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.

High luminance of CuInS2-based yellow quantum dot light emitting diodes fabricated by all-solution processing

RSC Advances ◽  
2016 ◽  
Vol 6 (76) ◽  
pp. 72462-72470 ◽  
Author(s):  
Jingling Li ◽  
Hu Jin ◽  
Kelai Wang ◽  
Dehui Xie ◽  
Dehua Xu ◽  
...  
Keyword(s):  
Electron Transport ◽  
Quantum Dot ◽  
Zno Nanoparticles ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Hole Transport Layer ◽  
High Luminance ◽  
Light Emitting

In this work, all-solution processed, multi-layer yellow QLEDs, consisting of a hole transport layer of poly(9-vinylcarbazole), emissive layer of ligand exchanged CuInS2/ZnS QDs, and electron transport layer of ZnO nanoparticles, are fabricated.

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.

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.

scholarly journals Improvement of Quantum Dot Light Emitting Device Characteristics by CdSe/ZnS Blended with HMDS (Hexamethyldisilazane)

2020 ◽  
Vol 10 (17) ◽  
pp. 6081
Author(s):  
Junekyun Park ◽  
Eunkyu Shin ◽  
Jongwoo Park ◽  
Yonghan Roh
Keyword(s):  
Quantum Dot ◽  
Photoelectron Spectroscopy ◽  
Surface Defects ◽  
Hole Transport ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Hole Transport Layer ◽  
Atmospheric Conditions ◽  
Light Emitting ◽  
X Ray

We demonstrated the way to improve the characteristics of quantum dot light emitting diodes (QD-LEDs) by adding a simple step to the conventional fabrication process. For instance, we can effectively deactivate the surface defects of quantum dot (QD) (e.g., CdSe/ZnS core-shell QDs in the current work) with the SiO bonds by simply mixing QDs with hexamethyldisilazane (HMDS) under atmospheric conditions. We observed the substantial improvement of device characteristics such that the current efficiency, the maximum luminance, and the QD lifetime were improved by 1.7–1.8 times, 15–18%, and nine times, respectively, by employing this process. Based on the experimental data (e.g., energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS)), we estimated that the growth of the SiOx on the surface of QDs is self-limited: the SiOx are effective to passivate the surface defects of QDs without deteriorating the intrinsic properties including the color-purity of QDs. Second, we proposed that the emission profiling study can lead us to the fundamental understanding of charge flow in each layer of QD-LEDs. Interestingly enough, many problems related to the charge-imbalance phenomenon were simply solved by selecting the combination of thicknesses of the hole transport layer (HTL) and the electron transport layer (ETL).

scholarly journals Significant Enhancement in Quantum-dot Light Emitting Device Stability via a ZnO:Polyethylenimine Mixture in the Electron Transport Layer

2021 ◽  
Author(s):  
Dong Seob Chung ◽  
Tyler Davidson-Hall ◽  
Hyeoghwa Yu ◽  
Fatemeh Samaeifar ◽  
Peter Chun ◽  
...  
Keyword(s):  
Electron Transport ◽  
Quantum Dot ◽  
Transport Layer ◽  
Significant Enhancement ◽  
Electron Transport Layer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Device Stability

The effect of adding polyethylenimine (PEI) into the ZnO electron transport layer (ETL) of inverted quantum dot (QD) light emitting devices (QDLEDs) to form a blended ZnO:PEI ETL instead of...

scholarly journals Correction: 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 ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Light Emitting ◽  
Light Emitting Devices

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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