μm-square dot. The diamond molds have been used to form an insulating layer in micro-OLEDs. The optimum thickness of N,N’-Diphenyl-N,N’-di(m-tolyl)benzidine (TPD) [hole transport layer],Tris(8-quinolinolato)aluminum (Alq3) [electron transport layer] and aluminum (Al) [cathode] were 40 nm, 40 nm and 200 nm, respectively. We succeeded in formation of insulating layer in micro-OLEDs and operation of micro-OLEDs with 10 μm-square-dot by RTC-NIL using diamond molds.

All inorganic quantum dot light emitting devices with solution processed metal oxide transport layers

MRS Advances ◽  
2016 ◽  
Vol 1 (4) ◽  
pp. 305-310 ◽  
Author(s):  
R. Vasan ◽  
H. Salman ◽  
M. O. Manasreh
Keyword(s):  
Electron Transport ◽  
Quantum Dot ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Hole Transport ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Light Emitting Devices

ABSTRACTAll inorganic quantum dot light emitting devices with solution processed transport layers are investigated. The device consists of an anode, a hole transport layer, a quantum dot emissive layer, an electron transport layer and a cathode. Indium tin oxide coated glass slides are used as substrates with the indium tin oxide acting as the transparent anode electrode. The transport layers are both inorganic, which are relatively insensitive to moisture and other environmental factors as compared to their organic counterparts. Nickel oxide acts as the hole transport layer, while zinc oxide nanocrystals act as the electron transport layer. The nickel oxide hole transport layer is formed by annealing a spin coated layer of nickel hydroxide sol-gel. On top of the hole transport layer, CdSe/ZnS quantum dots synthesized by hot injection method is spin coated. Finally, zinc oxide nanocrystals, dispersed in methanol, are spin coated over the quantum dot emissive layer as the electron transport layer. The material characterization of different layers is performed by using absorbance, Raman scattering, XRD, and photoluminescence measurements. The completed device performance is evaluated by measuring the IV characteristics, electroluminescence and quantum efficiency measurements. The device turn on is around 4V with a maximum current density of ∼200 mA/cm2 at 9 V.

Investigation of a Novel Light-blue-emitting Fluorescent Guest/Host System with Excellent Lifetime

2006 ◽  
Vol 916 ◽  
Author(s):  
Philipp van Gemmern ◽  
Stefan P. Grabowski ◽  
Herbert Boerner ◽  
Volker van Elsbergen ◽  
Hans-Peter Löbl ◽  
...  
Keyword(s):  
Hole Transport ◽  
Transport Layer ◽  
Constant Current ◽  
Electron Transport Layer ◽  
Hole Transport Layer ◽  
Charge Balance ◽  
Light Emitting ◽  
Host System ◽  
Light Emitting Devices ◽  
Organic Light

AbstractIn this work, organic light emitting devices (OLEDs) based on a blue-emitting fluorescent guest/host-system from Merck OLED Materials GmbH is investigated. OLEDs comprising a hole transport layer (HTL), the emissive film Merck Blue Host:Merck Blue Guest (MBH:MBG), a hole-blocking film and the electron transport layer (ETL) were prepared by vacuum thermal evaporation. The hole-blocking capabilities of aluminum(III)bis(2-methyl-8-quinolinato)4-phenylphenolate (BAlq) and the host material MBH were investigated. By employing an additional HBL, the current efficiency could be increased from 5.7 to 7.4 cd/A. Furthermore, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4-TCNQ) doping of the HTL was investigated. Devices with 4,7-diphenyl-1,10-phenanthroline (BPhen) or 1,3,5-Tris-(N-phenylbenzimidazol-2-yl)benzene (TPBI) as alternative ETLs were fabricated and conclusions were drawn regarding the charge balance in the devices. It was found that employing tris-(8-hydroxyquinoline) aluminum (Alq3) as ETL leads to the best lifetimes of about 2000 hours at a constant current of 20 mA/cm2 while p-doping in combination with BPhen as ETL leads to the highest efficiency of 5.7 lm/W max. and 4.4 lm/W at 1000 cd/m2.

scholarly journals Optimization of the electron transport layer in quantum dot light-emitting devices

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Gary Zaiats ◽  
Shingo Ikeda ◽  
Prashant V. Kamat
Keyword(s):  
Electron Transport ◽  
Quantum Dot ◽  
Charge Carrier ◽  
Hole Transport ◽  
Charge Carriers ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Mobility Of Charge Carriers

AbstractQuantum dot light-emitting devices have emerged as an important technology for display applications. Their emission is a result of recombination between positive and negative charge carriers that are transported through the hole and electron conductive layers, respectively. The selection of electron or hole transport materials in these devices not only demands the alignment of energy levels between the layers but also balances the flow of electrons and holes toward the recombination sites. In this work, we examine a method for device optimization through control of the charge carrier kinetics. We employ impedance spectroscopy to examine the mobility of charge carriers through each of the layers. The derived mobility values provide a path to estimate the transition time of each charge carrier toward the emitting layer. We suggest that an optimal device structure can be obtained when the transition times of both charge carriers toward the active layer are similar. Finally, we examine our hypothesis by focusing on thickness optimization of the electron transport layer.

Electroluminescent Quantum Dot Light-Emitting Diodes with ZnO and MoO3 Carrier Transport Layers

2013 ◽  
Vol 677 ◽  
pp. 98-102 ◽  
Author(s):  
Chun Yuan Huang ◽  
Ping Hua Tsai ◽  
Ying Chih Chen ◽  
Hsin Chieh Yu ◽  
Yan Kuin Su
Keyword(s):  
Quantum Dot ◽  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Sol Gel ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Injection ◽  
Electron Transport Layer ◽  
Device Structure ◽  
Light Emitting

In this article, the quantum dot (QD) light emitting diodes (QDLEDs) with ZnO electron transport layer (ETL) and MoO3hole transport layer (HTL) were demonstrated. The ZnO ETL was fabricated by sol-gel method. To achieve balanced electron and hole injection, hole transport materials including 4,4'-di(N-carbazolyl)biphenyl (CBP) and MoO3were also adapted. The device structure can be simply depicted as indium tin oxide (ITO)/ZnO/Cs2CO3/QD/CBP/MoO3/Au. It was found that the Cs2CO3played an important role to facilitate radiative recombination and reduce the leakage current due to the poor quality of sol-gel fabricated ZnO thin film. Via inserting an annealed Cs2CO3buffer layer with proper thickness, red-emitting QDLEDs with low luminance turn-on voltage of 4.1 V and luminance larger than 100 cd/m2could be obtained. With our demonstration, QDLEDs with ZnO ETL can be a promising device structure for realizing QDLED’s commerizing.

Efficient organic manganese (II) bromide green-light-emitting diodes enabled by manipulating hole and electron transport layer

2021 ◽  
Author(s):  
Hyunsik Im ◽  
Atanu Jana ◽  
Vijaya Gopalan Sree ◽  
QIANKAI BA ◽  
Seong Chan Cho ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Green Light ◽  
Transport Layer ◽  
Lead Free ◽  
Electron Transport Layer ◽  
Flat Panel Displays ◽  
Flat Panel ◽  
Inorganic Hybrid ◽  
Light Emitting ◽  
Light Emitting Devices

Lead-free, non-toxic transition metal-based phosphorescent organic–inorganic hybrid (OIH) compounds are promising for next-generation flat-panel displays and solid-state light-emitting devices. In the present study, we fabricate highly efficient phosphorescent green-light-emitting diodes...

Theoretical Study on Recombination Efficiency at S-DPVBi/Alq3 Interface in OLED

2012 ◽  
Vol 629 ◽  
pp. 44-48
Author(s):  
Young Wook Hwang ◽  
Kwang Sik Kim ◽  
Tae Young Won
Keyword(s):  
Indium Tin Oxide ◽  
Numerical Study ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
The Finite Element Method ◽  
Light Emitting ◽  
Recombination Efficiency ◽  
Interface Barrier ◽  
Recombination Kinetics

In this paper, we report our numerical study on the electrical-optical properties of the organic light emitting diodes (OLEDs) devices with n-doped layer, which is inserted in an effort to reduce the interface barrier between the cathode and the ETL(electron transport layer). In order to anlayze the electrical and optical characteristics such as the transport behavior of carriers, recombination kinetics, and emission property, we undertake the finite element method (FEM) in OLEDs. Our model includes Poisson’s equation, continuity equation to account for behavior of electrons and holes and the exciton continuity/transfer equation to account for recombination of carriers. We employ the multilayer structure that consists of indium tin oxide (ITO); 2, 2’, 7, 7’ –tetrakis (N, N-diphenylamine) - 9, 9’- spirobi-fluorene (S-TAD); 4, 4’- bis (2,2’- diphenylvinyl) - 1,1’- spirobiphenyl (S-DPVBi); tris (8-quinolinolato) aluminium (Alq3); calsium(Ca).

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