Multicolored Light-Emitting Diodes Based on All-Quantum-Dot Multilayer Films Using Layer-by-Layer Assembly Method

Bae, Wan Ki; Kwak, Jeonghun; Lim, Jaehoon; Lee, Donggu; Nam, Min Ki; Char, Kookheon; Lee, Changhee; Lee, Seonghoon

doi:10.1021/nl100168s

Cited by 225 publications

(190 citation statements)

References 32 publications

(57 reference statements)

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“…All aqueous solutions were prepared from Milli-Q water (Millipore). The Al 2 Te 3 lumps employed for the generation of H 2 Te were purchased from CERAC Inc. As for the QDs, we either used CdTe, [ 40 ] CdSe/ZnS [ 41 ] with an alloyed gradient shell, or core/shell/shell (CSS) InZnP/ GaP/ZnS [ 42 ] QDs, which were prepared according to previous publications.…”

Section: Methodsmentioning

confidence: 99%

Liquid–Liquid Diffusion‐Assisted Crystallization: A Fast and Versatile Approach Toward High Quality Mixed Quantum Dot‐Salt Crystals

Adam

Wang

Dubavik

et al. 2015

Adv Funct Materials

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2638www.MaterialsViews.com wileyonlinelibrary.com approaches, [ 15,16 ] effi ciency, [ 17,18 ] extending their spectral range [19][20][21] and environmental friendliness using less toxic materials [22][23][24] sparked industrial applications. Those started with the demonstration of a 40 in. display prototype presented by Samsung [ 25 ] and followed by the foundation of QD Vision, Inc., [ 26 ] whose QDs are now used in the latest series of Sony products. All of the mentioned applications require long-term stability of the QDs under various conditions including high temperatures as well as high intensity illumination. Packaging of the QDs within polymer or inorganic matrices is one way to address these issues, while improving the processability of the QDs at the same time. Commonly used polymers, such as polystyrene and poly(methylmethacrylate) [ 27 ] are relatively less stable and tight in comparison to their inorganic counterparts. Inorganic matrices on the other hand can incorporate the QDs directly from their melt, e.g., using the Czochralski approach, [ 28 ] coated as a thin fi lm directly on their surface [ 29,30 ] or, as recently developed by our group, grown as mixed crystals at ambient temperatures from a saturated salt solution. [ 31 ] Using this method, different types of QDs can be incorporated due to the low thermal stress and, by choosing the proper matrix-QD system, the photoluminescence quantum yields (PL-QYs) are enhanced upon incorporation. [ 32,33 ] Here, a new, fast, and versatile method for the incorporation of colloidal quantum dots (QDs) into ionic matrices enabled by liquid-liquid diffusion is demonstrated. QDs bear a huge potential for numerous applications thanks to their unique chemical and physical properties. However, stability and processability are essential for their successful use in these applications. Incorporating QDs into a tight and chemically robust ionic matrix is one possible approach to increase both their stability and processability. With the proposed liquid-liquid diffusion-assisted crystallization (LLDC), substantially accelerated ionic crystallization of the QDs is shown, reducing the crystallization time needed by one order of magnitude. This fast process allows to incorporate even the less stable colloids including initially oil-based ligandexchanged QDs into salt matrices. Furthermore, in a modifi ed two-step approach, the seed-mediated LLDC provides the ability to incorporate oilbased QDs directly into ionic matrices without a prior phase transfer. Finally, making use of their processability, a proof-of-concept white light emitting diode with LLDC-based mixed QD-salt fi lms as an excellent color-conversion layer is demonstrated. These fi ndings suggest that the LLDC offers a robust, adaptable, and rapid technique for obtaining high quality QD-salts.

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Section: Methodsmentioning

confidence: 99%

Liquid–Liquid Diffusion‐Assisted Crystallization: A Fast and Versatile Approach Toward High Quality Mixed Quantum Dot‐Salt Crystals

Adam

Wang

Dubavik

et al. 2015

Adv Funct Materials

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“…The white QLEDs based on randomly mixed QDs have advantages such as easy processing and cost reduction, but the inter-particle energy transfer between QDs of different colors induces low current efficiency, poor EQE, and red-shifted EL. 110 Therefore, the mixing ratio and the mixed structure of the different QDs should be precisely optimized to obtain balanced white EL.…”

Section: Flexible White Qledsmentioning

confidence: 99%

Flexible quantum dot light-emitting diodes for next-generation displays

et al. 2018

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In the future electronics, all device components will be connected wirelessly to displays that serve as information input and/or output ports. There is a growing demand of flexible and wearable displays, therefore, for information input/output of the nextgeneration consumer electronics. Among many kinds of light-emitting devices for these next-generation displays, quantum dot light-emitting diodes (QLEDs) exhibit unique advantages, such as wide color gamut, high color purity, high brightness with low turn-on voltage, and ultrathin form factor. Here, we review the recent progress on flexible QLEDs for the next-generation displays. First, the recent technological advances in device structure engineering, quantum-dot synthesis, and high-resolution full-color patterning are summarized. Then, the various device applications based on cutting-edge quantum dot technologies are described, including flexible white QLEDs, wearable QLEDs, and flexible transparent QLEDs. Finally, we showcase the integration of flexible QLEDs with wearable sensors, micro-controllers, and wireless communication units for the next-generation wearable electronics.

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“…Over the last few years, a variety of solution-based synthesis methods have become available for producing high quality nanocrystals (NCs), either as self-standing colloidal nanoparticles [1][2][3] or as highly controlled crystalline nanophases in suitable host matrices [4][5][6][7] , thus combining the superior resistance of inorganic emitters over organic dyes to degradation with the advantages of inexpensive and large-scale fabrication processes, such as spin coating, contact and ink jet printing and layer-by-layer deposition [8][9][10][11] . Several examples of light-emitting diodes (LEDs) based on nanostructured (NS) materials have been reported by different groups [11][12][13][14] , and have shown a remarkable tunability across the visible spectrum 8,[15][16][17][18] . The extension of the emission into the ultraviolet (UV) region is problematic and increasing efforts are being devoted to this task because of the technological relevance of UV-emitting solution processable nanomaterials 13,[17][18][19][20] .…”

mentioning

confidence: 99%

Fully inorganic oxide-in-oxide ultraviolet nanocrystal light emitting devices

et al. 2012

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The development of integrated photonics and lab-on-a-chip platforms for environmental and biomedical diagnostics demands ultraviolet electroluminescent materials with high mechanical, chemical and environmental stability and almost complete compatibility with existing silicon technology. Here we report the realization of fully inorganic ultraviolet lightemitting diodes emitting at 390 nm with a maximum external quantum efficiency of ~0.3%, based on sno 2 nanoparticles embedded in sio 2 thin films obtained from a solution-processed method. The fabrication involves a single deposition step onto a silicon wafer followed by a thermal treatment in a controlled atmosphere. The fully inorganic architecture ensures superior mechanical robustness and optimal chemical stability in organic solvents and aqueous solutions. The versatility of the fabrication process broadens the possibility of optimizing this strategy and extending it to other nanostructured systems for designed applications, such as active components of wearable health monitors or biomedical devices.

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Multicolored Light-Emitting Diodes Based on All-Quantum-Dot Multilayer Films Using Layer-by-Layer Assembly Method

Cited by 225 publications

References 32 publications

Liquid–Liquid Diffusion‐Assisted Crystallization: A Fast and Versatile Approach Toward High Quality Mixed Quantum Dot‐Salt Crystals

Liquid–Liquid Diffusion‐Assisted Crystallization: A Fast and Versatile Approach Toward High Quality Mixed Quantum Dot‐Salt Crystals

Flexible quantum dot light-emitting diodes for next-generation displays

Fully inorganic oxide-in-oxide ultraviolet nanocrystal light emitting devices

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