Special Issue "Quantum Dots and Micro-LED Display"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (31 October 2020).

Special Issue Editors

Prof. Dr. Hao-chung Kuo
Website
Guest Editor
Department of Photonics & Institute of Electro-Optical Engineering, National Chiao-Tung University, Hsinchu, Taiwan
Interests: Nanostructured optoelectronic materials and devices; III-V (Nitride) high speed semiconductor laser technology and related research
Special Issues and Collections in MDPI journals
Prof. Dr. Lung-Chien Chen
Website
Co-Guest Editor
Department of Electro-optical Engineering, National Taipei University of Technology, Taiwan
Interests: ultraviolet epitaxy; semiconductor optoelectronic components; semiconductor materials
Special Issues and Collections in MDPI journals
Prof. Dr. Zhaojun Liu
Website
Co-Guest Editor
Southern University of Science and Technology, Department of Electrical and Electronic Engineering, Qingshuihe, Shenzhen, China
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Quantum dots (QDs) have many unique physical and optical properties, such as high photoluminescence quantum yield, tunable emission over the entire visible spectral region, narrow emission spectrum, and high color purity. QDs have become a suitable candidate material in the display field, which has great potential to replace the traditional phosphor powder and increase the LCD color gamut range.

Micro-LED is an emerging flat panel display technology. As the name implies, micro LED displays consist of arrays of microscopic LEDs forming the individual pixel elements. The applications include near-eye display, wearable devices, head mount devices, visible light communications, computer monitors, biomedical devices and projectors, which are benefit from the obvious advantages of Micro-LED display in brightness and saturation, high display quality even in high-intensity ambient light.

In this Special Issue, we would like to invite all papers related science and technologies of Quantum Dot (QD) ranging from materials research, device structure and properties, device applications for micro-LED display, manufacturing and high color gamut of display using QD. Especially, in the following fields:

  • QD or Micro-LED display
  • Energy applications
  • Bio-applications
  • Mechanical resonators
  • Optoelectronics like lasing, lighting, micro-display, AR/VR etc.

Prof. Dr. Hao-chung Kuo
Prof. Dr. Lung-Chien Chen
Prof. Dr. Zhaojun Liu
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Nanomateria
  • Perovskite quantum dots
  • IR quantum dots
  • microled display

Published Papers (10 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle
Dependence of Photoresponsivity and On/Off Ratio on Quantum Dot Density in Quantum Dot Sensitized MoS2 Photodetector
Nanomaterials 2020, 10(9), 1828; https://doi.org/10.3390/nano10091828 - 14 Sep 2020
Abstract
Non-radiative energy transfer (NRET) from quantum dots (QDs) to monolayer MoS2 has been shown to greatly enhance the photoresponsivity of the MoS2 photodetector, lifting the limitations imposed by monolayer absorption thickness. Studies were often performed on a photodetector with a channel [...] Read more.
Non-radiative energy transfer (NRET) from quantum dots (QDs) to monolayer MoS2 has been shown to greatly enhance the photoresponsivity of the MoS2 photodetector, lifting the limitations imposed by monolayer absorption thickness. Studies were often performed on a photodetector with a channel length of only a few μm and an active area of a few μm2. Here, we demonstrate a QD sensitized monolayer MoS2 photodetector with a large channel length of 40 μm and an active area of 0.13 mm2. The QD sensitizing coating greatly enhances photoresponsivity by 14-fold at 1.3 μW illumination power, as compared with a plain monolayer MoS2 photodetector without QD coating. The photoresponsivity enhancement increases as QD coating density increases. However, QD coating also causes dark current to increase due to charge doping from QD on MoS2. At low QD density, the increase of photocurrent is much larger than the increase of dark current, resulting in a significant enhancement of the signal on/off ratio. As QD density increases, the increase of photocurrent becomes slower than the increase of dark current. As a result, photoresponsivity increases, but the on/off ratio decreases. This inverse dependence on QD density is an important factor to consider in the QD sensitized photodetector design. Full article
(This article belongs to the Special Issue Quantum Dots and Micro-LED Display)
Show Figures

Figure 1

Open AccessArticle
Comparative Chemico-Physical Analyses of Strain-Free GaAs/Al0.3Ga0.7As Quantum Dots Grown by Droplet Epitaxy
Nanomaterials 2020, 10(7), 1301; https://doi.org/10.3390/nano10071301 - 02 Jul 2020
Cited by 3
Abstract
We investigate the quantum confinement effects on excitons in several types of strain-free GaAs/Al 0.3 Ga 0.7 As droplet epitaxy (DE) quantum dots (QDs). By performing comparative analyses of energy-dispersive X-ray spectroscopy with the aid of a three-dimensional (3D) envelope-function model, we elucidate [...] Read more.
We investigate the quantum confinement effects on excitons in several types of strain-free GaAs/Al 0.3 Ga 0.7 As droplet epitaxy (DE) quantum dots (QDs). By performing comparative analyses of energy-dispersive X-ray spectroscopy with the aid of a three-dimensional (3D) envelope-function model, we elucidate the individual quantum confinement characteristics of the QD band structures with respect to their composition profiles and the asymmetries of their geometrical shapes. By precisely controlling the exciton oscillator strength in strain-free QDs, we envisage the possibility of tailoring light-matter interactions to implement fully integrated quantum photonics based on QD single-photon sources (SPSs). Full article
(This article belongs to the Special Issue Quantum Dots and Micro-LED Display)
Show Figures

Graphical abstract

Open AccessArticle
Investigation of Electrical Properties and Reliability of GaN-Based Micro-LEDs
Nanomaterials 2020, 10(4), 689; https://doi.org/10.3390/nano10040689 - 06 Apr 2020
Abstract
In this paper, we report high-performance Micro-LEDs on sapphire substrates, with pixel size scaling to 20 µm and an ultra-high current density of 9902 A/cm2. The forward voltages (VF) of the devices ranged from 2.32 V to 2.39 V [...] Read more.
In this paper, we report high-performance Micro-LEDs on sapphire substrates, with pixel size scaling to 20 µm and an ultra-high current density of 9902 A/cm2. The forward voltages (VF) of the devices ranged from 2.32 V to 2.39 V under an injection current density of 10 A/cm2. The size and structure-dependent effects were subsequently investigated to optimize the device design. The reliability of Micro-LED devices was evaluated under long-aging, high-temperature, and high-humidity conditions. It was found that Micro-LED devices can maintain comparable performance with an emission wavelength of about 445 nm and a full width at half maximum (FWHM) of 22 nm under extreme environments. Following this, specific analysis with four detailed factors of forward voltage, forward current, slope, and leakage current was carried out in order to show the influence of the different environments on different aspects of the devices. Full article
(This article belongs to the Special Issue Quantum Dots and Micro-LED Display)
Show Figures

Figure 1

Open AccessArticle
Yb:MoO3/Ag/MoO3 Multilayer Transparent Top Cathode for Top-Emitting Green Quantum Dot Light-Emitting Diodes
Nanomaterials 2020, 10(4), 663; https://doi.org/10.3390/nano10040663 - 02 Apr 2020
Abstract
In this study, we report on the application of a dielectric/ultra-thin metal/dielectric (DMD) multilayer consisting of ytterbium (Yb)-doped molybdenum oxide (MoO3)/silver (Ag)/MoO3 stacked as the transparent cathode in top-emitting green quantum dot light-emitting diodes (QLED). By optimizing the Yb doping [...] Read more.
In this study, we report on the application of a dielectric/ultra-thin metal/dielectric (DMD) multilayer consisting of ytterbium (Yb)-doped molybdenum oxide (MoO3)/silver (Ag)/MoO3 stacked as the transparent cathode in top-emitting green quantum dot light-emitting diodes (QLED). By optimizing the Yb doping ratio, we have highly improved the electron injection ability from 0.01 to 0.35. In addition, the dielectric/ultra-thin metal/dielectric (DMD) cathode also shows a low sheet resistance of only 12.2 Ω/sq, which is superior to the resistance of the commercially-available indium tin oxide (ITO) electrode (~15 Ω/sq). The DMD multilayer exhibits a maximum transmittance of 75% and an average transmittance of 70% over the visible range of 400–700 nm. The optimized DMD-based G-QLED has a smaller current leakage at low driving voltage. The optimized DMD-based G-QLED enhances the current density than that of G-QLED with indium zinc oxide (IZO) as a cathode. The fabricated DMD-based G-QLED shows a low turn-on voltage of 2.2 V, a high current efficiency of 38 cd/A, and external quantum efficiency of 9.8. These findings support the fabricated DMD multilayer as a promising cathode for transparent top-emitting diodes. Full article
(This article belongs to the Special Issue Quantum Dots and Micro-LED Display)
Show Figures

Figure 1

Open AccessArticle
Spray Coated Colloidal Quantum Dot Films for Broadband Photodetectors
Nanomaterials 2019, 9(12), 1738; https://doi.org/10.3390/nano9121738 - 06 Dec 2019
Cited by 1
Abstract
A technique for scalable spray coating of colloidal CdSeTe quantum dots (QDs) for photovoltaics and photodetector applications is presented. A mixture solvent with water and ethanol was introduced to enhance the adhesive force between QDs and the substrate interface. The performance of the [...] Read more.
A technique for scalable spray coating of colloidal CdSeTe quantum dots (QDs) for photovoltaics and photodetector applications is presented. A mixture solvent with water and ethanol was introduced to enhance the adhesive force between QDs and the substrate interface. The performance of the detector reached the highest values with 40 spray coating cycles of QD deposition. The photodetectors without bias voltage showed broadband response in the wavelength range of 300–800 nm, and high responsivity of 15 mA/W, detectivity of more than 1011 Jones and rise time of 0.04 s. A large size QD-logo pattern film (10 × 10 cm2) prepared by the spray coating process displayed excellent uniformity of thickness and absorbance. The large area detectors (the active area 1 cm2) showed almost the same performance as the typical laboratory-size ones (the active area 0.1 cm2). Our study demonstrates that the spray coating is a very promising film fabrication technology for the industrial-scale production of optoelectronic devices. Full article
(This article belongs to the Special Issue Quantum Dots and Micro-LED Display)
Show Figures

Graphical abstract

Open AccessArticle
Influence of Annealing Temperature on Weak-Cavity Top-Emission Red Quantum Dot Light Emitting Diode
Nanomaterials 2019, 9(11), 1639; https://doi.org/10.3390/nano9111639 - 19 Nov 2019
Cited by 2
Abstract
In this report, we show that the annealing temperature in QDs/Mg-doped ZnO film plays a very important role in determining QLEDs performance. Measurements of capacitance and single carrier device reveal that the change of the device efficiency with different annealing temperatures is related [...] Read more.
In this report, we show that the annealing temperature in QDs/Mg-doped ZnO film plays a very important role in determining QLEDs performance. Measurements of capacitance and single carrier device reveal that the change of the device efficiency with different annealing temperatures is related to the balance of both electron and hole injection. A comparison of annealing temperatures shows that the best performance is demonstrated with 150 °C-annealing temperature. With the improved charge injection and charge balance, a maximum current efficiency of 24.81 cd/A and external quantum efficiency (EQE) of 20.09% are achievable in our red top-emission QLEDs with weak microcavity structure. Full article
(This article belongs to the Special Issue Quantum Dots and Micro-LED Display)
Show Figures

Figure 1

Open AccessArticle
Ultrawide Color Gamut Perovskite and CdSe/ZnS Quantum-Dots-Based White Light-Emitting Diode with High Luminous Efficiency
Nanomaterials 2019, 9(9), 1314; https://doi.org/10.3390/nano9091314 - 14 Sep 2019
Cited by 6
Abstract
We demonstrate excellent color quality of liquid-type white light-emitting diodes (WLEDs) using a combination of green light-emitting CsPbBr3 and red light-emitting CdSe/ZnS quantum dots (QDs). Previously, we reported red (CsPbBr1.2I1.8) and green (CsPbBr3) perovskite QDs (PQDs)-based [...] Read more.
We demonstrate excellent color quality of liquid-type white light-emitting diodes (WLEDs) using a combination of green light-emitting CsPbBr3 and red light-emitting CdSe/ZnS quantum dots (QDs). Previously, we reported red (CsPbBr1.2I1.8) and green (CsPbBr3) perovskite QDs (PQDs)-based WLEDs with high color gamut, which manifested fast anion exchange and stability issues. Herein, the replacement of red PQDs with CdSe/ZnS QDs has resolved the aforementioned problems effectively and improved both stability and efficiency. Further, the proposed liquid-type device possesses outstanding color gamut performance (132% of National Television System Committee and 99% of Rec. 2020). It also shows a high efficiency of 66 lm/W and an excellent long-term operation stability for over 1000 h. Full article
(This article belongs to the Special Issue Quantum Dots and Micro-LED Display)
Show Figures

Figure 1

Open AccessArticle
A Bilayer 2D-WS2/Organic-Based Heterojunction for High-Performance Photodetectors
Nanomaterials 2019, 9(9), 1312; https://doi.org/10.3390/nano9091312 - 13 Sep 2019
Cited by 2
Abstract
Two-dimensional (2D) tungsten disulfide (WS2) has inspired great efforts in optoelectronics, such as in solar cells, light-emitting diodes, and photodetectors. However, chemical vapor deposition (CVD) grown 2D WS2 domains with the coexistence of a discontinuous single layer and multilayers are [...] Read more.
Two-dimensional (2D) tungsten disulfide (WS2) has inspired great efforts in optoelectronics, such as in solar cells, light-emitting diodes, and photodetectors. However, chemical vapor deposition (CVD) grown 2D WS2 domains with the coexistence of a discontinuous single layer and multilayers are still not suitable for the fabrication of photodetectors on a large scale. An emerging field in the integration of organic materials with 2D materials offers the advantages of molecular diversity and flexibility to provide an exciting aspect on high-performance device applications. Herein, we fabricated a photodetector based on a 2D-WS2/organic semiconductor materials (mixture of the (Poly-(N,N′-bis-4-butylphenyl-N,N′-bisphenyl) benzidine and Phenyl-C61-butyric acid methyl ester (Poly-TPD/PCBM)) heterojunction. The application of Poly-TPD/PCBM organic blend film enhanced light absorption, electrically connected the isolated WS2 domains, and promoted the separation of electron-hole pairs. The generated exciton could sufficiently diffuse to the interface of the WS2 and the organic blend layers for efficient charge separation, where Poly-TPD was favorable for hole carrier transport and PCBM for electron transport to their respective electrodes. We show that the photodetector exhibited high responsivity, detectivity, and an on/off ratio of 0.1 A/W, 1.1 × 1011 Jones, and 100, respectively. In addition, the photodetector showed a broad spectral response from 500 nm to 750 nm, with a peak external quantum efficiency (EQE) of 8%. Our work offers a facile solution-coating process combined with a CVD technique to prepare an inorganic/organic heterojunction photodetector with high performance on silicon substrate. Full article
(This article belongs to the Special Issue Quantum Dots and Micro-LED Display)
Show Figures

Figure 1

Review

Jump to: Research

Open AccessReview
The Stability of Metal Halide Perovskite Nanocrystals—A Key Issue for the Application on Quantum-Dot-Based Micro Light-Emitting Diodes Display
Nanomaterials 2020, 10(7), 1375; https://doi.org/10.3390/nano10071375 - 15 Jul 2020
Cited by 3
Abstract
The metal halide perovskite nanocrystal (MHP-NC), an easy-to-fabricate and low cost fluorescent material, is recognized to be among the promising candidates of the color conversion material in the micro light-emitting diode (micro-LED) display, providing that the stability can be further enhanced. It is [...] Read more.
The metal halide perovskite nanocrystal (MHP-NC), an easy-to-fabricate and low cost fluorescent material, is recognized to be among the promising candidates of the color conversion material in the micro light-emitting diode (micro-LED) display, providing that the stability can be further enhanced. It is found that the water steam, oxygen, thermal radiation and light irradiation—four typical external factors in the ambient environment related to micro-LED display—can gradually alter and destroy the crystal lattice. Despite the similar phenomena of photoluminescence quenching, the respective encroaching processes related to these four factors are found to be different from one another. The encroaching mechanisms are collected and introduced in separate categories with respect to each external factor. Thereafter, a combined effect of these four factors in an environment mimicking real working conditions of micro-LED display are also introduced. Finally, recent progress on the full-color application of MHP-NC is also reviewed in brief. Full article
(This article belongs to the Special Issue Quantum Dots and Micro-LED Display)
Show Figures

Figure 1

Open AccessReview
Advances in Quantum-Dot-Based Displays
Nanomaterials 2020, 10(7), 1327; https://doi.org/10.3390/nano10071327 - 06 Jul 2020
Cited by 2
Abstract
In terms of their use in displays, quantum dots (QDs) exhibit several advantages, including high illumination efficiency and color rendering, low-cost, and capacity for mass production. Furthermore, they are environmentally friendly. Excellent luminescence and charge transport properties of QDs led to their application [...] Read more.
In terms of their use in displays, quantum dots (QDs) exhibit several advantages, including high illumination efficiency and color rendering, low-cost, and capacity for mass production. Furthermore, they are environmentally friendly. Excellent luminescence and charge transport properties of QDs led to their application in QD-based light-emitting diodes (LEDs), which have attracted considerable attention in display and solid-state lighting applications. In this review, we discuss the applications of QDs which are used on color conversion filter that exhibit high efficiency in white LEDs, full-color micro-LED devices, and liquid-type structure devices, among others. Furthermore, we discuss different QD printing processes and coating methods to achieve the full-color micro-LED. With the rise in popularity of wearable and see-through red, green, and blue (RGB) full-color displays, the flexible substrate is considered as a good potential candidate. The anisotropic conductive film method provides a small controllable linewidth of electrically conductive particles. Finally, we discuss the advanced application for flexible full-color and highly efficient QD micro-LEDs. The general conclusion of this study also involves the demand for a more straightforward QD deposition technique, whose breakthrough is expected. Full article
(This article belongs to the Special Issue Quantum Dots and Micro-LED Display)
Show Figures

Figure 1

Back to TopTop