Characteristics of CuInS2/ZnS quantum dots and its application on LED

Kim, Hyunki; Han, Jeong‐Won; Kang, Dong Seok; Kim, Sung Wook; Jang, Dong Seon; Suh, Minwon; Kirakosyan, Artavazd; Jeon, Duk Young

doi:10.1016/j.jcrysgro.2011.01.059

Cited by 81 publications

(59 citation statements)

References 7 publications

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“…43 The PLQY of the QDs was determined by comparing the total emission intensity of the QDs with that of rhodamine 6G at an excitation wavelength of 500 nm. During the ZnS passivation step, the size of the effective CIS core is reduced through the surface etching of the CIS core 30,48 or by the formation of an alloyed interfacial CIS/ZnS shell layer, 19,35,55 which can cause a blue shi of the absorption and emission peaks. Previous studies showed that a Cu-rich composition resulted in a low level of uorescence emission; 8,19,23 however, in the present work, it was found that the PLQY of the CIS QDs was not signicantly dependent on the Cu/ In ratio as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Highly luminescent, off-stoichiometric Cu_xIn_yS₂/ZnS quantum dots for near-infrared fluorescence bio-imaging

et al. 2015

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Quantum dots (QDs) are very attractive for in vivo bio-imaging and therapeutic applications due to their relatively large absorption coefficient, high quantum yield, low level of photo bleaching, and large Stokes shift. However, two technical issues need to be resolved before they can be practically applied to in vivo bio-imaging applications: ensuring both reduced toxicity and efficient emission in the near-infrared (NIR) frequency range. Here we report a simple and reliable method to synthesize highly luminescent, NIRemitting Cu x In y S 2 /ZnS (CIS/ZnS) core-shell QDs for deep-tissue bio imaging applications. Offstoichiometric effects are utilized with 1-dodecanethiol as a reaction medium for thermolytic synthesis.The most important finding in our work is that at a high Cu/In ratio, the emission spectrum of CIS/ZnS QDs can be tuned to NIR frequencies with a high quantum yield up to approximately 65%. The maximum emission wavelengths of the synthesized QDs are 589 nm (QD 589 ) and 726 nm (QD 726 ) at a Cu/In ratio of 0.25 and of 1.8, respectively. Their feasibility for optical bio-imaging in a deep-tissue condition is investigated by the intramuscular injection of QD-loaded polymer microspheres in a mouse model. Our results show that more than 30% of the original emission of the QD 726 can be detected through biological tissue of 0.9 cm, whereas emission from the QD 589 is not detectable. Our investigation on the offstoichiometric effects of CIS QDs will contribute to the development of highly luminescent, NIR-emitting, cadmium-free QDs in the areas of tissue-level imaging, sensing, and therapeutics. † Electronic supplementary information (ESI) available: Size distribution histograms of the CIS QDs (Fig. S1); comparison of PLQY with a previous work (Fig. S2); the original curve of absorption spectra of the CIS QDs (Fig. S3); size distribution histograms of the CIS/ZnS QDs (Fig. S4); SEM images of the QD-loaded PMMA microspheres (Fig. S5). See

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Section: Resultsmentioning

confidence: 99%

Highly luminescent, off-stoichiometric Cu_xIn_yS₂/ZnS quantum dots for near-infrared fluorescence bio-imaging

et al. 2015

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“…This value is comparable to the previous research results on the luminous efficacy (10.7 lm/W) of LED fabricated using CuInS 2 /ZnS QD nanocrystals. 35 Figure 15(a) contains the emission spectra of white LEDs fabricated with the polymeric microspheres containing CdSe@ZnS QD nanocrystals. The measurements were performed just after lighting the LED devices and after 540 minutes (9 hours) from the initial lighting.…”

Section: Fabrication Of White Leds Using Composite Colloidal Particlementioning

confidence: 99%

Quantum-dot-embedded colloidal polymeric particles for white light-emitting-diode with high color rendering index

Cho¹,

Kim²,

Kim³

et al. 2013

Mat Express

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We report on the simple colloidal encapsulation of quantum dots into polymeric microspheres using oil-in-water emulsions, which was generated by ultrasound emulsification method. Poly(styrene-co-methylmethacrylate) and Cd(S, Se) or CdSe@ZnS nanoparticles were dissolved in toluene and emulsified into water with surfactant. Then, oil phase inside emulsions was slowly evaporated producing composite microspheres of polymer and quantum dots. Their size could be controlled well by either varying the concentration of polymers in emulsion phase or adjusting the size of emulsion droplets. Finally, quantum-dot-embedded polymeric microspheres were deposited on the blue LED chips which showed white colors with high value of color rendering index.

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“…As one of the most important II-IV semiconductors, ZnS has found in many applications like fluorescence probe4, phosphors [5][6] , pharmaceutics [7][8] , Light Emitting Diode (LED) 9 , electroluminescenc 10 and non-linear optical devices 11 . Synthesis temperature has an important role in controlling particle shape and size 12 .…”

Section: Introductionmentioning

confidence: 99%

Temperature dependent Synthesis of Zinc Sulfide Nanocrystals

Bera¹,

Saha²,

Jana³

2018

Orient. J. Chem

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Chemical reduction route is preferred to prepare ZnS semiconductor nanoparticles at three different temperatures without any subsequent heat treatment. The grown nanoparticles are investigated using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) Spectroscopy, Ultraviolet-Visible (UV-Vis) Absorption and Photoluminescence (PL) spectroscopy for structural and optical analysis. From the investigation, it is seen that the crystal size appears to increase with an increase in synthesis temperature. The cubic crystal structure is shown in XRD analysis. The UV-Vis spectrum shows the increase in the band gap which supports quantum confinement effect. The PL spectrum of ZnS nanocrystals displays a visible violet spectrum. The FTIR spectra determine the absorbance and nature of bonds present in samples.

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Characteristics of CuInS2/ZnS quantum dots and its application on LED

Cited by 81 publications

References 7 publications

Highly luminescent, off-stoichiometric Cu_xIn_yS₂/ZnS quantum dots for near-infrared fluorescence bio-imaging

Highly luminescent, off-stoichiometric Cu_xIn_yS₂/ZnS quantum dots for near-infrared fluorescence bio-imaging

Quantum-dot-embedded colloidal polymeric particles for white light-emitting-diode with high color rendering index

Temperature dependent Synthesis of Zinc Sulfide Nanocrystals

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Characteristics of CuInS2/ZnS quantum dots and its application on LED

Cited by 81 publications

References 7 publications

Highly luminescent, off-stoichiometric CuxInyS2/ZnS quantum dots for near-infrared fluorescence bio-imaging

Highly luminescent, off-stoichiometric CuxInyS2/ZnS quantum dots for near-infrared fluorescence bio-imaging

Quantum-dot-embedded colloidal polymeric particles for white light-emitting-diode with high color rendering index

Temperature dependent Synthesis of Zinc Sulfide Nanocrystals

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Product

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Highly luminescent, off-stoichiometric Cu_xIn_yS₂/ZnS quantum dots for near-infrared fluorescence bio-imaging

Highly luminescent, off-stoichiometric Cu_xIn_yS₂/ZnS quantum dots for near-infrared fluorescence bio-imaging