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Investigations on Exotic Forms of Carbon: Nanotubes, Graphene, Fullerene, and Quantum Dots
Published in Vineet Kumar, Praveen Guleria, Nandita Dasgupta, Shivendu Ranjan, Functionalized Nanomaterials I, 2020
Mahe Talat, Kalpana Awasthi, Vikas Kumar Singh, O.N. Srivastava
Quantum dots are very small semiconductor particles, only a few nanometres in size (2–10 nm), so small that their optical and electronic properties differ from those of larger particles and glow into a particular color after being illuminated by light. The color of the glow depends on the size of the quantum dot. After being illuminated by UV light, some of the electrons free themselves from the atoms. This property allows them to move around the quantum dots creating a conductance band where electrons can freely move and conduct electricity. The energy difference between the conductance band and the valence band is responsible for the color of that light. There are various sources and methods for synthesizing CQDs. One such method is “cutting” or fragmenting the graphene sheets into particles smaller than the radius (typically below 15 nm) which will result in graphene quantum dots (GQD). GQDs show fascinating physical and chemical properties such as high stability and luminescence on excitation, which are assigned to pronounced quantum confinement and edge effects.
Future Computing Technology: Quantum Computing and its Growth
Published in Durgesh Kumar Mishra, Nilanjan Dey, Bharat Singh Deora, Amit Joshi, ICT for Competitive Strategies, 2020
Priyanka Soni, Bharat Singh Deora
Quantum Dots are semiconductor nanoparticles exhibiting electrical and optical properties alike from larger particles because of quantum mechanics. They are also called as “Artificial atom”. Initially, Daniel Loss and David P. Di Vincenzo proposed an idea of implementing Quantum Dots as qubits [47]. They implement a universal set of one and two-qubit gates using a spin state of coupled single-electron quantum dots. As time evolved, now a day’s Quantum Dots are promising platforms for spin- based quantum computing, owing to their electrically tractable spin-spin coupling [48–49]. A broad variety of devices have been tested [50–54] in the quest of the high quality factor, exhibiting large coherence time. In recent, many experiments have been implemented on Quantum Dot spin qubits to ensure their coherence and fidelity up to 99.9% overcharge noise [55]. As the fault tolerance is achieved, two qubits programmable quantum processor has been developed using Quantum Dot and various algorithms have been implemented on the processor [56].
Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Quantum dots are nanometer sized fragments (the dots) of semiconductor crystalline material, which emits PHOTONS. The wavelength is based on the quantum confinement size of the dot. They are brighter and more persistent than organic chemical INDICATORS. They can be embedded in MICROBEADS for high throughput analytical chemistry. One should not confuse these with microscopic fluorescent bar codes which are micrometer sized. An important strategy for nonisotopic labeling of single molecules is the use of highly luminescent semiconductor nanocrystals, or ‘quantum dots,’ that can be covalently linked to biological molecules. This class of detectors, which range in size from 1–5 nm, have been exploited for biological labeling by a number of laboratories. Quantum dots offer several advantages over organic dyes, including increased brightness, stability against photobleaching, a broad continuous excitation spectrum, and a narrow, tunable, symmetric emission spectrum. Because quantum dots are nontoxic; and can be made to dissolve in water, efforts are underway to explore their use in labeling single molecules in living cells.
A comprehensive review on photocatalytic degradation of organic pollutants and microbial inactivation using Ag/AgVO3 with metal ferrites based on magnetic nanocomposites
Published in Cogent Engineering, 2023
Nuralhuda Aladdin Jasim, Shahlaa Esmail Ebrahim, Saad H. Ammar
Many applications for quantum dots (QDs) with special features can be found in the fields of energy, environment, and medicine. Due to their abundant availability, durability, availability, accessibility, and environmental friendliness, green natural resources are suitable for the synthesis of a range of nanoarchitectures. This critical review highlights recent advances in the environmentally friendly and sustainable synthesis of carbon, graphene, and metal-based QDs in addition to their important environmental applications, such as the creation of photocatalyst hydrogen, the deterioration of detrimental contaminants/pollutants, and the slight decrease in CO2. It also underlines the principal difficulties and opportunities that remain (Z. H. Jabbar & Ebrahim, 2022; Jabbar, Ebrahim, et al., 2021), (SM, 2018).
Performance enhancement of photovoltaic module using a sun tracker with side reflectors (STSR system)
Published in International Journal of Green Energy, 2023
Amirhosein Ekbatani, Behnam Mostajeran Goortani, Moein Karbalaei
An effective way to reduce the cost of electricity generated by a photovoltaic system is to use fewer photovoltaic cells for a given electricity demand. For this purpose, there are various solutions that are generally divided into two categories: (A) Increasing the efficiency of photovoltaic cells: Most part of the solar energy that reaches the cell surface in the infrared and ultraviolet region is not converted into electrical energy and wasted. There are various solutions to increase the absorption of photons by the solar cell in the infrared region and reduce the waste energy in the ultraviolet region, including the use of quantum dots (Munteanu and Autran 2011). Another way to increase the efficiency of photovoltaic cells is to lower their temperature; these include: heat transfer and reducing the temperature of solar cells using Nano fluids (Ahmed et al. 2019), the use of water flow on the module (Tabaei and Ameri 2015), and air flow behind the module (Kabeel and Abdelgaied 2019) or the simultaneous use of both techniques for cooling (Kabeel and Abdelgaied 2019).
Environmentally benign nanocrystals: challenges and future directions
Published in Journal of Information Display, 2019
Donghyo Hahm, Donghyun Ko, Byeong Guk Jeong, Sohee Jeong, Jaehoon Lim, Wan Ki Bae, Changhee Lee, Kookheon Char
The strict regulation of the use of toxic elements in real-life applications has motivated the research on a new class of quantum dots (QDs) made of heavy-metal-free compounds. Among the potential candidates, group III–V (InP, InAs, and InSb), group II–VI (ZnS, ZnSe, ZnTe, and ZnSexTe1−x), and group I–III–VI2 or I–V–VI2 (CuInS2, CuInSe2, AgInS2, AgInSe2, AgBiS2, and AgSbS2) semiconductors have been rigorously scrutinized as alternatives for Cd- or Pb-containing QDs. The advances in the synthesis and surface chemistry allow for the bandgap tunability covering the entire visible and NIR region, promising the practicable use of such QDs in a range of light-emitting or light-harvesting applications.