Type‐
            <scp>I</scp>
            and Type‐
            <scp>II</scp>
            Core–Shell Quantum Dots: Synthesis and Characterization

Dorfs, Dirk; Hickey, Stephen G.; Eychmüller, Alexander

doi:10.1002/9783527610419.ntls0199

Cited by 11 publications

(11 citation statements)

References 95 publications

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“…In type II core/shell systems, the electrons and holes are present in two different compartments, causing the rate of recombination of the charged carriers to be slow. The slow rate of recombination of the charge carriers is the reason for the increased luminescence lifetime exhibited by type II core/shell systems [35]. In Quasi type II core/shell systems, one carrier is localised in the core or shell while the other is delocalised as a whole particle.…”

Section: Ternary Qds Core/shell Systemmentioning

confidence: 99%

Synthesis strategies and application of ternary quantum dots — in cancer therapy

Aladesuyi

Oluwafemi

2020

Nano-Structures & Nano-Objects

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Semiconductor nanoparticles also known as quantum dots (QDs) have continued to receive more attention from researchers due to their unique optical, magnetic and photo physical properties which made them useful as biomedical materials, solar cells, catalyst etc. However, ternary I-III-VI QDs have shown to be a safer alternative to the binary II-VI or IV-VI QDs due to the absent of heavy toxic elements such as Cd and Pb. Cancer management and therapy in Africa has been bedevilled by a lot of challenges such as inaccurate diagnosis and ineffective therapeutic methods. Therefore, the need to develop an appropriate approach for cancer detection and treatment is of paramount importance. Tunable optical properties and absorption in the near infra-red region of the ternary QDs makes them useful as fluorescent probes in cancer detection and treatment. They have the ability to detect specific cancer cells including those that are not easily detected by modern imaging technique. Also, properties such as non-bleaching, stability, water solubility etc. made them a desirable fluorophore when compared to conventional dyes. Most cancer drugs suffer from inherent shortcomings such as limited absorption, insolubility and aggregation. However, these shortcomings can be overcome when these drugs are applied in form of conjugated systems. The use of QDs as conjugates has revolutionise the treatment of cancer in the 21st century. This review provides information about the synthesis strategies, optical properties, hydrophilization and bioconjugation of ternary I-III-VI QDs. Furthermore, we described the various biomedical applications in biosensors, bioimaging, drug delivery and phototherapeutic techniques. Finally, we looked at the challenges and future perspective of these QDs in cancer management.

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Section: Ternary Qds Core/shell Systemmentioning

confidence: 99%

Synthesis strategies and application of ternary quantum dots — in cancer therapy

Aladesuyi

Oluwafemi

2020

Nano-Structures & Nano-Objects

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“…Various type-I core-shell structures like the, CdSe/ZnS, CdSe/CdS, CdS/ZnS and InP/ZnS [13,[18][19][20] have been studied widely and were found to represent extremely stimulating options of representing the common organic dye molecules in applications such as labelling processes especially biolabelling where the in vitro or in vivo labelling of a bio molecule is conducted and it is detected using the PL of the QD [21]. In addition, various core-shell nanostructures including CdS/HgS/CdS ZnSe/ZnS CdSe/CdS/ZnS were extensively studied and reported by Dirks et al [22]. These studies presented various concepts and preparation techniques used.…”

Section: Introductionmentioning

confidence: 99%

Effects of growth time on the material properties of CdTe/CdSe core/shell nanoparticles prepared by a facile wet chemical route

Kiprotich

Dejene

Onani

2022

Mater. Res. Express

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This study presents a facile synthetic approach used to prepare CdTe/CdSe core/shell nanoparticles (NPs). The effects of reaction time on the material properties of the CdTe/CdSe NPs are reported. It was realized that the reaction time has significant impact on the CdSe shell growth on the CdTe core. Various techniques were used to characterize the as-prepared CdTe/CdSe NPs. The X-ray diffraction (XRD) was used to study the crystal structure and the possible growth of the CdSe shell on the CdTe core. The results obtained indicated the formation of zinc blende crystal structure which was transformed from a polycrystalline to single crystalline structure. The XRD pattern displayed features that are intermediate between the CdTe and CdSe, a sign of shell formation and not two separate compounds formed. This was also supported by high resolution transmission electron microscope images obtained. The crystallite sizes estimated using Scherrer formula were all less than 3 nm showing that the NPs are in quantum confinement regime. Scanning electron microscope was used to determine the surface topography while the energy X-ray dispersive spectrometer displayed the elemental composition of the as-prepared NPs. SEM and HRTEM images showed uniformly distributed spherical NPs with some agglomerations observed at longer duration of synthesis. The optical properties (photoluminescence (PL) and absorbance) investigated at different reaction times (20, 40, 60 and 80 min) presented novel features which show the formation of a thin CdSe shell on the CdTe core NPs. The PL emission wavelength was dramatically red shifted upon the growth of the CdSe shell on the CdTe core (from 541- 615 nm). Other unique features of the as-grown CdTe/CdSe NPs are discussed in detail. The obtained results displayed good material properties of the CdTe/CdSe NPs suitable for use in biomaging applications.

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“…In theoretical studies, it is common to use spherical shaped QDs, and many researchers have focused on the optical properties of this type of structure [3,6,[14][15][16]. Thanks to the rapid development of material growth techniques such as molecular beam epitaxy, metalorganic chemical vapor deposition and electron lithography and the advancement of chemical production processes, various dimensional new generation quantum nanostructures that allow electrons to be confined in these nanostructures have been produced, one of which is the coated spherical QDs called core/shell/shell QDs (CSSQDs) [17,18]. These structures consist of two semiconductors with different band gaps.…”

Section: Introductionmentioning

confidence: 99%

Effect of size modulation and donor position on intersubbands refractive index changes of a donor within a spherical core/shell/shell semiconductor quantum dot

Al¹

2021

Cumhuriyet Science Journal

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In the current study, linear, nonlinear and total relative refractive index changes of a single shallow hydrogenic donor atom confined in semiconductor core/shell/shell quantum dot heterostructure are investigated in detail by compact density matrix formalism. For this purpose, the energy eigenvalues and the corresponding wave functions are calculated by diagonalization method in the effective mass approximation. Then, intersubband 1 → 1 and 1 → 1 donor transition energies are calculated. In the study, the effects of core/shell sizes, donor position and depth of confinement potential are analyzed. The numerical results show that the linear and nonlinear refractive index changes undergo significant changes.

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Type‐ I and Type‐ II Core–Shell Quantum Dots: Synthesis and Characterization

Abstract: The sections in this article are Introduction Core–Shell UV ‐Vis Nanoparticulate Materials Type‐ I Core–Shell Structures Type‐ II Core–Shell Structures Multiple Shell … Show more

Cited by 11 publications

References 95 publications

Synthesis strategies and application of ternary quantum dots — in cancer therapy

Synthesis strategies and application of ternary quantum dots — in cancer therapy

Effects of growth time on the material properties of CdTe/CdSe core/shell nanoparticles prepared by a facile wet chemical route

Effect of size modulation and donor position on intersubbands refractive index changes of a donor within a spherical core/shell/shell semiconductor quantum dot

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