Silicon Quantum Dots - SiQD
Silicon (Si) is abundant in nature and is the mainstay of the semiconductor industry. It is considered non-toxic and biologically benign. Under a certain size, silicon nanomaterials exhibit interesting optoelectronic properties owing to the quantum confinement of charge carriers and these nanomaterials become known as silicon quantum dots (SiQDs).
The non-toxic nature of SiQDs makes them an enticing alternative to existing semiconducting quantum dots in the marketplace (e.g., cadmium, lead and indium-based materials), which either contain toxic or scarce metals.
Using proprietary preparative and functionalization methods, AQM produces high purity SiQDs (from 2 nm to 9 nm) with different surface modifications. With the variation of size and surface functionalities, these quantum dots can be made to emit light (under photoexcitation) across the visible and near-infrared spectra with high quantum yield. By using different surface functional groups, these quantum dots can be dispersed in a variety of organic solvents for thin-film device fabrication (e.g., displays and sensors) and in water for biological imaging and drug delivery.
Quantum dots represent the next wave of the semiconductor revolution. Their vast utility is, in part because of their tailorable size-dependent optical and chemical response. Because the material science can be manipulated, a variety of devices can be made. QDs have great potential as light-emitting materials for next-generation displays with highly saturated colors because of their sharp spectral resolution, high quantum efficiency and wavelength stability. Because QDs also convert light to current, they can be used as next-generation devices and systems including solar cells, photodetectors and sensors.
Once the SiQDs have been prepared and incorporated into different polymers, our dots are highly stable (brightness and quantum yield) under challenging environments such as high temperatures and moisture exposure. SiQDs are poised to revolutionize markets ranging from energy conversion and storage to medical diagnostics and treatment.
Using “solution” processing techniques, liquids, solids, powders and films of the material can be prepared. This allows for conveying the novel tunability of SiQDs absorption/emission spectra into a wide variety of everyday products.
AQM is introducing a new kind of quantum dot - very bright, (80% QY) silicon quantum dots (SiQDs) free from toxic heavy metals or other carcinogenic materials.
Silicon Advantages over Traditional QDs
Nanocrystalline silicon has great potential value because it is based on the same material that is the foundation of the electronics industry. Most QDs on the market today contain toxic metals (e.g., cadmium, lead, or indium) that severely limit their market reach. SiQDs are metal-free QDs that possess all of the favorable properties of their toxic metal-containing counterparts with the added benefits of elemental abundance, biologically compatibility, and optical properties that are tunable throughout the visible and near-IR spectral regions as well as in the temporal regime.
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They do not contain any heavy metals (e.g. Cd, In, Pb).
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Silicon is abundant and its chemical/electronic behavior is well-understood.
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Are non-toxic and biocompatible with human tissue.
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Bright photoluminescence (up to 85% quantum yield) and tunable from the visible to the near-IR.
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Low self-absorption due to a large Stokes shift of >400 meV.
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Stable photoluminescence in various composite materials at elevated temperatures of over 100 ᵒC and high humidity.
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The size tunability of colloidal SiQDs make them an attractive alternative to fluorescent dyes or doped phosphors since many colors can be achieved from the same material. Compared with dyes, SiQDs are exceedingly more stable.
Simply put: SiQDs are changing how we use light and color.
AQM Silicon Quantum Dots
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Hydrophobic, low κ solvents
(e.g., Toluene, Hexane)
PL from ca. 600 nm up to 1000 nm
PLQY: Type I: 10-40%
Type II: 30-60%
Type III: Up to 80%
Long PL lifetime (>50 μs)
3
max
Majority of organic solvents with medium κ
(e.g., Toluene, Ethanol, MIBK)
Mainly in alcohols and high κ organic solvents
(e.g., Ethanol, Methanol)
PL from ca. 600 nm up to 1000 nm
PLQY: typically, 30-65%
Long PL lifetime (>50 μs)
PL from ca. 650 nm up to 800 nm
PLQY: up to 30%
Long PL lifetime (>50 μs)
max
max
Most solvents to various degrees
(e.g., Water, Toluene, Ethanol)
PL from ca. 650 nm up to 800 nm
PLQY: 10-25%
Long PL lifetime (>50 μs)
max
Can be tuned to be dispersible in water (Mannose Termination) and/or hydrophobic solvents (amine groups)
PL ca. 410 - 500 nm
Short PL lifetime (on the order of ns)
max
Mainly in alcohols and organic solvents
(e.g., Ethanol, Methanol, Toluene)
PL from ca. 800 nm up to 950 nm
PLQY: 10-40%
Long PL lifetime (>50 μs)
max
Alkyl-Functionalized SiQDs
Ester-Terminated SiQDs
Acid-Terminated SiQDs
Mixed Surface SiQDs
N-Functionalized SiQDs
(Blue Emitting)
NIR SiQDs
Feature Properties
Surface Group
Compatible media (κ: dielectric constant)
Representative examples
Optical Properties
Photoluminescence (PL)
PL Quantum Yield (PLQY)
Product Sheet
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Please note, this table represents a limited number of our products. Contact us for more information and/or scientific consultation on specific requirements.
Optical data presented here may vary between samples depending on surface functionalization, synthetic methods, size of QDs, etc.
Types I to III come from different surface functionalization techniques. While Type I has lower PLQY, it surpasses other types in terms of stability and
scalability of the product.
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2
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