High color rendering index white light emitting diodes fabricated from a combination of carbon dots and zinc copper indium sulfide quantum dots
TL;DR: In this article, the authors combined blue emissive carbon dots with green and red emissives zinc copper indium sulfide (ZCIS) core/shell quantum dots (QDs) to achieve white light-emitting diodes (WLEDs) with a high color rendering index.
Abstract: In a line with most recent trends in developing non-toxic fluorescent nanomaterials, we combined blue emissive carbon dots with green and red emissive zinc copper indium sulfide (ZCIS) core/shell quantum dots (QDs) to achieve white light-emitting diodes (WLEDs) with a high color rendering index of 93. This indicates that ZCIS QDs, with their broad emission bands, can be employed to effectively make up the emission of carbon dots in the yellow and red regions to produce WLEDs in the wide region of color temperature by tuning the volume ratio of these constituting luminophores. Their electroluminescence characteristics including color rendering index, Commission Internationale de l'Eclairage (CIE) color coordinates, and color temperatures were evaluated as a function of forward current. The CIE-1931 chromaticity coordinates of the as-prepared WLEDs, exhibiting good stability, were slightly shifted from (0.321, 0.312) at 10 mA to (0.351, 0.322) at 30 mA, which was mainly caused by the different thermal quenching coefficients of carbon dots and ZCIS QDs.
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ETH Zurich1, Delft University of Technology2, Istituto Italiano di Tecnologia3, Ghent University4, University of Chicago5, Argonne National Laboratory6, University of Pennsylvania7, Los Alamos National Laboratory8, City University of Hong Kong9, University of Grenoble10, University of Marburg11, Seoul National University12, Johannes Kepler University of Linz13, University of Erlangen-Nuremberg14
TL;DR: The state of the art in research on colloidal NCs is reviewed focusing on the most recent works published in the last 2 years, where semiconductor NCs hold unique promise for near- and mid-infrared technologies, where very few semiconductor materials are available.
Abstract: Colloidal nanocrystals (NCs, i.e., crystalline nanoparticles) have become an important class of materials with great potential for applications ranging from medicine to electronic and optoelectronic devices. Today’s strong research focus on NCs has been prompted by the tremendous progress in their synthesis. Impressively narrow size distributions of just a few percent, rational shape-engineering, compositional modulation, electronic doping, and tailored surface chemistries are now feasible for a broad range of inorganic compounds. The performance of inorganic NC-based photovoltaic and light-emitting devices has become competitive to other state-of-the-art materials. Semiconductor NCs hold unique promise for near- and mid-infrared technologies, where very few semiconductor materials are available. On a purely fundamental side, new insights into NC growth, chemical transformations, and self-organization can be gained from rapidly progressing in situ characterization and direct imaging techniques. New phenom...
988 citations
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...By combining CDs that emit blue light and zinc copper indium sulfide QDs that emit in the green and red regions of the electromagnetic spectrum, white LEDs (Figure 13e) with a high color-rendering index of 93 have been realized.(400) These examples highlight the promise of CD-based composites with controlled chromaticity photo- and electroluminescence....
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TL;DR: Carbon dots represent an emerging class of fluorescent materials and provide a broad application potential in various fields of biomedicine and optoelectronics as discussed by the authors, and the applicability of carbon dots as components of light emitting diodes, which include carbon dot based electroluminescence, optical downconversion, and hybrid plasmonic devices.
745 citations
TL;DR: A white light-emitting diode (0.33, 0.33) is fabricated using perovskite quantum dot/silica composites and is shown to have greatly improved stability.
Abstract: A white light-emitting diode (0.33, 0.33) is fabricated using perovskite quantum dot/silica composites. It is shown to have greatly improved stability.
733 citations
TL;DR: In this paper, the authors reviewed the latest researches on the synthesis, structure, optical and electronic properties of CDs as well as their advanced applications in biomedicine and optoelectronics.
515 citations
TL;DR: Self-quenching in the aggregation state is overcome, and tunable solid-state photoluminescence of carbon-dot powder is achieved, and a novel concept, i.e., constructing dual-fluorescence morphologies from single luminescent species, is presented to realize white-light emission.
Abstract: Self-quenching in the aggregation state is overcome, and tunable solid-state photoluminescence of carbon-dot powder is achieved. Furthermore, based on the controllable optical property in organic solvents, a novel concept, i.e., constructing dual-fluorescence morphologies from single luminescent species, is presented to realize white-light emission.
493 citations
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TL;DR: It is reported that nanoscale carbon particles (carbon dots) upon simple surface passivation are strongly photoluminescent in both solution and the solid state.
Abstract: We report that nanoscale carbon particles (carbon dots) upon simple surface passivation are strongly photoluminescent in both solution and the solid state. The luminescence emission of the carbon dots is stable against photobleaching, and there is no blinking effect. These strongly emissive carbon dots may find applications similar to or beyond those of their widely pursued silicon counterparts.
3,817 citations
TL;DR: In this article, a review of the photo and electron properties of carbon nanodots is presented to provide further insight into their controversial emission origin and to stimulate further research into their potential applications, especially in photocatalysis, energy conversion, optoelectronics, and sensing.
Abstract: Carbon nanodots (C-dots) have generated enormous excitement because of their superiority in water solubility, chemical inertness, low toxicity, ease of functionalization and resistance to photobleaching. In this review, by introducing the synthesis and photo- and electron-properties of C-dots, we hope to provide further insight into their controversial emission origin (particularly the upconverted photoluminescence) and to stimulate further research into their potential applications, especially in photocatalysis, energy conversion, optoelectronics, and sensing.
2,262 citations
TL;DR: A new type and high density of surface state of GQDs arises, leading to high yields (more than 70 %) and excitation-independent emission and FLQY = fluorescence quantum yield.
Abstract: Helpful elements: A facile bottom-up method using citric acid and L-cysteine as a precursor has been developed to prepare graphene quantum dots (GQDs) co-doped with nitrogen and sulfur. A new type and high density of surface state of GQDs arises, leading to high yields (more than 70 %) and excitation-independent emission. FLQY = fluorescence quantum yield.
1,887 citations
TL;DR: It is shown that noncoordinating solvents not only are compatible with the synthesis of semiconductor nanocrystals, but also provide tunable reactivity of the monomers by simply varying the concentration of ligands in the solution.
Abstract: Semiconductor nanocrystals are of great interest for both fundamental research and industrial development.[1, 2] The lack of adequate synthetic methods for nanocrystals of the desired quality is currently a bottleneck in this field.[3] The relatively successful approaches, including the organometallic approach[4±8] and its alternatives,[9±13] are exclusively performed in coordinating solvents. Evidently, only a few compounds can act as the coordinating solvents,[11] and this makes it extremely challenging to identify a suitable reaction system for growing high-quality nanocrystals in most cases. Here we show that noncoordinating solvents not only are compatible with the synthesis of semiconductor nanocrystals, but also provide tunable reactivity of the monomers by simply varying the concentration of ligands in the solution. The tunable reactivity of the monomers provides a necessary balance between nucleation and growth, which is the key for control over the size and size distribution of the resulting nanocrystals.[5] In practice, such tunability has great potential to promote the synthesis of various semiconductor nanocrystals to the level of that of the well-developed CdSe N N
1,231 citations
TL;DR: In this paper, the authors synthesize monodispersed water-soluble fluorescent carbon nanoparticles (CNPs) from glucose by a one-step alkali or acid assisted ultrasonic treatment.
764 citations