Semiconductor Seeded Nanorods with Graded Composition Exhibiting High Quantum-Yield, High Polarization, and Minimal Blinking

Hadar, Ido; Philbin, John P.; Panfil, Yossef E.; Neyshtadt, Shany; Lieberman, Itai; Eshet, Hagai; Lazar, S.; Rabani, Eran; Banin, Uri

doi:10.1021/acs.nanolett.7b00254

Cited by 62 publications

(88 citation statements)

References 36 publications

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“…[107][108][109] An increased biexciton lifetime was observed that correlates with the reduced Auger rate.T he importance of the grading interface was also shown for other dimensionalities,a ss een in CdSe/ Cd 1Àx Zn x S-seeded nanorods with ar adially graded composition that show bright and highly polarized green emission with minimal blinking. [41] These observations provide direct experimental evidence that, in addition to the size of the quantum dot, its interfacial properties also significantly affect the rate of Auger recombination and can be used as an additional parameter for tuning the optical properties of SCNCs for display applications.…”

Section: Fluorescence "Blinking" and Its Suppressionmentioning

confidence: 84%

“…Based on these considerations,i tseems that SCNCs with an alloy composition, such as Zn x Cd 1Àx S, Zn x Cd 1Àx Se,o r CdSe x S 1Àx /Zn x Cd 1Àx Sd ot-in-rod structures, [41] which offer confined potential against the electric field and ar eduction of Auger nonradiative recombination by smoothing the confinement potential, would be the ideal choice for an emitter in an EL QD-LED.I ndeed, relatively high efficiencies in QD-LEDs have been reported with multilayered alloyed structures such as Zn x Cd 1Àx Se/ZnS,Z n x Cd 1Àx Se/ Zn x Cd 1Àx S, and Zn x Cd 1Àx Se. [139,142,155] Recently,Y ang et al reported af ull series of blue,g reen, and red QD-LEDs,a ll with EQE values over 10 %b yu sing graded-shell Cd 1Àx Zn x Se 1Ày S y as well as an ETL of ZnO nanoparticles in "hybrid CTL"a rchitectures.…”

Section: Electroluminescent Displays With Colloidal Scncsmentioning

confidence: 99%

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Colloidal Quantum Nanostructures: Emerging Materials for Display Applications

2018

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Colloidal semiconductor nanocrystals (SCNCs) or, more broadly, colloidal quantum nanostructures constitute outstanding model systems for investigating size and dimensionality effects. Their nanoscale dimensions lead to quantum confinement effects that enable tuning of their optical and electronic properties. Thus, emission color control with narrow photoluminescence spectra, wide absorbance spectra, and outstanding photostability, combined with their chemical processability through control of their surface chemistry leads to the emergence of SCNCs as outstanding materials for present and next‐generation displays. In this Review, we present the fundamental chemical and physical properties of SCNCs, followed by a description of the advantages of different colloidal quantum nanostructures for display applications. The open challenges with respect to their optical activity are addressed. Both photoluminescent and electroluminescent display scenarios utilizing SCNCs are described.

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Section: Fluorescence "Blinking" and Its Suppressionmentioning

confidence: 84%

Section: Electroluminescent Displays With Colloidal Scncsmentioning

confidence: 99%

Colloidal Quantum Nanostructures: Emerging Materials for Display Applications

2018

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“…Nanoscale heterostructures which incorporate two or more materials such as in core–shell nanocrystals, core‐crown nanoplates, or seeded nanorods, allow better control of the optical, electrical, and magnetic phenomena that is inaccessible in single component nanoparticles. In NPL heterostructures, the most attractive features are the possibility of a spatial separation of holes and electrons in core–shell NPLs, and efficient exciton collection and rapid transfer to the core in core‐crown NPLs .…”

Section: Resultsmentioning

confidence: 99%

Chiral 2D Colloidal Semiconductor Quantum Wells

Yang

Kazes

Oron

2018

Adv Funct Materials

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Induced chirality in colloidal semiconductor nanoparticles has raised significant attention in the past few years as an extremely sensitive spectroscopic tool and due to the promising applications of chiral quantum dots in sensing, quantum optics, and spintronics. Yet, the origin of the induced chiroptical effects in semiconductor nanoparticles is still not fully understood, partly because almost all the theoretical and experimental studies to date are based on the simple model system of a spherical nanocrystal. Here, the realization of induced chirality in atomically flat 2D colloidal quantum wells is shown. A strong circular dichroism (CD) response as well as an absorptive-like CD line shape is observed in chiral CdSe nanoplatelets (NPLs), significantly differing from that previously observed in spherical dots. Furthermore, this intense CD signal almost completely disappears after coating with a very thin CdS shell. In contrast, CdSe-CdS core-crown NPLs exhibit a spectral response which seems to originate independently from the core and the crown regions of the NPL. This work on the one hand further advances the understanding of the fundamental origin of induced chiroptical effects in semiconductor nanoparticles, and on the other opens a pathway toward applications using chiroptical materials.

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“…The optical density of QRs in the film was measured as 1.2 at 460 nm. The QRs used in this study showed PL quantum yield of 70% which is lower than the ones in some recently published reports . Such films fabricated with QRs having much higher PL quantum yield and increased polarization ratio are expected to enhance the optical efficiency of the LCD device up to 7% .…”

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confidence: 66%

Functional Film with Electric‐Field‐Aided Aligned Assembly of Quantum Rods for Potential Application in Liquid Crystal Display

Kaur

Murali

Manda

et al. 2018

Advanced Optical Materials

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conquered the large-area display market owing to its advantages such as higher resolution and longer lifetime, but faced challenges from OLED devices in terms of module thickness, response time, and vivid colors. [1] The traditional LCD technology uses blue light-emitting diodes (LEDs) coupled with a yellow phosphor to originate a white light which is transmitted through an assembly of devices comprising polarizers, thin-film transistor array, liquid crystals, and color filters. [2] However, the wide transmission through the color filters and broad emission spectrum of yellow phosphor practically inhibits the realization of wider color gamut in such LCD devices. [3] Semiconductor quantum rods (QRs), owing to their higher brightness, [4] color purity, [5] and polarized light emission [6] features, are lending prominent prospects for their application in display technology. The use of quantum dots in the backlight unit in the form of quantum-dot enhancement film has already been demonstrated [7] ; however, the emission from these spherical particles is isotropic. A unidirectional aligned array of QRs coupled with LCD backlight can be foreseen as a viable option to attain wider color gamut and light polarization. [8] A polarized blue light coming from either laminated conventional polarizer or in-cell coated polarizer can stimulate the QRs to provide narrow red and green polarized emission (Figure 1). This can result in reduced color crosstalk, and hence LCD with high color gamut and contrast ratio can be realized.The alignment of QRs is crucial to attain maximum polarized light emission. Several approaches have been demonstrated in the past on this pathway such as by utilizing photoalignment technology, [9] mechanical rubbing, [10] assembly in liquid crystal defects, [11] and solvent evaporation-assisted assembly. [12] Furthermore, QRs embedded in nanofibers sheets using electrospinning [13] and mechanical stretching of polymer film [14] have been reported with higher degree of alignment. The use of external electric field has been well known to arrange QRs as both parallel [15,16] and perpendicular [17] to the substrate. Herein, we report a simplistic approach for unidirectional alignment of CdSe/CdS QRs by utilizing external electric field after mixing in solvent-based reactive mesogen (RM). The QRs showed higher Harnessing the unique polarized light emission characteristic from semiconductor quantum rods (QRs) necessitates their large-area unidirectional alignment. Herein, the aligned assembly of CdSe/CdS QRs is demonstrated by fabricating a functional film on a micrometer-spaced interdigitated electrodes substrate over an area of ≈1.3 cm 2 . The external electric field is used to control the position and orientation of QRs which is later frozen by the polymerization of reactive mesogen under the exposure of UV light.Under the fluorescence microscope, a judicious change in the QRs emission intensity with the polarizer axis positioned parallel and perpendicular to the alignment direction suggests the optica...

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Semiconductor Seeded Nanorods with Graded Composition Exhibiting High Quantum-Yield, High Polarization, and Minimal Blinking

Cited by 62 publications

References 36 publications

Colloidal Quantum Nanostructures: Emerging Materials for Display Applications

Colloidal Quantum Nanostructures: Emerging Materials for Display Applications

Chiral 2D Colloidal Semiconductor Quantum Wells

Functional Film with Electric‐Field‐Aided Aligned Assembly of Quantum Rods for Potential Application in Liquid Crystal Display

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