Zeitschriftenartikel: „Quantum Dots (QD)“

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Prevenslik, Thomas. „Quantum Dots by QED“. Advanced Materials Research 31 (November 2007): 1–3. http://dx.doi.org/10.4028/www.scientific.net/amr.31.1.

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High quantum dot (QD) efficiency may be explained by excitons generated in the quantum electrodynamics (QED) confinement of electromagnetic (EM) radiation during the absorption of the laser radiation. There is general agreement that by the Mie theory laser photons are fully absorbed by QDs smaller than the laser wavelength. But how the absorbed laser photons are conserved by a QD is another matter. Classically, absorbed laser radiation is treated as heat that in a body having specific heat is conserved by an increase in temperature. However, the specific heats of QDs vanish at frequencies in the near infrared (NIR) and higher, and therefore an increase in temperature cannot conserve the absorbed laser photons. Instead by QED, the laser photon energy is first suppressed because the photon frequency is lower than the EM confinement frequency imposed by the QD geometry. To conserve the loss of suppressed EM energy, an equivalent gain must occur. But the only EM energy allowed in a QED confinement has a frequency equal to or greater than its EM resonance, and therefore the laser photons are then up-converted to the QD confinement frequency - the process called cavity QED induced EM radiation. High QD efficiency is the consequence of multiple excitons generated in proportion to very high QED induced Planck energy because at the nanoscale the EM confinement frequencies range from the vacuum ultraviolet (VUV) to soft x-rays (SXRs). Extensions of QED induced EM radiation are made to surface enhanced Raman spectroscopy (SERS) and light emission from porous silicon (PS).

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Han, Chang-Yeol, Hyun-Sik Kim und Heesun Yang. „Quantum Dots and Applications“. Materials 13, Nr. 4 (18.02.2020): 897. http://dx.doi.org/10.3390/ma13040897.

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It is the unique size-dependent band gap of quantum dots (QDs) that makes them so special in various applications. They have attracted great interest, especially in optoelectronic fields such as light emitting diodes and photovoltaic cells, because their photoluminescent characteristics can be significantly improved via optimization of the processes by which they are synthesized. Control of their core/shell heterostructures is especially important and advantageous. However, a few challenges remain to be overcome before QD-based devices can completely replace current optoelectronic technology. This Special Issue provides detailed guides for synthesis of high-quality QDs and their applications. In terms of fabricating devices, tailoring optical properties of QDs and engineering defects in QD-related interfaces for higher performance remain important issues to be addressed.

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Lobnik, Aleksandra, Špela Korent Urek und Matejka Turel. „Quantum Dots Based Optical Sensors“. Defect and Diffusion Forum 326-328 (April 2012): 682–89. http://dx.doi.org/10.4028/www.scientific.net/ddf.326-328.682.

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Luminescent sensors are chemical systems that can deliver information on the presence of selected analytes through the variations in their luminescence emission. With the advent of luminescent nanoparticles several new applications in the field of chemical sensing were explored. Among them, quantum dots (QD) represent inorganic semiconductor nanocrystals that are advantageous over conventional organic dyes from many different points of view. In this short review, the optical detection of various analytes using QD-based probes/sensors is presented and significant sensors characteristics are discussed. The biosensing approaches are not included in this article.

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Ghazi, Haddou EL. „Analysis of Quantum Dot Uses for Drug Delivery: Opportunities and Challenges“. Nanomedicine & Nanotechnology Open Access 9, Nr. 2 (2024): 1–3. http://dx.doi.org/10.23880/nnoa-16000302.

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A brief description of quantum dots (QD), which are remarkable Nanomaterials with substantial consequences for cutting-edge technology and science, is provided through this paper. The notion of quantum dots is used for their peculiar characteristics and operation, which originate from quantum phenomena inside these remarkable spherical crystals. Moreover, this paper also showcases some of the most widely used QD-based applications in biology, such as QD-based laser and drug delivery, highlighting their adaptability and potential impacts in several domains.

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Ledentsov, Nikolai N., Victor M. Ustinov, Dieter Bimberg, James A. Lott und Zh I. Alferov. „APPLICATIONS OF QUANTUM DOTS IN SEMICONDUCTOR LASERS“. International Journal of High Speed Electronics and Systems 12, Nr. 01 (März 2002): 177–205. http://dx.doi.org/10.1142/s0129156402001150.

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Quantum Dots (QD) provide unique opportunities to extend all the basic properties of heterostructure lasers and move further their applications. Practical fabrication of QD lasers became possible when techniques for self-organized growth allowed fabrication of dense and uniform arrays of narrow-gap nanodomains, coherently inserted in a semiconductor crystal matrix. Using of InAs QD lasers enabled significant improvement of device performance and extension of the spectral range on GaAs substrates to mainstream telecom wavelengths. Continuous wave 1.3 μm room-temperature output power of ~300 mW single mode for edge-emitters and of 1.2 mW multimode for vertical-cavity surface-emitting lasers are realized. Long operation lifetimes are manifested. The breakthrough become possible both due to development of self-organized growth and defect-reduction techniques in QD technology.

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Gajjela, Raja S. R., und Paul M. Koenraad. „Atomic-Scale Characterization of Droplet Epitaxy Quantum Dots“. Nanomaterials 11, Nr. 1 (03.01.2021): 85. http://dx.doi.org/10.3390/nano11010085.

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The fundamental understanding of quantum dot (QD) growth mechanism is essential to improve QD based optoelectronic devices. The size, shape, composition, and density of the QDs strongly influence the optoelectronic properties of the QDs. In this article, we present a detailed review on atomic-scale characterization of droplet epitaxy quantum dots by cross-sectional scanning tunneling microscopy (X-STM) and atom probe tomography (APT). We will discuss both strain-free GaAs/AlGaAs QDs and strained InAs/InP QDs grown by droplet epitaxy. The effects of various growth conditions on morphology and composition are presented. The efficiency of methods such as flushing technique is shown by comparing with conventional droplet epitaxy QDs to further gain control over QD height. A detailed characterization of etch pits in both QD systems is provided by X-STM and APT. This review presents an overview of detailed structural and compositional analysis that have assisted in improving the fabrication of QD based optoelectronic devices grown by droplet epitaxy.

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Lee, Changmin, Eunhee Nam, Woosuk Lee und Heeyeop Chae. „Hydrosilylation of Reactive Quantum Dots and Siloxanes for Stable Quantum Dot Films“. Polymers 11, Nr. 5 (18.05.2019): 905. http://dx.doi.org/10.3390/polym11050905.

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The reactive acrylate-terminated CdZnSeS/ZnS quantum dots (QDs) were designed and prepared by the effective synthetic route to bond with a siloxane matrix via hydrosilylation. The conventional QD with oleic acid ligands does not have any reactivity, so the QDs were functionalized to assign reactivity for the QDs by the ligand modification of two step reactions. The oleic acid of the QDs was exchanged for hydroxyl-terminated ligands as an intermediate product by one-pot reaction. The hydroxyl-terminated QDs and acrylate-containing isocyanates were combined by nucleophilic addition reaction with forming urethane bonds and terminal acrylate groups. No degradation in quantum yield was observed after ligand exchange, nor following the nucleophilic addition reaction. The modification reactions of ligands were quantitatively controlled and their molecular structures were precisely confirmed by FT-IR and 1H-NMR. The QDs with acrylate ligands were then reacted with hydride-terminated polydimethylsiloxane (H-PDMS) to form a QD-siloxane matrix by thermal curing via hydro-silylation for the first time. The covalent bonding between the QDs and the siloxane matrix led to improvements in the stability against oxygen and moisture. Stability at 85 °C and 85% relative humidity (RH) were both improved by 22% for the QD-connected siloxane QD films compared with the corresponding values for conventional QD-embedded poly(methylmethacrylate) (PMMA) films. The photo-stability of the QD film after 26 h under a blue light-emitting diode (LED) was also improved by 45% in comparison with those of conventional QD-embedded PMMA films.

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Zhang, Liyao, Yuxin Song, Qimiao Chen, Zhongyunshen Zhu und Shumin Wang. „InPBi Quantum Dots for Super-Luminescence Diodes“. Nanomaterials 8, Nr. 9 (10.09.2018): 705. http://dx.doi.org/10.3390/nano8090705.

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InPBi thin film has shown ultra-broad room temperature photoluminescence, which is promising for applications in super-luminescent diodes (SLDs) but met problems with low light emission efficiency. In this paper, InPBi quantum dot (QD) is proposed to serve as the active material for future InPBi SLDs. The quantum confinement for carriers and reduced spatial size of QD structure can improve light emission efficiently. We employ finite element method to simulate strain distribution inside QDs and use the result as input for calculating electronic properties. We systematically investigate different transitions involving carriers on the band edges and the deep levels as a function of Bi composition and InPBi QD geometry embedded in InAlAs lattice matched to InP. A flat QD shape with a moderate Bi content of a few percent over 3.2% would provide the optimal performance of SLDs with a bright and wide spectrum at a short center wavelength, promising for future optical coherence tomography applications.

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Jacak, L., J. Krasnyj, D. Jacak, R. Gonczarek, M. Krzyżosiak und P. Machnikowski. „Spin-Based Quantum Information Processing in Magnetic Quantum Dots“. Open Systems & Information Dynamics 12, Nr. 02 (Juni 2005): 133–41. http://dx.doi.org/10.1007/s11080-005-5724-0.

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We define the qubit as a pair of singlet and triplet states of two electrons in a He-type quantum dot (QD) placed in a diluted magnetic semiconductor (DMS) medium. The molecular field is here essential as it removes the degeneracy of the triplet state and strongly enhances the Zeeman splitting. Methods of qubit rotation as well as two-qubit operations are suggested. The system of a QD in a DMS is described in a way which allows an analysis of the decoherence due to spin waves in the DMS subsystem.

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Silva Filho, José Maria C. da, Victor A. Ermakov, Luiz G. Bonato, Ana F. Nogueira und Francisco C. Marques. „Self-Organized Lead(II) Sulfide Quantum Dots Superlattice“. MRS Advances 2, Nr. 15 (2017): 841–46. http://dx.doi.org/10.1557/adv.2017.246.

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ABSTRACTWe show that superlattice (SL) of PbS quantum dots (QD) can be easily prepared by drop casting of colloidal QD solution onto glass substrate and the ordering level can be controlled by the substrate temperature. A QD solution was dropped on glass and dried at 25, 40, 70 and 100°C resulting in formation of different SL structures. X-ray diffractograms (XRD) of deposited films show a set of sharp and intense peaks that are higher order satellites of a unique peak at 1.8 degrees (two theta), which corresponds, using the Bragg’s Law, to an interplanar spacing of 5.3 nm. The mean particles diameter, calculated through the broadening of the (111) peak of PbS using the Scherrer’s formula, were in agreement with the interplanar spacing. Transmission electron microscopy (TEM) measurements were also used to study the SL structure, which showed mainly a face centered cubic (FCC) arrangement of the QD. The photoluminescence (PL) spectrum of QD in the SL showed a shift toward lower energy compared to one in solution. It can be attributed to the fluorescence resonant energy transfer (FRET) between neighbors QD´s. Moreover, we observed greater redshift of PL peak for film with lower drying temperature, suggesting that it has a more organized structure.

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Litvin, A. P., I. V. Martynenko, F. Purcell-Milton, A. V. Baranov, A. V. Fedorov und Y. K. Gun'ko. „Colloidal quantum dots for optoelectronics“. Journal of Materials Chemistry A 5, Nr. 26 (2017): 13252–75. http://dx.doi.org/10.1039/c7ta02076g.

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Zenkevich, Eduard I., Thomas Blaudeck, Alexander Milekhin und Christian von Borczyskowski. „Size-Dependent Non-FRET Photoluminescence Quenching in Nanocomposites Based on Semiconductor Quantum Dots CdSe/ZnS and Functionalized Porphyrin Ligands“. International Journal of Spectroscopy 2012 (09.10.2012): 1–14. http://dx.doi.org/10.1155/2012/971791.

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We review recent experimental work to utilize the size dependence of the luminescence quenching of colloidal semiconductor quantum dots induced by functionalized porphyrin molecules attached to the surface to describe a photoluminescence (PL) quenching process which is different from usual models of charge transfer (CT) or Foerster resonant energy transfer (FRET). Steady-state and picosecond time-resolved measurements were carried out for nanocomposites based on colloidal CdSe/ZnS and CdSe quantum dots (QDs) of various sizes and surfacely attached tetra-mesopyridyl-substituted porphyrin molecules (“Quantum Dot-Porphyrin” nanocomposites), in toluene at 295 K. It was found that the major part of the observed strong quenching of QD PL in “QD-Porphyrin” nanocomposites can neither be assigned to FRET nor to photoinduced charge transfer between the QD and the chromophore. This PL quenching depends on QD size and shell and is stronger for smaller quantum dots: QD PL quenching rate constants scale inversely with the QD diameter. Based on the comparison of experimental data and quantum mechanical calculations, it has been concluded that QD PL quenching in “QD-Porphyrin” nanocomposites can be understood in terms of a tunneling of the electron (of the excited electron-hole pair) followed by a (self-) localization of the electron or formation of trap states. The major contribution to PL quenching is found to be proportional to the calculated quantum-confined exciton wave function at the QD surface. Our findings highlight that single functionalized molecules can be considered as one of the probes for the complex interface physics and dynamics of colloidal semiconductor QD.

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GUNAWAN, O., H. S. DJIE und B. S. OOI. „THREE-DIMENSIONAL MODEL FOR INTERDIFFUSED QUANTUM DOTS“. International Journal of Nanoscience 04, Nr. 04 (August 2005): 683–88. http://dx.doi.org/10.1142/s0219581x05003693.

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We report the study of the interdiffusion effect of quantum-dot (QD) heterostructures, focusing on the theoretical calculation of the electronic structure of interdiffused QDs. A computational model has been developed for QD superlattice system using Hamiltonian in reciprocal space domain to analyze the interdiffusion effect on electronic structure. The interdiffusion effects of QDs with various geometries having the same volume and the same lattice constant have been studied. In general, the interdiffusion effect in QDs is significantly pronounced since it occurs in three dimensions. Comparing the interdiffusion effect for the various shapes of QDs, it was found that the spherical QD has the lowest ground state and produces the largest blue-shift during the interdiffusion or intermixing process.

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Lantratov, Vladimir M., Sergey A. Mintairov, Sergey A. Blokhin, Nikolay A. Kalyuzhnyy, Nikolay N. Ledentsov, Maxim V. Maximov, Alexey M. Nadtochiy, Alexey S. Pauysov, Alexey V. Sakharov und Maxim Z. Shvarts. „AlGaAs/GaAs Photovoltaic Cells with InGaAs Quantum Dots“. Advances in Science and Technology 74 (Oktober 2010): 231–36. http://dx.doi.org/10.4028/www.scientific.net/ast.74.231.

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We studied the different carrier kinetic mechanisms involved into the interband absorption of quantum dots (QDs) by photocurrent spectroscopy. It was shown that in vertically coupled InGaAs QDs an effective carrier emission, collection and separation take place due to minizone formation. The possibility for the incorporation of vertically-coupled QDs into solar cells (SC) without any deterioration of structural quality of the p-i-n-junction has been shown. Due to the additional absorption of solar spectrum in QD media and the subsequent effective separation of photogenerated carriers, an increase (~1%) in short-circuit current density (Jsc) for the QD SC-devices has been demonstrated. However the insertion of QDs into intrinsic region reduced the open circuit voltage (Voc) of such devices. Moving the QD array in the base layer as well as including the Bragg reflector (BR) centered on 920 nm resulted in increase of the Voc. Moreover an improved absorption in the QD media for SC with BR led to further increase of Jsc (~1%). The efficiency for QD SCs at the level of 25% (30 suns AM1.5D) has been demonstrated.

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Barachevsky, V. A. „Photochromic quantum dots“. Izvestiya vysshikh uchebnykh zavedenii. Fizika, Nr. 11 (2021): 30–44. http://dx.doi.org/10.17223/00213411/64/11/30.

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The analysis of the results of fundamental and applied research in the field of creation of photochromic nanoparticles of the "core-shell" type, in which semiconductor nanocrystals - quantum dots were used as a core, and the shell included physically or chemically sorbed molecules of photochromic thermally relaxing (spiropyrans, spirooxazines , chromenes, azo compounds) or thermally irreversible (diarylethenes, fulgimides) compounds. It has been shown that such nanoparticles provide reversible modulation of the QD radiation intensity, which can be used in information and biomedical technologies.

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Żukowski, Krzysztof, Joanna Kosman und Bernard Juskowiak. „Light-Induced Oxidase Activity of DNAzyme-Modified Quantum Dots“. International Journal of Molecular Sciences 21, Nr. 21 (01.11.2020): 8190. http://dx.doi.org/10.3390/ijms21218190.

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Here, we report the synthesis of a quantum dot (QD)-DNA covalent conjugate to be used as an H2O2-free DNAzyme system with oxidase activity. Amino-coupling conjugation was carried out between amino-modified oligonucleotides (CatG4-NH2) and carboxylated quantum dots (CdTe@COOH QDs). The obtained products were characterized by spectroscopic methods (UV-Vis, fluorescence, circular dichroizm (CD), and IR) and the transmission electron microscopy (TEM) technique. A QD-DNA system with a low polydispersity and high stability in aqueous solutions was successfully obtained. The catalytic activity of the QD-DNA conjugate was examined with Amplex Red and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate)) indicators using reactive oxygen species (ROS) generated by visible light irradiation. The synthesized QD-DNAzyme exhibited enhanced catalytic activity compared with the reference system (a mixture of QDs and DNAzyme). This proved the assumption that the covalent attachment of DNAzyme to the surface of QD resulted in a beneficial effect on its catalytic activity. The results proved that the QD-DNAzyme system can be used for generation of the signal by light irradiation. The light-induced oxidase activity of the conjugate was demonstrated, proving that the QD-DNAzyme system can be useful for the development of new cellular bioassays, e.g., for the determination of oxygen radical scavengers.

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Janutka, A., L. Jacak, J. Krasnyj und P. Machnikowski. „Phonon Dephasing of the Exciton in InAs/GaAs Quantum Dots“. Open Systems & Information Dynamics 11, Nr. 04 (Dezember 2004): 391–400. http://dx.doi.org/10.1007/s11080-004-6630-6.

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The interaction of a exciton confined in a semiconductor quantum dot (QD) with bulk phonons (acoustical and optical) responsible for the exciton dephasing is studied. The decoherence of the exciton due to the creation of a polaron with long-living or decaying phonons is described. Characteristic dephasing times for an InAs / GaAs QD are estimated using Green function methods in order to determine fundamental time limitations for use of the QD exciton in quantum information processing.

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Shang, Yuequn, und Zhijun Ning. „Colloidal quantum-dots surface and device structure engineering for high-performance light-emitting diodes“. National Science Review 4, Nr. 2 (07.01.2017): 170–83. http://dx.doi.org/10.1093/nsr/nww097.

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Abstract The application of colloidal quantum dots for light-emitting devices has attracted considerable attention in recent years, due to their unique optical properties such as size-dependent emission wavelength, sharp emission peak and high luminescent quantum yield. Tremendous efforts have been made to explore quantum dots for light-emission applications such as light-emitting diodes (LEDs) and light converters. The performance of quantum-dots-based light-emitting diodes (QD-LEDs) has been increasing rapidly in recent decades as the development of quantum-dots synthesis, surface-ligand engineering and device-architecture optimization. Recently, the external quantum efficiencies of red quantum-dots LEDs have exceeded 20.5% with good stability and narrow emission peak. In this review, we summarize the recent advances in QD-LEDs, focusing on quantum-dot surface engineering and device-architecture optimization.

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IDOWU, MOPELOLA, und TEBELLO NYOKONG. „PHOTOPHYSICAL BEHAVIOR OF FLUORESCENT NANOCOMPOSITES OF PHTHALOCYANINE LINKED TO QUANTUM DOTS AND MAGNETIC NANOPARTICLES“. International Journal of Nanoscience 11, Nr. 02 (April 2012): 1250018. http://dx.doi.org/10.1142/s0219581x12500184.

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Fluorescent nanocomposite that consists of 3-aminopropyltriethoxysilane coated magnetic iron nanoparticles (MN), mercaptopropionic acid capped CdTe quantum dots (QD) and octacarboxy metallophthalocyanine (MOCPc) with either aluminium ((OH)AlOCPc) or zinc ( ZnOCPc ) as central metals have been prepared with (linked MOCPc-QD-MN) and without (mixed MOCPc-QD-MN) linking agents. The results presented give evidence of linkage within the components of the linked MOCPc-QD-MN. A red shift in the emission peak of QD within the linked nanocomposite compared to emission peak of QD alone was observed. Photoexcitation of both linked and mixed MOCPc-QD-MN at the excitation wavelength of the QD resulted in energy transfer from QD to the respective MOCPc while at the excitation wavelength of the MOCPc, a shift in emission peak of the linked MOCPc-QD-MN was observed resulting in large Stokes' shifts. The linked and mixed MOCPc-QD-MN were found to exhibit high triplet state quantum yields compared to the MOCPcs alone.

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Gber, Terkumbur E., Hitler Louis, Aniekan E. Owen, Benjamin E. Etinwa, Innocent Benjamin, Fredrick C. Asogwa, Muyiwa M. Orosun und Ededet A. Eno. „Heteroatoms (Si, B, N, and P) doped 2D monolayer MoS₂ for NH₃ gas detection“. RSC Advances 12, Nr. 40 (2022): 25992–6010. http://dx.doi.org/10.1039/d2ra04028j.

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2D transition metal dichalcogenide MoS2 monolayer quantum dots (MoS2-QD) and their doped boron (B@MoS2-QD), nitrogen (N@MoS2-QD), phosphorus (P@MoS2-QD), and silicon (Si@MoS2-QD) counterparts are proposed as selective sensors for NH3 gas.

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Ponomarev, V. O., und K. A. Tkachenko. „Prospects for the use of nanoparticles (quantum dots) in ophthalmology“. Fyodorov journal of ophthalmic surgery 142, Nr. 1 (18.03.2024): 86–93. http://dx.doi.org/10.25276/0235-4160-2024-1-86-93.

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Review Prospects for the use of nanoparticles (quantum dots) in ophthalmology V.O. Ponomarev, K.A. Tkachenko Eye Microsurger y Ekaterinburg Center, Ekaterinburg, Russian Federation Purpose. A systematic analysis of domestic and foreign literature devoted to the potential use of quantum dots (QD) in ophthalmology, as well as the identification of the main problems regarding the implementation of QD in ophthalmic practice. Material and methods. To carry out the review, a systematic analysis of scientific publications of domestic and foreign authors was carried out on the resources of PubMed, Medline, eLibrary from 2008 to 2021, devoted to the determination of physicochemical parameters, as well as the practical use of QD. Results. QD-based semiconductor nanoparticles are increasingly entrenched in modern science and medicine, in particular ophthalmology. This review defines the main physical parameters and physical and chemical properties of QD. Their potential applications are wide enough and focused on imaging, drug delivery, electrical stimulation and broad spectrum of anti-infective activity. Conclusion. To date, the existing limitations in the sphere of active QD application in ophthalmic practice are related to fundamental research in the field of acute and chronic cytotoxicity, selection of safe doses and concentrations of QD, working out mechanisms of their delivery, as well as in the study of mechanisms of chemical and biological interaction with the structures of the visual analyzer at dynamically changing physical parameters of QD (shape, size, features of functionalization and silanization). Interdisciplinary interactions between the pillars of fundamental medicine, physics, biology, chemistry, and ophthalmology, in particular, will probably allow us to realize in the nearest five years in clinical practice all the fundamental principles laid down in the previous studies. Key words: nanoparticles, quantum dots, anti-infective activity, imaging method, fluorescence

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Oszwałdowski, Sławomir, Katarzyna Zawistowska, Laura Grigsby und Kenneth Roberts. „Capillary electrophoretic separation and characterizations of CdSe quantum dots“. Open Chemistry 8, Nr. 4 (01.08.2010): 806–19. http://dx.doi.org/10.2478/s11532-010-0052-9.

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AbstractWe have developed a capillary electrophoresis method to characterize the QD surface ligand interactions with various surfactant systems. The method was demonstrated with 2–5 nm CdSe nanoparticles surface-passivated with trioctylphosphine oxide (TOPO). Water solubility was accomplished by surfactant-assisted phase transfer via an oil-in-water microemulsion using either cationic, anionic, or non-ionic surfactants. Interaction between the QD surface ligand (TOPO) and the alkyl chain of the surfactant molecule produces a complex and dynamic surface coating that can be characterized through manipulation of CE separation buffer composition and capillary surface modification. Additional characterization of the QD surface ligand interactions with surfactants was accomplished by UV-VIS spectroscopy, photoluminescence, and TEM. It is anticipated that studies such as these will elucidate the dynamics of QD surface ligand modifications for use in sensors.

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Семина, М. А., А. А. Головатенко, Т. В. Шубина und А. В. Родина. „Локализация носителей в квантовых точках с одноосной анизотропией формы и состава“. Физика твердого тела 61, Nr. 4 (2019): 636. http://dx.doi.org/10.21883/ftt.2019.04.47405.335.

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AbstractThe electronic and hole states in quantum dots (QD) of cubic II–VI semiconductors with a spheroidal shape and uniaxial anisotropy have been studied theoretically. The smooth potential energy profiles simulated by the Gauss function in all three spatial directions are considered. The energy level lowering and the energy splitting of the hole state from the valence band top Γ_8 by momentum 3/2 into the states with projections ±3/2, ±1/2 on the anisotropy axis are analyzed. The QD anisotropies of three types are considered: the QD size anisotropy, the QD potential barrier anisotropy, and the combined anisotropy. In the first case, flattened quantum dots, in which the characteristic size in the structure plane is larger than the size along the anisotropy axis, are considered. In the second case, QDs, in which the potential barrier height in the plane is lower than that along the anisotropy axis, are considered. In the third case, flattened quantum dots with the anisotropy of the size and the potential barrier are considered. The conditions of the charge carrier localization inside QD have been found, and the influence of the form and composition anisotropies on the energies of exciton transitions in the structures with Cd_ x Zn_1 – _ x Se quantum dots are discussed.

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Kitano, Keisuke, Seung Hyuk Lee, Sentaro Kida, Takahiro Doe, Yasushi Asaoka, Noboru Iwata, Makoto Izumi, Tetsu Tatsuma und Yasuhiko Arakawa. „83‐2: Inorganic ion treatment of Cd‐free quantum dots and applications to QD‐LED with improved characteristics“. SID Symposium Digest of Technical Papers 54, Nr. 1 (Juni 2023): 1166–69. http://dx.doi.org/10.1002/sdtp.16782.

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Inorganic ion treatment for Cd‐free colloidal quantum dot (QD) layers improved their carrier injection efficiency, resulting in improved external quantum efficiency (EQE) and electroluminescence (EL) lifetime of the QD light‐emitting diode (QD‐LED). Inorganic ion treated QD layers patterned at 176 ppi by photolithography enabled emission of each primary color.

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Жуков, Н. Д., М. В. Гавриков und С. Н. Штыков. „Размерное моделирование синтеза и проводимости коллоидных квантовых точек“. Физика и техника полупроводников 56, Nr. 6 (2022): 553. http://dx.doi.org/10.21883/ftp.2022.06.52588.9809.

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On the example of previously synthesized colloidal quantum dots (QD) of some semiconductors (CdSe, PbS, HgSe, InSb), the limiting sizes of nanocrystals with perfect structure during their synthesis were determined depending on the ratio of their volume and surface energies, which can vary from 6 nm for QD-InSb to 17 nm for QD-CdSe. The conductivity of single quantum dots in the interelectrode nanogap is one-electron, and their current-voltage characteristic has regions of electron tunneling through potential barriers, Coulomb current limitation, and resonant peaks of quantum conductivity. Dimensional relations are determined and nomograms of the relationship of dimensional parameters are constructed to ensure the conditions for quantum conductivity. The assumption about terahertz current oscillations is substantiated.

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WOLL, A. R., P. RUGHEIMER und M. G. LAGALLY. „SELF-ORGANIZED QUANTUM DOTS“. International Journal of High Speed Electronics and Systems 12, Nr. 01 (März 2002): 45–78. http://dx.doi.org/10.1142/s0129156402001125.

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We review the concepts and principal experimental results pertaining to the self-assembly and self-ordering of quantum dots in semiconductor systems. We focus on the kinetics and thermodynamics of the formation and evolution of coherently strained 3D islands, and the effects of strain on nucleation, growth, and island shape. We also discuss ongoing research on methods to control the density, size, and size distributions of strained islands, both within a single strained layer and in quantum dot (QD) multilayers.

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Gammon, Daniel. „High-Resolution Spectroscopy of Individual Quantum Dots in Wells“. MRS Bulletin 23, Nr. 2 (Februar 1998): 44–48. http://dx.doi.org/10.1557/s0883769400031262.

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Currently spectroscopists are studying many semiconductor quantum-dot (QD) systems in great detail because of their scientific and technological importance. However as in all nanostructure systems in which significant confinement energies exist, size fluctuations lead to inhomogeneous broadening of the spectral lines. This blurring of the spectra severely reduces the amount of information obtainable from spectroscopy. The finding has initiated an effort to isolate optically and study spectroscopically individual QDs. Studies involving individual QDs in most QD systems have been published. Here the results of a series of experiments are reviewed on GaAs QDs defined by interface fluctuations in narrow GaAs quantum wells. These experiments demonstrate the elegance and potential of single-QD spectroscopy.An example of single-QD photoluminescence (PL) spectroscopy appears in Figure 1. The spectra shown were obtained at a temperature of 6 K by successively reducing the size of the laser spot on a GaAs quantum-well sample through the use of small apertures in a metal mask. The bottom trace is a PL spectrum obtained with a macroscopic laser spot diameter of 25μm. The spectrum shows two broad peaks corresponding to the recombination of excitons in parts of the quantum well that are either 10 or 11 monolayers wide (2.8 or 3.1 nm). The spectrum is strongly inhomogeneously broadened as shown most directly by a reduction in the aperture size. The relatively broad lines break up into a decreasing number of extraordinarily narrow PL spikes as the aperture is reduced to submicroscopic dimensions. These PL spikes arise from excitons localized in individual QD potentials. Remarkably the linewidth decreases from several meV in the ensemble-averaged spectrum (25-μm aperture) to 10s of μeV in the single QD spectra, corresponding to an effective improvement in resolution of two orders in magnitude. By probing individual QDs, it becomes possible to resolve directly a number of phenomena that previously were hidden in the inhomogeneous linewidth.

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Reznik, Ivan, Andrey Zlatov, Mikhail Baranov, Roman Zakoldaev, Andrey Veniaminov, Stanislav Moshkalev und Anna Orlova. „Photophysical Properties of Multilayer Graphene–Quantum Dots Hybrid Structures“. Nanomaterials 10, Nr. 4 (09.04.2020): 714. http://dx.doi.org/10.3390/nano10040714.

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Photoelectrical and photoluminescent properties of multilayer graphene (MLG)–quantum dots (QD) hybrid structures have been studied. It has been shown that the average rate of transfer from QDs to the MLG can be estimated via photoinduced processes on the QDs’ surfaces. A monolayer of CdSe QDs can double the photoresponse amplitude of multilayer graphene, without influencing its characteristic photoresponse time. It has been found that efficient charge or energy transfer from QDs to MLG with a rate higher than 3 × 108 s−1 strongly inhibits photoinduced processes on the QD surfaces and provides photostability for QD-based structures.

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Li, Yuan-He, Zhi-Yao Zhuo, Jian Wang, Jun-Hui Huang, Shu-Lun Li, Hai-Qiao Ni, Zhi-Chuan Niu, Xiu-Ming Dou und Bao-Quan Sun. „Controlling exciton spontaneous emission of quantum dots by Au nanoparticles“. Acta Physica Sinica 71, Nr. 6 (2022): 067804. http://dx.doi.org/10.7498/aps.71.20211863.

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As an ideal single-photon source, quantum dots (QDs) can play a unique role in the field of quantum information. Controlling QD exciton spontaneous emission can be achieved by anti-phase coupling between QD exciton dipole field and Au dipole field after QD film has been transferred onto the Si substrate covered by Au nanoparticles. In experiment, the studied InAs/GaAs QDs are grown by molecular beam epitaxy (MBE) on a (001) semi-insulation substrate. The films containing QDs with different GaAs thickness values are separated from the GaAs substrate by etching away the AlAs sacrificial layer and transferring the QD film to the silicon wafer covered by Au nanoparticles with a diameter of 50 nm. The distance D (thickness of GaAs) from the surface of the Au nanoparticles to the QD layer is 10, 15, 19, 25, and 35 nm, separately. A 640-nm pulsed semiconductor laser with a 40-ps pulse length is used to excite the QD samples for measuring QD exciton photoluminescence and time-resolved photoluminescence spectra at 5 K. It is found that when the distance D is 15–35 nm the spontaneous emission rate of exciton is suppressed. And when D is close to 19 nm, the QD spontaneous emission rate decreases to <inline-formula><tex-math id="M2">\begin{document}$ ~{10}^{-3} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20211863_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20211863_M2.png"/></alternatives></inline-formula>, which is consistent with the theoretical calculations. The physical mechanism of long-lived exciton luminescence observed in experiment lies in the fact that Au nanoparticles scatter the light field of the exciton radiation in the QD wetting layer, and the phase of the scattered field is opposite to the phase of the exciton radiation field. Therefore, the destructive interference between the exciton radiation field and scattering field of Au nanoparticles results in long-lived exciton emission observed in experiment.

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Chandrashekar, Hediyala B., Arun Maji, Ganga Halder, Sucheta Banerjee, Sayan Bhattacharyya und Debabrata Maiti. „Photocatalyzed borylation using water-soluble quantum dots“. Chemical Communications 55, Nr. 44 (2019): 6201–4. http://dx.doi.org/10.1039/c9cc01737b.

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Das, Anirban, Eric Hall und Chien M. Wai. „Noncovalent Attachment of PbS Quantum Dots to Single- and Multiwalled Carbon Nanotubes“. Journal of Nanotechnology 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/285857.

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Attachment of PbS quantum dots (QD) to single-walled carbon nanotubes (SWNT) and multiwalled carbon nanotubes (MWCNT) is described; wherein commercially obtained PbS-QD of size 2.7 nm, stabilized by oleic acid, are added to a suspension of single- or multiwalled carbon nanotubes (CNT) prefunctionalized noncovalently with 1,2-benzenedimethanethiol (1,2-BDMT) in ethanol. The aromatic part of 1,2-BDMT attaches to the CNT byπ-πstacking interactions, noncovalently functionalizing the CNT. The thiol part of the 1,2-BDMT on the functionalized CNT replaces oleic acid on the surface of the QD facilitating the noncovalent attachment of the QD to the CNT. The composites were characterized by TEM and FTIR spectroscopy. Quenching of NIR fluorescence of the PbS-QD on attachment to the carbon nanotubes (CNT) was observed, indicating FRET from the QD to the CNT.

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Arvani, M., K. Virkki, F. Abou-Chahine, A. Efimov, A. Schramm, N. V. Tkachenko und D. Lupo. „Photoinduced hole transfer in QD–phthalocyanine hybrids“. Physical Chemistry Chemical Physics 18, Nr. 39 (2016): 27414–21. http://dx.doi.org/10.1039/c6cp04374g.

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Djotyan, A. P., A. A. Avetisyan und E. M. Kazaryan. „Interband Light Absorption in Semiconductor Quantum Dots Connected with the Charged and Neutral Exciton - Donor Complexes“. Key Engineering Materials 277-279 (Januar 2005): 893–98. http://dx.doi.org/10.4028/www.scientific.net/kem.277-279.893.

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The interband light absorption in spherical quantum dot (QD) of semiconductors connected with the charged and neutral exciton-donor complexes are studied theoretically. The oscillator strength for interband optical transition from valence band to the ground state of excitondonor complex in spherical QD has been investigate. The calculations were performed in the cases of infinite and finite potential barrier of QD. The dependences of the oscillator strength on the radius of the QD were obtained. It was shown that the quantum confinement gives rise a giant oscillator strength per impurity.

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Li, Shuang-ling, Jing Yang, Xiao-fei Lei, Jian-na Zhang, Hong-li Yang, Kun Li und Chang-qing Xu. „Peptide-Conjugated Quantum Dots Act as the Target Marker for Human Pancreatic Carcinoma Cells“. Cellular Physiology and Biochemistry 38, Nr. 3 (2016): 1121–28. http://dx.doi.org/10.1159/000443062.

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Background/Aims: In the present study, we describe a novel and straightforward approach to produce a cyclic- arginine-glycine-aspartic (RGD)-peptide-conjugated quantum dot (QD) probe as an ideal target tumor biomarker. Due to its specific structure, the probe can be used for targeted imaging of pancreatic carcinoma cells. Methods: Pancreatic carcinoma cells were routinely cultured and marked with QD-RGD probe. The QD-RGD probe on the fluorescence-labeled cancer cell was observed by fluorescence microscopy and laser confocal microscopy. Cancer cell viability was detected by MTT assay after culturing with QD-RGD probe. Results: Fluorescence microscopy and laser confocal microscopy displayed that 10nmol/L QD-RGD probe was able to effectively mark pancreatic carcinoma cells. In comparison with organic dyes and fluorescent proteins, the quantum dot-RGD probe had unique optical and electronic properties. Conclusion: QD-RGD probe has a low cytotoxicity with an excellent optical property and biocompatibility. These findings support further evaluation of QD-RGD probes for the early detection of pancreatic cancer.

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Yang, Xiaotun, Ning Huang und Yong Zhang. „Encapsulation of Luminescent Quantum Nanodots in Polystyrene Nanocapsules by Microemulsion Polymerization“. Journal of Metastable and Nanocrystalline Materials 23 (Januar 2005): 19–22. http://dx.doi.org/10.4028/www.scientific.net/jmnm.23.19.

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This paper reported on the one-step synthesis of polystyrene-quantum dots (PS@QD)nanoparticles using microemulsion polymerization method. The synthesized QD and PS@QD nanoparticles were characterized by UV, fluorescence spectroscopy, transmission electron microscopy (TEM) and fluorescence microscopy. The PS@QD is highly luminescent, which have the potential to be used as fluorescent probes in biological staining and diagnostics.

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Chen, Lung-Chien, Ching-Ho Tien, Zong-Liang Tseng und Jun-Hao Ruan. „Enhanced Efficiency of MAPbI3 Perovskite Solar Cells with FAPbX3 Perovskite Quantum Dots“. Nanomaterials 9, Nr. 1 (19.01.2019): 121. http://dx.doi.org/10.3390/nano9010121.

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We describe a method to enhance power conversion efficiency (PCE) of MAPbI3 perovskite solar cell by inserting a FAPbX3 perovskite quantum dots (QD-FAPbX3) layer. The MAPbI3 and QD-FAPbX3 layers were prepared using a simple, rapid spin-coating method in a nitrogen-filled glove box. The solar cell structure consists of ITO/PEDOT:PSS/MAPbI3/QD-FAPbX3/C60/Ag, where PEDOT:PSS, MAPbI3, QD-FAPbX3, and C60 were used as the hole transport layer, light-absorbing layer, absorption enhance layer, and electron transport layer, respectively. The MAPbI3/QD-FAPbX3 solar cells exhibit a PCE of 7.59%, an open circuit voltage (Voc) of 0.9 V, a short-circuit current density (Jsc) of 17.4 mA/cm2, and a fill factor (FF) of 48.6%, respectively.

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Ünal, Vildan Üstoğlu, Erem Birşey und Ertan Akşahin. „A comparison of optical properties of disc-like and spherical quantum dots“. Journal of Nonlinear Optical Physics & Materials 27, Nr. 03 (September 2018): 1850034. http://dx.doi.org/10.1142/s0218863518500340.

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The optical properties of quantum dots (QDs) are of interest to many researchers. In this study, the optical coeefficients analyzed include the optical absorption, the refractive index; both the linear and nonlinear cases together with the electric field effect. The electronic structures of the disc-like and spherical QDs are calculated by using the effective-mass approximation. The results show that the total change in the refractive index and the optical absorption increase with increasing QD size, the peaks are shifted with the changing QD size. The nonlinear optical properties increase with the external electric field and the optical intensity. Comparison of QD types shows that the peaks are red-shifted for the disc-like QD and lower than those in the spherical QD case.

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Lamri, Gwénaëlle, Artur Movsesyan, Edite Figueiras, Jana B. Nieder, Jean Aubard, Pierre-Michel Adam, Christophe Couteau, Nordin Felidj und Anne-Laure Baudrion. „Photochromic control of a plasmon–quantum dots coupled system“. Nanoscale 11, Nr. 1 (2019): 258–65. http://dx.doi.org/10.1039/c8nr08076c.

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KAWANO, YUKIO, TOMOKO FUSE und KOJI ISHIBASHI. „ULTRA-HIGHLY SENSITIVE TERAHERTZ DETECTION USING CARBON-NANOTUBE QUANTUM DOTS“. International Journal of High Speed Electronics and Systems 17, Nr. 03 (September 2007): 567–70. http://dx.doi.org/10.1142/s0129156407004758.

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We have observed that Terahertz (THz) irradiation to a carbon nanotube quantum dot (CNT-QD) leads to the generation of an excess current in the Coulomb blockade regime. It was found that this THz detected signal survives even when the incident THz wave is extremely weak (~1 fW). This means that the CNT-QD could works as a highly sensitive THz detector.

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Pokutnyi, S. I., und N. G. Shkoda. „Electron tunneling in the germanium/silicon heterostructure with germanium quantum dots: theory“. Himia, Fizika ta Tehnologia Poverhni 12, Nr. 4 (30.12.2021): 306–13. http://dx.doi.org/10.15407/hftp12.04.306.

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It is shown that electron tunneling through a potential barrier that separates two quantum dots of germanium leads to the splitting of electron states localized over spherical interfaces (a quantum dot – a silicon matrix). The dependence of the splitting values of the electron levels on the parameters of the nanosystem (the radius a quantum dot germanium, as well as the distance D between the surfaces of the quantum dots) is obtained. It has been shown that the splitting of electron levels in the QD chain of germanium causes the appearance of a zone of localized electron states, which is located in the bandgap of silicon matrix. It has been found that the motion of a charge-transport exciton along a chain of quantum dots of germanium causes an increase in photoconductivity in the nanosystem. It is shown that in the QD chain of germanium a zone of localized electron states arises, which is located in the bandgap of the silicon matrix. Such a zone of local electron states is caused by the splitting of electron levels in the QD chain of germanium. Moreover, the motion of an electron in the zone of localized electron states causes an increase in photoconductivity in the nanosystem. The effect of increasing photoconductivity can make a significant contribution in the process of converting the energy of the optical range in photosynthesizing nanosystems. It has been found that comparison of the splitting dependence of the exciton level Eех(а) at a certain radius a QD with the experimental value of the width of the zone of localized electron states arising in the QD chain of germanium, allows us to obtain the distances D between the QD surfaces. It has been shown that by changing the parameters of Ge/Si heterostructures with germanium QDs (radius of a germanium QD, as well as the distance D between the surfaces of the QDs), it is possible to vary the positions and widths of the zones of localized electronic states. The latter circumstance opens up new possibilities in the use of such nanoheterostructures as new structural materials for the creation of new nano-optoelectronics and nano-photosynthesizing devices of the infrared range.

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Strassner, Johannes, Johannes Richter, Thomas Loeber, Christoph Doering und Henning Fouckhardt. „Epitaxial Growth of Optoelectronically Active Ga(As)Sb Quantum Dots on Al-Rich AlGaAs with GaAs Capsule Layers“. Advances in Materials Science and Engineering 2021 (19.05.2021): 1–10. http://dx.doi.org/10.1155/2021/8862946.

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We present a study of optoelectronically active Ga(As)As quantum dots (QDs) on Al-rich AlxGa1-xAs layers with Al concentrations up to x = 90%. So far, however, it has not been possible to grow optoelectronically active Ga(As)As QDs epitaxially directly on and in between Al-rich barrier layers in the AlGaInAsSb material system. A QD morphology might appear on the growth front, but the QD-like entities will not luminesce. Here, we use photoluminescence (PL) measurements to show that thin Al-free capsule layers between Al-rich barrier layers and the QD layers can solve this problem; this way, the QDs become optoelectronically active; that is, the dots become QDs. We consider antimonide QDs, that is, Ga(As)Sb QDs, either on GaAs for comparison or on AlxGa1-xAs barriers (x >10%) with GaAs capsule layers in between. We also discuss the influence of QD coupling both due to stress/strain from neighboring QDs and quantum-mechanically on the wavelength of the photoluminescence peak. Due to their mere existence, the capsule layers alter the barriers by becoming part of them. Quantum dots applications such as QD semiconductor lasers for spectroscopy or QDs as binary storage cells will profit from this additional degree of design freedom.

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Patil, Anisha B., Pooja L. Chaudhary und Parag V. Adhyapak. „Carbon dots–cadmium sulfide quantum dots nanocomposite for ‘on–off’ fluorescence sensing of chromium(vi) ions“. RSC Advances 14, Nr. 18 (2024): 12923–34. http://dx.doi.org/10.1039/d4ra00436a.

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Ahn, Namyoung, Clément Livache, Valerio Pinchetti, Heeyoung Jung, Ho Jin, Donghyo Hahm, Young-Shin Park und Victor I. Klimov. „Electrically driven amplified spontaneous emission from colloidal quantum dots“. Nature 617, Nr. 7959 (03.05.2023): 79–85. http://dx.doi.org/10.1038/s41586-023-05855-6.

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AbstractColloidal quantum dots (QDs) are attractive materials for realizing solution-processable laser diodes that could benefit from size-controlled emission wavelengths, low optical-gain thresholds and ease of integration with photonic and electronic circuits1–7. However, the implementation of such devices has been hampered by fast Auger recombination of gain-active multicarrier states1,8, poor stability of QD films at high current densities9,10 and the difficulty to obtain net optical gain in a complex device stack wherein a thin electroluminescent QD layer is combined with optically lossy charge-conducting layers11–13. Here we resolve these challenges and achieve amplified spontaneous emission (ASE) from electrically pumped colloidal QDs. The developed devices use compact, continuously graded QDs with suppressed Auger recombination incorporated into a pulsed, high-current-density charge-injection structure supplemented by a low-loss photonic waveguide. These colloidal QD ASE diodes exhibit strong, broadband optical gain and demonstrate bright edge emission with instantaneous power of up to 170 μW.

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Mohamed, Walied A. A., Hala Abd El-Gawad, Saleh Mekkey, Hoda Galal, Hala Handal, Hanan Mousa und Ammar Labib. „Quantum dots synthetization and future prospect applications“. Nanotechnology Reviews 10, Nr. 1 (01.01.2021): 1926–40. http://dx.doi.org/10.1515/ntrev-2021-0118.

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Abstract Quantum dots (QDs) are nanocrystals of a semiconductor material that exist in a size regime less than 10 nm. QDs have become promising nanoparticles for a wide variety of different applications. However, the major drawback of QDs is their potential toxicity. This review reports on some recent methods for the synthesis of QDs and explores their properties, structures, applications, and toxicity. QDs are extraordinary because their minute size produces a physically confined electron cloud, an effect known as the quantum confinement. Certainly, because of their special properties as they had a great unique optical, electronic, and chemical properties that were not observe in other materials. These unique properties of the QD are an attractive material for a variety of scientific and commercial applications, most of them recently been realized, such as biosensors, bioimaging, photodetectors, displays, solar cells, wastewater treatment, and quantum computers. Finally, but not the end, an interesting potential QD application in future perspectives will expect as light-emitting diode products, biomedical applications, and Li-Fi.

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Yang, Hongcheng, Miao Zhou, Haodong Tang, Mingyu Sun, Pai Liu, Yizun Liu, Lixuan Chen et al. „Enhanced light emission of quantum dot films by scattering of poly(zinc methacrylate) coating CdZnSeS/ZnS quantum dots and high refractive index BaTiO3 nanoparticles“. RSC Advances 10, Nr. 53 (2020): 31705–10. http://dx.doi.org/10.1039/d0ra05389a.

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We report QD films based on a poly(zinc methacrylate) coating with alloyed green-emitting CdZnSeS/ZnS quantum dots (QDs@PZnMA) together with high refractive-index BaTiO₃ nanoparticles to enhance the scattering coefficient of the QD films.

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Wang, Xinyu, Wayesh Qarony, Ping Kwong Cheng, Mohammad Ismail und Yuen Hong Tsang. „Photoluminescence of PdS2 and PdSe2 quantum dots“. RSC Advances 9, Nr. 65 (2019): 38077–84. http://dx.doi.org/10.1039/c9ra07445g.

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PdS₂ and PdSe₂ QDs are fabricated via liquid exfoliation using NMP solvent. The PL behaviors of these QD solutions are studied. The obtained results suggest promising optoelectronic applications with group-10 TMD QDs in the future.

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Yu, Ying, Guo-Wei Zha, Xiang-Jun Shang, Shuang Yang, Ban-Quan Sun, Hai-Qiao Ni und Zhi-Chuan Niu. „Self-assembled semiconductor quantum dots decorating the facets of GaAs nanowire for single-photon emission“. National Science Review 4, Nr. 2 (01.03.2017): 196–209. http://dx.doi.org/10.1093/nsr/nwx042.

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Abstract In this chapter, we discuss the epitaxial growth of self-assembled quantum dots (QDs) in GaAs nanowires (NWs) and the characteristics of their single-photon emissions. We demonstrate Ga droplet-induced gold-free vapor-liquid-solid growth of hexagonal GaAs/AlGaAs core–shell NWs, branched GaAs NWs and tailored nanostructured morphologies on the NW facets. Particularly, we show two new types of QD-in-NW systems: one is a single InAs QD formed at the corner of a branched GaAs NW, and the other is a single GaAs QD formed on the NW facet. Sharp excitonic emission spectral lines are observed with vanishing two-photon emission probability. Furthermore, a single GaAs QD is achieved at the site of a single AlGaAs quantum ring (QR) on the NW facet. In addition, these NW-based single QDs are in-situ probed and integrated with single-mode optical fibers to achieve all-fiber-output single-photon sources for potential application in quantum integrated networks.

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Becker-Koch, David, Miguel Albaladejo-Siguan, Vincent Lami, Fabian Paulus, Hengyang Xiang, Zhuoying Chen und Yana Vaynzof. „Ligand dependent oxidation dictates the performance evolution of high efficiency PbS quantum dot solar cells“. Sustainable Energy & Fuels 4, Nr. 1 (2020): 108–15. http://dx.doi.org/10.1039/c9se00602h.

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The stability of lead sulfide (PbS) quantum dots (QD) under continuous illumination in oxygenated environments depends on the choice of ligands, determining the evolution of photovoltaic performance of high efficiency PbS QD solar cells.

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Skurlov, Ivan D., Iurii G. Korzhenevskii, Anastasiia S. Mudrak, Aliaksei Dubavik, Sergei A. Cherevkov, Petr S. Parfenov, Xiaoyu Zhang, Anatoly V. Fedorov, Aleksandr P. Litvin und Alexander V. Baranov. „Optical Properties, Morphology, and Stability of Iodide-Passivated Lead Sulfide Quantum Dots“. Materials 12, Nr. 19 (01.10.2019): 3219. http://dx.doi.org/10.3390/ma12193219.

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Iodide atomic surface passivation of lead chalcogenides has spawned a race in efficiency of quantum dot (QD)-based optoelectronic devices. Further development of QD applications requires a deeper understanding of the passivation mechanisms. In the first part of the current study, we compare optics and electrophysical properties of lead sulfide (PbS) QDs with iodine ligands, obtained from different iodine sources. Methylammonium iodide (MAI), lead iodide (PbI2), and tetrabutylammonium iodide (TBAI) were used as iodine precursors. Using ultraviolet photoelectron spectroscopy, we show that different iodide sources change the QD HOMO/LUMO levels, allowing their fine tuning. AFM measurements suggest that colloidally-passivated QDs result in formation of more uniform thin films in one-step deposition. The second part of this paper is devoted to the PbS QDs with colloidally-exchanged shells (i.e., made from MAI and PbI2). We especially focus on QD optical properties and their stability during storage in ambient conditions. Colloidal lead iodide treatment is found to reduce the QD film resistivity and improve photoluminescence quantum yield (PLQY). At the same time stability of such QDs is reduced. MAI-treated QDs are found to be more stable in the ambient conditions but tend to agglomerate, which leads to undesirable changes in their optics.

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En-nadir, Redouane. „Quantum Dots' Role in Cancer Diagnosis: An overview on NanoFluorescence in Oncology“. Nanomedicine & Nanotechnology Open Access 8, Nr. 4 (2023): 1–9. http://dx.doi.org/10.23880/nnoa-16000276.

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This paper highlights the significant advantages of utilizing quantum dots (QDs) in cancer detection. The discussion begins with an introduction to Quantum Dots and Their Properties, emphasizing their unique characteristics. Subsequently, the paper explores the utility of Quantum Dots as Imaging Probes, shedding light on their role in enhancing imaging capabilities for cancer diagnosis. The focus then shifts to their pivotal role in cancer targeting, particularly for early detection. Finally, Challenges and Future Prospects in the field of QD-based cancer detection are addressed. This comprehensive overview underscores the potential of quantum dots in revolutionizing cancer diagnosis and opens avenues for further research and development.

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