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For commercial viability, a range of restricted, heavy-metal-free quantum dots has been developed showing bright emissions in the visible and near-infrared region of the spectrum and have similar optical properties to those of CdSe quantum dots. [citation needed] Among these materials are InP/ZnS, CuInS/ZnS, Si, Ge, and C.
Silicon quantum dots are metal-free biologically compatible quantum dots with photoluminescence emission maxima that are tunable through the visible to near-infrared spectral regions. These quantum dots have unique properties arising from their indirect band gap , including long-lived luminescent excited-states and large Stokes shifts .
As a new class of fluorescent carbon nanomaterials, CQDs possess the attractive properties of high stability, good conductivity, low toxicity, environmental friendliness, simple synthetic routes as well as comparable optical properties to quantum dots. [6]
Graphene quantum dots (GQDs) are graphene nanoparticles with a size less than 100 nm. [1] Due to their exceptional properties such as low toxicity, stable photoluminescence , chemical stability and pronounced quantum confinement effect, GQDs are considered as a novel material for biological, opto-electronics, energy and environmental applications.
Quantum dots (QDs) are nano-scale semiconductor particles on the order of 2–10 nm in diameter. They possess electrical properties between those of bulk semi-conductors and individual molecules, as well as optical characteristics that make them suitable for applications where fluorescence is desirable, such as medical imaging.
Larger quantum dots have closer electronic states than smaller quantum dots which means that the energy required to excite an electron from HOMO to the LUMO is lower than the same electronic transition in a smaller quantum dot. This quantum confinement effect can be observed as a red shift in absorbance spectra for nanocrystals with larger ...
In an experiment using silicon quantum dots near the interface of the substrate and the quantum dots, the power conversion efficiency of the solar cell increased. Silicon quantum dots can also be used as optical labels and drug delivery detection systems, [25] in addition to being used detect formaldehyde in water. [26]
Brus is a foundational figure in the research and development of quantum dots. Quantum dots are tiny semiconducting crystals whose nanoscale size gives them unique optical and electronic properties. [5] Brus was independently the first to synthesize them in a solution in 1982.