Noninjection, one-pot synthesis of Cu-deficient CuInS2/ZnS core/shell quantum dots and their fluorescent properties

Nam, Da-Eun; Song, Woo-Seuk; Yang, Heesun

doi:10.1016/j.jcis.2011.05.058

Cited by 141 publications

(173 citation statements)

References 26 publications

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“…In agreement with previous reports, ZnS shell improved the intensity of absorption and emission [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. The dependence of the PL intensity was no more monotonic; for example, it exhibited a maximum at the synthesis time of about 60 min with improved QY of 65.5%.…”

Section: Shell Synthesissupporting

confidence: 91%

“…The resulting optical properties of CIS QDs were defined as defect emissions [17,35]. The PL emission of CIS/ZnS was studied by several groups as different explanations: Kraatz et al suggested indium-copper antisite (In Cu ″) to valance band emission [36], Nam et al explained that the PL emissions originated from two aspects: In Cu ″ to copper vacancy (V Cu ′) combination and conduction band to V Cu ′ [37]. Hua et al studied the PL properties using steady-state and time-resolved PL spectroscopy analysis and found that the recombination of intrinsic defects inside QDs including donoracceptor emission and a quantized conduction band to defects are the main contribution [26].…”

Section: Introductionmentioning

confidence: 99%

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Optimization of the recipe for the synthesis of CuInS₂/ZnS nanocrystals supported by mechanistic considerations

Luan

et al. 2016

Green Processing and Synthesis

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CuInS 2 /ZnS (CIS/ZnS) quantum dots (QDs) with high photoluminescence (PL) were synthesized via a facile solvothermal approach. Gaussian deconvolution of PL spectra, transmission electron microscopy, and timeresolved PL spectroscopies were used to characterize the emission properties of the prepared CIS and CIS/ZnS QDs. It was found that the growth of ZnS can reduce the surface defect acting as traps to minimize donor-acceptor emissions, and the contribution of band to donor/acceptor transition becomes a dominating emission with the increase of shell growth time. The blue shift of PL emission wavelength of CIS/ZnS QDs underwent two steps: the dramatic blue shift originated from the decreased fraction donor-acceptor transition due to the reduction of surface defects at the beginning and the subsequently mild blueshift with the time from the interdiffusion of CIS and ZnS. The effect of trioctylphosphine (TOP) and dodecanethiol (DDT) as ligands during shell growth on the optical properties of QDs were investigated and compared. The PL quantum yield (QY) of CIS core affects the final value of CIS/ ZnS QDs, and the higher PL QY is achieved while using CIS core with higher PL QY. Based on the selected ligand DDT, the reaction parameters, such as CIS core reaction time, shell growth time, and Zn/Cu feed molar ratio, were further optimized. CIS/ZnS QDs with high PL QY can be obtained with a Zn/Cu feed molar ratio larger than 4, shell growth time of 30 to 90 min, and shell growth temperature 220°C-240°C, and the maximum value was up to about 80% by adjusting the above-mentioned parameters.

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Section: Shell Synthesissupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Optimization of the recipe for the synthesis of CuInS₂/ZnS nanocrystals supported by mechanistic considerations

Luan

et al. 2016

Green Processing and Synthesis

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“…Due to small lattice mismatch (∼2%) between CuInS 2 and ZnS, 24 although they have different crystal structures, it is postulated that ZnS was epitaxially grown on the CIS core, judging from ambiguity of the interface between the CIS core and ZnS shell in the HR-TEM images. The morphologies (nearly sphere for cores and tetrahedral shape for CS and CSS QDs) of the CIS, CIS/ZnS, and CIS/ ZnS/ZnS QDs synthesized with Cu−oleate and In−oleate precursors were similar to those of the previously reported CIS and CIS/ZnS QDs synthesized with CuI and In(CH 3 COO) 3 precursors. 6,15 Formation of ZnS shell on the CIS core was directly verified from energy dispersive spectroscopy (EDS) spectra shown in Figure 2.…”

Section: Acs Applied Materials and Interfacessupporting

confidence: 82%

Highly Bright Yellow-Green-Emitting CuInS₂ Colloidal Quantum Dots with Core/Shell/Shell Architecture for White Light-Emitting Diodes

Park

Hong

Kim

et al. 2015

ACS Appl. Mater. Interfaces

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118

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In this study, we report bright yellow-green-emitting CuInS2 (CIS)-based quantum dots (QDs) and two-band white light-emitting diodes (LEDs) using them. To achieve high quantum efficiency (QE) of yellow-green-emitting CIS QDs, core/shell/shell strategy was introduced to high quality CIS cores (QE = 31.7%) synthesized by using metal-oleate precursors and 1-dodecanethiol. The CIS/ZnS/ZnS QDs showed a high QE of 80.0% and a peak wavelength of 559 nm under the excitation of 450 nm, which is well matched with dominant wavelength of blue LEDs. The formation of core/shell/shell structure was confirmed by X-ray diffraction, transmission electron microscopy, and inductively coupled plasma-optical emission spectroscopy analyses. Intense and broad yellow-green emission band of the CIS/ZnS/ZnS is beneficial for bright two-band white light. When the CIS/ZnS/ZnS was coated on the blue LEDs, the fabricated white LED showed bright natural white light (luminous efficacy (η(L)) = 80.3 lm·W(-1), color rendering index (R(a)) = 73, correlated color temperature (T(c)) = 6140 K). The QD-white LED package showed a high light conversion efficiency of 72.6%. In addition, the CIS/ZnS/ZnS-converted white LED showed relatively stable white light against the variation of forward bias currents of 20-150 mA [color coordinates (x, y) = (0.3320-0.3207, 0.2997-0.2867), R(a) = 70-72, T(c) = 5497-6375 K].

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“…CIS has the advantage of being a ternary material which allows further tuning of optical properties by changing the ratio of Cu and In in the lattice (De Trizio et al 2012;Nam et al 2011;Speranskaya et al 2014;Uehara et al 2008). For example, Cu poor CIS QDs have been shown to have increased PL quantum yield (PLQY) which was blue shifted compared to stoichiometric CIS (Nam et al 2011;Uehara et al 2008;Zhong et al 2012). The chalcopyrite crystal structure of CIS can be considered a superstructure of the zincblende crystal structure of ZnS, where Cu ?…”

Section: Introductionmentioning

confidence: 99%

Structural and optical characterization of CuInS2 quantum dots synthesized by microwave-assisted continuous flow methods

et al. 2015

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Semiconductor quantum dots (QDs) have recently been incorporated into consumer displays and lighting technologies. Now that these materials are being produced on industrial scales, it is important to investigate scalable synthetic methods and less toxic materials and chemistries. To achieve these goals, we have synthesized cadmium-free, visible light-emitting QDs using a microwave-assisted continuous flow reactor. After synthesis, the CuInS 2 QD cores underwent a near-complete Zn cation exchange reaction in a batch reactor, followed by the growth of a ZnS shell. Analysis of X-ray diffraction, transmission electron microscopy, and Raman spectroscopy data indicate that the crystal structure changes from CuInS 2 (chalcopyrite) to ZnS (zincblende) during the cation exchange reaction. Compositional analysis indicated that the core/shell QDs were *98 % ZnS, with Cu and In present at much lower concentrations. The photoluminescence (PL) peak position was blue shifted for longer cation exchange reactions, and it was found that the ZnS shell was necessary for improved PL stability.The synthesized QDs have a PL down conversion efficiency of *65 % when using a blue LED source.

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Noninjection, one-pot synthesis of Cu-deficient CuInS2/ZnS core/shell quantum dots and their fluorescent properties

Cited by 141 publications

References 26 publications

Optimization of the recipe for the synthesis of CuInS₂/ZnS nanocrystals supported by mechanistic considerations

Optimization of the recipe for the synthesis of CuInS₂/ZnS nanocrystals supported by mechanistic considerations

Highly Bright Yellow-Green-Emitting CuInS₂ Colloidal Quantum Dots with Core/Shell/Shell Architecture for White Light-Emitting Diodes

Structural and optical characterization of CuInS2 quantum dots synthesized by microwave-assisted continuous flow methods

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Noninjection, one-pot synthesis of Cu-deficient CuInS2/ZnS core/shell quantum dots and their fluorescent properties

Cited by 141 publications

References 26 publications

Optimization of the recipe for the synthesis of CuInS2/ZnS nanocrystals supported by mechanistic considerations

Optimization of the recipe for the synthesis of CuInS2/ZnS nanocrystals supported by mechanistic considerations

Highly Bright Yellow-Green-Emitting CuInS2 Colloidal Quantum Dots with Core/Shell/Shell Architecture for White Light-Emitting Diodes

Structural and optical characterization of CuInS2 quantum dots synthesized by microwave-assisted continuous flow methods

Contact Info

Product

Resources

About

Optimization of the recipe for the synthesis of CuInS₂/ZnS nanocrystals supported by mechanistic considerations

Optimization of the recipe for the synthesis of CuInS₂/ZnS nanocrystals supported by mechanistic considerations

Highly Bright Yellow-Green-Emitting CuInS₂ Colloidal Quantum Dots with Core/Shell/Shell Architecture for White Light-Emitting Diodes