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1.
ACS Appl Mater Interfaces ; 16(24): 31045-31055, 2024 Jun 19.
Article in English | MEDLINE | ID: mdl-38857441

ABSTRACT

Photoexcited charge transfer dynamics in CdSe quantum dots (QDs) coupled with carbazole were explored to model QD-molecule systems for light-harvesting applications. The absorption spectra of QDs with different sizes, i.e., Cd35Se20X30L30 (T1), Cd56Se35X42L42 (T2), and Cd84Se56X56L56 (T3) were simulated with quantum dynamical methods, which qualitatively match the reported experimental spectra. The carbazole is attached with a 3-amino group at the apex position of T1 (namely T1-3A-Cz), establishing proper electronic communication between T1 and carbazole. The spectra of T1-3A-Cz is 0.22 eV red-shifted compared to T1. A time-dependent perturbation was applied in tune with the lowest energy peak (3.63 eV) of T1-3A-Cz to investigate the charge transfer dynamics, which revealed an ultrafast charge separation within the femtosecond time scale. The electronic structure showed a favorable energy alignment between T1 and carbazole in T1-3A-Cz. The LUMO of carbazole was situated below the conduction band of the QD, while the HOMO of carbazole mixed perfectly with the top of the valence band of the QD, developing the interfacial charge transfer states. These states promoted the photoexcited electron transfer directly from the CdSe core to carbazole. A rapid and enhanced charge separation occurred with the laser field strength increasing from 0.001 to 0.005 V/Å. However, T1 connected to the other positions of carbazole did not show charge separation effectively. The photoinduced charge transfer is negligible in the case of T2-carbazole systems due to poor electronic coupling, and it is not observed in T3-carbazole systems. So, the T1-3A-Cz model acts as a perfect donor-acceptor QD-molecule nanocomposite that can harvest photon energy efficiently. Further enhancement of charge transfer can be achieved by coupling more carbazoles to the T1 QD (e.g., T1-3A-Cz2) due to the extension of hole delocalization between T1 and the carbazoles.

2.
Small ; 20(35): e2400958, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38644328

ABSTRACT

Quantum dots (QDs) colloidal nanocrystals are attracting enduring interest by scientific communities for solar energy conversion due to generic physicochemical merits including substantial light absorption coefficient, quantum confinement effect, enriched catalytically active sites, and tunable electronic structure. However, photo-induced charge carriers of QDs suffer from ultra-short charge lifespan and poor stability, rendering controllable vectorial charge modulation and customizing robust and stable QDs artificial photosystems challenging. Herein, tailor-made oppositely charged transition metal chalcogenides quantum dots (TMCs QDs) and MXene quantum dots (MQDs) are judiciously harnessed as the building blocks for electrostatic layer-by-layer assembly buildup on the metal oxides (MOs) framework. In these exquisitely designed LbL assembles MOs/(TMCs QDs/MQDs)n heterostructured photoanodes, TMCs QDs layer acts as light-harvesting antennas, and MQDs layer serves as electron-capturing mediator to relay cascade electrons from TMCs QDs to the MOs substrate, thereby yielding the spatially ordered tandem charge transport chain and contributing to the significantly boosted charge separation over TMCs QDs and solar water oxidation efficiency of MOs/(TMCs QDs/MQDs)n photoanodes. The relationship between interface configuration and charge transfer characteristics is unambiguously unlocked, by which photoelectrochemical mechanism is elucidated. This work would provide inspiring ideas for precisely mediating interfacial charge transfer pathways over QDs toward solar energy conversion.

3.
J Hazard Mater ; 467: 133769, 2024 Apr 05.
Article in English | MEDLINE | ID: mdl-38359758

ABSTRACT

The widespread use of Cd-based quantum dots (Cd-QDs) has led to their inevitable release into the environment, and the prevalent iron oxides and natural organic matter (NOM) are the key factors affecting the environmental behavior and fate of Cd-QDs. However, the impact of NOM adsorbed on iron oxides on the behavior of Cd-QDs with iron oxides and the mechanism of its interaction are not clear. In this study, two kinds of water-soluble QDs (CdSe QDs and core-shell CdSe/ZnS QDs) were selected to study the aggregation and adsorption behavior on goethite (Goe) and goethite-humic acid/fulvic acid composites (Goe-HA/FA). Aggregation kinetics and adsorption experiments between QDs and Goe(-HA/FA), characterization, and extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory calculations indicated that electrostatic interaction was the dominant force for QDs adsorption on Goe(-HA/FA). HA/FA changed the surface charge of Goe and increased the electrostatic repulsion and steric hindrance between the particles, which in turn inhibited the adsorption of QDs on Goe. Besides, unsubstituted aromatic carbons, carboxy carbons, and carbonyl carbons played an important role in the adsorption process, and chemisorption occurred between QDs and Goe(-HA/FA). Our findings are important for better assessing the transport, fate, and potential environmental impacts and risks of Cd-QDs in iron-rich environments.

4.
Materials (Basel) ; 16(21)2023 Nov 01.
Article in English | MEDLINE | ID: mdl-37959604

ABSTRACT

Conventional single-component quantum dots (QDs) suffer from low recombination rates of photogenerated electrons and holes, which hinders their ability to meet the requirements for LED and laser applications. Therefore, it is urgent to design multicomponent heterojunction nanocrystals with these properties. Herein, we used CdSe quantum dot nanocrystals as a typical model, which were synthesized by means of a colloidal chemistry method at high temperatures. Then, CdS with a wide band gap was used to encapsulate the CdSe QDs, forming a CdSe@CdS core@shell heterojunction. Finally, the CdSe@CdS core@shell was modified through the growth of the ZnS shell to obtain CdSe@CdS@ZnS heterojunction nanocrystal hybrids. The morphologies, phases, structures and performance characteristics of CdSe@CdS@ZnS were evaluated using various analytical techniques, including transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy, fluorescence spectroscopy and time-resolved transient photoluminescence spectroscopy. The results show that the energy band structure is transformed from type II to type I after the ZnS growth. The photoluminescence lifetime increases from 41.4 ns to 88.8 ns and the photoluminescence quantum efficiency reaches 17.05% compared with that of pristine CdSe QDs. This paper provides a fundamental study and a new route for studying light-emitting devices and biological imaging based on multicomponent QDs.

5.
Mikrochim Acta ; 190(8): 326, 2023 Jul 26.
Article in English | MEDLINE | ID: mdl-37495856

ABSTRACT

A fluorescent microgel for BPA detection has been successfully prepared by cross-linking linear poly(styrene-co-glycidyl methacrylate) (poly (STY-co-GMA)) with L-cysteine-capped CdSe quantum dots (Lcys-caped CdSe QDs). The microgel contained specific binding sites created by the covalent grafting of the copolymer onto the QDs via the GMA units, allowing for selective trapping of BPA molecules through π-π and hydrogen bond interactions with phenyl, carboxylic, and amine groups. After binding, electron transfer from the QDs to the analyte quenched the fluorescence at a wavelength of 547 nm when excited at 400 nm. The rational compositional and structural design allows the microgel to accurately detect BPA concentrations over a wide dynamic range of 1.0×10-1 to 1.0×105 µg/L with a low detection limit (7.0×10-2 to 8.0×10-2 µg/L) in deionized, drinking, and tap waters within just 2.0 min. On top of that, the sensitivity for BPA detection was 2.0-4.6 times higher than that of the other 3 structural analogues, even molecular imprinting was not involved. The influence of the STY/GMA compositions in the copolymers and environmental conditions, including pH and ionic strength, on the sensing performance was determined. Moreover, the sensing mechanism and the selectivity with respect to the molecular features were elucidated.

6.
Spectrochim Acta A Mol Biomol Spectrosc ; 290: 122302, 2023 Apr 05.
Article in English | MEDLINE | ID: mdl-36603280

ABSTRACT

With the widespread application of Ag+ in modern life and industry, the potential hazardous effects of Ag+ to environment and humans have attracted great concerns. Thus, effective and rapid strategies for Ag+ detection are highly desirable. In this paper, a novel ratiometric fluorescence sensor using CdSe quantum dots (QDs) has been constructed for sensitive and selective detection of Ag+, which is based on the formation of Ag2Se QDs. CdSe QDs were initially prepared and showed single wavelength emission at 510 nm. When Ag+ exists, a rising peak appeared at 650 nm and the emission at 510 nm declined, exhibiting distinct ratiometric fluorescence emission (I650/I510) characteristic with a linear response over the Ag+ concentration range of 0.01-4 µM. Significantly, the fluorescence changed from green to red. The detection limit of the constructed sensor is 1.4 nM. Furthermore, the sensing assay can be successfully applied to detect Ag+ in real water samples and living cells.


Subject(s)
Cadmium Compounds , Quantum Dots , Selenium Compounds , Humans , Fluorescent Dyes , Spectrometry, Fluorescence , Limit of Detection
7.
Spectrochim Acta A Mol Biomol Spectrosc ; 287(Pt 1): 122064, 2023 Feb 15.
Article in English | MEDLINE | ID: mdl-36347165

ABSTRACT

In this paper, water-soluble cysteamine (CA)-capping CdSe quantum dots (CA-CdSe) could be used as a continuous fluorescent sensor. The CA-CdSe QDs can respond to Ag+ with a detection limit of 54.1 nM. Interestingly, CA-CdSe quantum dots combined with Ag+ to generate a new nano-fluorescence sensor-Ag+ modified CA-CdSe QDs (Ag+@CA-CdSe). Ag+@CA-CdSe can detect glutathione (GSH) with good sensitivity and anti-interference performance. The detection limit of Ag+@CA-CdSe fluorescenct sensor for GSH is as low as 0.74 µM. In addition, the novel nano-fluorescent sensor Ag+@CA-CdSe exhibited good cell permeability and was successfully applied to detect exogenous and endogenous GSH concentrations in cells. It could distinguish cancerous and normal cells by in vitro cell fluorescence imaging.


Subject(s)
Neoplasms , Quantum Dots , Fluorescent Dyes , Glutathione , Spectrometry, Fluorescence/methods , Cysteamine
8.
ACS Nano ; 16(11): 18838-18848, 2022 Nov 22.
Article in English | MEDLINE | ID: mdl-36317947

ABSTRACT

The coherent spin dynamics of electrons in CdSe nanocrystals embedded in a glass matrix with diameters from 3.3 up to 6.1 nm are investigated by time-resolved Faraday ellipticity at room and cryogenic temperatures. Only one Larmor precession frequency is detected, which corresponds to the larger of the two precession frequencies and thus g-factor values found in the typical signal from solution-grown colloidal CdSe nanocrystals. We identify this frequency accordingly as associated with the spin precession of resident electrons localized in the nanocrystals in the vicinity of the surface. We provide a detailed theoretical analysis of the exciton level spin structure in the magnetic field and model the spin dynamics in CdSe nanocrystals of different symmetries. This allows us to exclude the exciton as the origin of the experimentally observed oscillating signal. At a cryogenic temperature of 6 K, an additional nonoscillating component emerges in the spin dynamics. We consider several possible origins of this signal and conclude that it is related to the hole spin polarization.

9.
J Mol Model ; 28(8): 220, 2022 Jul 13.
Article in English | MEDLINE | ID: mdl-35831761

ABSTRACT

In this work, eight van der Waals heterojunctions based on CdSe or CdSe-ZnS quantum dots (QDs) and four commonly used two-dimensional transition metal dichalcogenides (2D-TMDs) are theoretically designed. On the basis of the constructed structures, density functional theory (DFT) method is employed to investigate the structural and optoelectronic related properties of these heterojunctions in detail. Specifically, their electronic properties including charge density differences, density of states, and band offsets are calculated, based on which band alignment types as well as their potentials as novel photovoltaic materials are discussed. According to these calculations, we proposed that several van der Waals heterostructures including MoS2/CdSe, MoTe2/CdSe, WSe2/CdSe, MoTe2/CdSe-ZnS, and WSe2/CdSe-ZnS might be used as potential photovoltaic materials due to their type II band alignment characteristics. Moreover, the WSe2/CdSe-ZnS heterostructure is expected to have optimal photovoltaic performance attributed to their large bond offsets and band gaps, which could not only facilitate charge separation processes, but also slow down charge recombination. Our present theoretical work could be helpful for the future experimental design of novel CdSe QDs and 2D-TMD based van der Waals heterostructures with excellent photovoltaic performances.

10.
ACS Appl Mater Interfaces ; 14(26): 29945-29955, 2022 Jul 06.
Article in English | MEDLINE | ID: mdl-35749254

ABSTRACT

Colloidal quantum dots (QDs) as photocatalysts enable catalysis of CO2-to-CO conversion in the presence of electron donors. The surface and/or interfacial chemical environment of the QDs is essential for the activity and selectivity of the CO2 photoreduction. Various strategies, including exposing active metal sites or anchoring functional organic ligands, have been applied to tune the QDs' surface chemical environment and thus to improve both activity and selectivity of CO2 photoreduction, which occurs at surface of the QDs. However, the efficient and selective photocatalytic CO2 reduction with QD photocatalysts in water is still a challenging task due to low CO2 solubility and robust competing reaction of proton reduction in water. Different from state-of-the-art QDs' surface manipulation, we proposed to ameliorate the interfacial chemical environment of CdSe QDs via assembling the QDs into functional polymeric micelles in water. Herein, CdSe@PEI-LA assemblies were constructed by loading CdSe QDs into polymeric micelles formed by PEI-LA, a polyethylenimine (PEI)-based functional amphiphilic polymer. Due to self-assembly and high CO2 adsorption capacity of PEI-LA in water, the photocatalytic CO2-to-CO conversion efficiency and selectivity of the CdSe@PEI-LA assemblies in water were dramatically improved to 28.0 mmol g-1 and 87.5%, respectively. These two values increased 57 times and 1.5 times, respectively, compared with those of the pristine CdSe QDs. Mechanism studies revealed that CdSe QDs locate in polymeric micelles of high CO2 local concentration and the photoinduced electron transfer from the conduction band of CdSe QDs to Cd-CO2* species is thermodynamically and kinetically improved in the presence of PEI-LA. The CdSe@PEI-LA system represents a successful example of using a functionalized amphiphilic polymer to ameliorate interfacial microenvironments of nanocrystal photocatalysts and realizing efficient and selective CO2 photoreduction in water.

11.
Nanomaterials (Basel) ; 12(3)2022 Jan 29.
Article in English | MEDLINE | ID: mdl-35159829

ABSTRACT

CdSe quantum dots nanoparticles were coated with the thiolated (DiAminoButane based dendrimer) DAB dendrimer of fifth generation (S-DAB5) and embedded in a highly hydrophilic regenerated cellulose (RC) film by simple dip-coating method (immersion in QD-dendrimer aqueous solution) as a way to get a flexible nano-engineered film (RC-4/CdSe-QDs@S-DAB5) with high transparency and photoluminescence properties for different applications. Optical changes in the RC film associated with QDs inclusion were determined by spectroscopic ellipsometry (SE) measurements, which provide information on changes caused in the refraction index and the extinction coefficients of the film, as well as by light transmittance/reflectance curves and photoluminescence (PL) spectra. Impedance spectroscopy (IS) and other typical physicochemical techniques for material characterization (TEM, SEM and XPS) have also been used in order to have more complete information on film characteristics. A comparison of RC-4/CdSe-QDs@S-DAB5 film optical characteristics with those exhibited by other RC-modified films depending on the type of dendrimer was also carried out.

12.
Adv Sci (Weinh) ; 9(2): e2102530, 2022 Jan.
Article in English | MEDLINE | ID: mdl-34859614

ABSTRACT

Artificial Z-scheme, a tandem structure with two-step excitation process, has gained significant attention in energy production and environmental remediation. By effectively connecting and matching the band-gaps of two different photosystems, it is significant to utilize more photons for excellent photoactivity. Herein, a novel one-photon (same energy-two-photon) Z-scheme system is constructed between rGO modified boron-nitrogen co-doped-WO3 , and coupled CdSe quantum dots-(QDs). The coctalyst-0.5%Rhx Cr2 O3 (0.5RCr) modified amount-optimized sample 6%CdSe/1%rGO3%BN-WO3 revealed an unprecedented visible-light driven overall-water-splitting to produce ≈51 µmol h-1 g-1 H2 and 25.5 µmol h-1 g-1 O2 , and it remained unchanged for 5 runs in 30 h. This superior performance is ascribed to the one-photon Z-scheme, which simultaneously stimulates a two photocatalysts system, and enhanced charge separation as revealed by various spectroscopy techniques. The density-functional theory is further utilized to understand the origin of this performance enhancement. This work provides a feasible strategy for constructing an efficient one-photon Z-scheme for practical applications.

13.
Food Chem ; 366: 130590, 2022 Jan 01.
Article in English | MEDLINE | ID: mdl-34311230

ABSTRACT

A paper-based electrochemiluminescence device (µPAD-ECL) for the estimation of trimethylamine (TMA) concentration in fish was developed using tris(2,2'-bipyridyl)ruthenium(II) complex coupled with water soluble thioglycolic acid-capped CdSe quantum dots on the inkjet-printed paper-based device. The quenching effect of tertiary amines on the ECL intensity was found to be sensitive and concentration dependent. This effect allows the measurement of TMA at low concentrations. Under the optimal conditions, the linear concentration range was exhibited from 1 × 10-12 to 1 × 10-7 M and a detection limit of 2.09 × 10-13 M, with relative standard deviation of 1.97 %. The applicability of µPAD-ECL is demonstrated by the rapid estimation of trimethylamine concentration in fish tissue, and could be used as a method for screening the total amount of tertiary amines in fishery products in remote communities. The results obtained using the paper-based devices agreed well with those obtained applying high performance liquid chromatography with benzoyl derivatization, at a confidence level of 95%.


Subject(s)
Cadmium Compounds , Quantum Dots , Animals , Luminescent Measurements , Methylamines , Selenium Compounds , Thioglycolates
14.
Nanomaterials (Basel) ; 11(10)2021 Sep 28.
Article in English | MEDLINE | ID: mdl-34684972

ABSTRACT

The photophysical properties of Cu-doped CdSe quantum dots (QDs) can be affected by the oxidation state of Cu impurity, but disagreement still exists on the Cu oxidation state (+1 or +2) in these QDs, which is debated and poorly understood for many years. In this work, by using density functional theory (DFT)-based calculations with the Heyd-Scuseria-Ernzerhof (HSE) screened hybrid functional, we clearly demonstrate that the incorporation of Cu dopants into the surface of the magic sized Cd33Se33 QD leads to non-magnetic Cu 3d orbitals distribution and Cu+1 oxidation state, while doping Cu atoms in the core region of QDs can lead to both Cu+1 and Cu+2 oxidation states, depending on the local environment of Cu atoms in the QDs. In addition, it is found that the optical absorption of the Cu-doped Cd33Se33 QD in the visible region is mainly affected by Cu concentration, while the absorption in the infrared regime is closely related to the oxidation state of Cu. The present results enable us to use the doping of Cu impurity in CdSe QDs to achieve special photophysical properties for their applications in high-efficiency photovoltaic devices. The methods used here to resolve the electronic and optical properties of Cu-doped CdSe QDs can be extended to other II-VI semiconductor QDs incorporating transition-metal ions with variable valence.

15.
ACS Nano ; 15(10): 16411-16421, 2021 Oct 26.
Article in English | MEDLINE | ID: mdl-34617734

ABSTRACT

CdSe nanocrystals (NCs) were grafted on chiral silica nanoribbons, and the mechanism of resulting chirality induction was investigated. Because of their chiral organization, these NCs show optically active properties that depend strongly on their grafting densities and sizes of the NCs. The effect of the morphology of the chiral silica templates between helical (cylindrical curvature) vs twisted (saddle like curvature) ribbons was investigated. The g-factor of NCs-silica helical ribbons is larger than that of the NCs-silica twisted ribbons. Finally, rod-like NCs (QR) with different lengths were grafted on the twisted silica ribbons. Interestingly, their grafting direction with respect to the helix surface changed from side-grafting for short QR to tip-grafting for long rods and the corresponding CD spectra switched signs.

16.
ACS Sens ; 6(7): 2605-2612, 2021 07 23.
Article in English | MEDLINE | ID: mdl-34076410

ABSTRACT

The social impact of virus spread is immeasurable. Vaccine prophylaxes take considerable time to develop because clinical trials are required. The best initial response to an emerging virus is establishing a virus detection technology adapted by simply preparing virus-specific antibodies. A virus detection system that detects two signals from one analyte has been developed to detect the target virus more sensitively and reliably. Plasmon regions on the surface of nanoparticles are effective in enhancing optical and electrochemical signals. Thus, CdSeTeS quantum dots (QDs) have been used as optical and electrochemical signal-generating materials. In contrast, gold nanoparticle-magnetic nanoparticle-carbon nanotube (AuNP-MNP-CNT) nanocomposites are used for the magnetic separation of the virus from interferences and for signal enhancement. In the presence of the target virus, the QDs optically show a virus concentration-dependent fluorescence enhancement effect due to the localized surface plasmon resonance (LSPR) of AuNPs. Regarding the electrochemical signal, Cd ions eluted by acid degradation of the QDs in solution show a virus concentration-dependent increase in the current peak on an electrode whose electrochemical properties are improved by the deposition of these nanocomposites. Both nanomaterials are conjugated with antibodies specific to influenza virus A (IFV/A), binding this target in a sandwich structure. We are successfully detecting the virus from these two signals during actual virus detection, even when the virus particles are in a human serum matrix. The limit of detection is 2.16 fg/mL for optical detection and 13.66 fg/mL for electrochemical detection.


Subject(s)
Biosensing Techniques , Metal Nanoparticles , Nanocomposites , Gold , Humans , Surface Plasmon Resonance
17.
Spectrochim Acta A Mol Biomol Spectrosc ; 250: 119369, 2021 Apr 05.
Article in English | MEDLINE | ID: mdl-33406453

ABSTRACT

In this study cadmium selenium quantum dots (CdSe QDs) were synthesized with different capping agents namely, l-cysteine, mercaptosuccinic acid and thioglycolic in aqueous solution. The effect of capping agent on the nucleation and particle growth process was investigated. Electronic absorption and emission fluorescence spectroscopy techniques were applied to map out the size evolution of the QDs. The methods of SEM, EDX, XRD and FTIR were also used for characterization of the prepared samples. The average diameters of the synthesized quantum dots were estimated using different methods. Results revealed that the order of particles size was obtained as follow: CdSe-MSA > CdSe-LCY > CdSe-TGA. Results also showed that the TGA has the strongest binding ability with the QDs surface; in contrast MSA has the weakest binding ability. Results indicated that there is a mutual relationship between changing the bandwidth and the rate of growing particle size of the quantum dot, so that the particles with slow growing rate (CdSe-TGA, 12 h) its bandwidth varies smoothly. Also the magnitude of bandwidth of the spectrum is fairly dependent to the size of the CdSe QDs during the growth process. The quantum dots with larger size (CdSe-MSA) have the fluorescence spectra with broader bandwidth. The trend of the particles growth was discussed in details. Results revealed that the kind of capping agents are considerably influence on the nucleation as well as particle growth processes.

18.
J Colloid Interface Sci ; 586: 640-646, 2021 Mar 15.
Article in English | MEDLINE | ID: mdl-33183753

ABSTRACT

The charge recombination on the interfaces of TiO2/quantum dots (QDs)/electrolyte is a key factor limiting the efficiency of quantum dot-sensitized solar cells (QDSSCs). Construction of double-layer barrier structure of ZnS/QDs/ZnS is a vital strategy to suppress the interfacial charge recombination. However, a large lattice mismatch (12%) at CdSe/ZnS interfaces causes CdSe to grow slowly on TiO2/ZnS mesoporous film, weakening the interaction between QDs and mesoporous film, which reducing the efficiency of CdSe QDSSCs with double ZnS barrier layers. Applying a voltage of 2 V in successive ionic layer adsorption reaction (VASILAR) to create an electric field, which assists Cd2+ and SeSO32- ions rapidly diffuse into the TiO2/ZnS mesoporous film to react forming CdSe QDs at room temperature. Optimizing the number of CdSe QDs deposition layers and combine with ZnS double-layer barrier structure, a best PCE of 4.34% for ZnS/CdSe/ZnS QDSSCs is achieved. This study gives a fast and simple approach to inhibit interfacial charge recombination to construct high performance CdSe QDSSCs.

19.
Nanomedicine ; 30: 102299, 2020 11.
Article in English | MEDLINE | ID: mdl-32931928

ABSTRACT

In recent years quantum dots (QDs) have risen as useful luminescent nanoparticles with multiple applications ranging from laser, image displays and biomedical applications. Here we review and discuss the studies of these nanoparticles in patient derived cellular samples or tissues, including cellular models from iPSCs from patients, biopsied and post-mortem tissue. QD-based multiplexed imaging has been proved to overcome most of the major drawbacks of conventional techniques, exhibiting higher sensitivity, reliability, accuracy and simultaneous labeling of key biomarkers. In this sense, QDs are very promising tools to be further used in clinical applications including diagnosis and therapy approaches. Analyzing the possibilities of these materials in these biological samples gives an overview of the future applications of the nanoparticles in models closer to patients and their specific disease.


Subject(s)
Cadmium Compounds/chemistry , Models, Biological , Quantum Dots/chemistry , Selenium Compounds/chemistry , Cadmium Compounds/toxicity , Female , Humans , Male , Neoplasms/pathology , Quantum Dots/toxicity , Reproducibility of Results , Selenium Compounds/toxicity
20.
Molecules ; 25(17)2020 Aug 31.
Article in English | MEDLINE | ID: mdl-32878143

ABSTRACT

Most previous studies of perovskite core/shell structures have been based on ZnO/TiO2 nanowires (NWs), which are not suitable for high photoelectric conversion efficiency. Here, core/shell ZnO/TiO2 NWs with AgCl-doped CdSe quantum dots were fabricated as an electron transport layer (ETL) for perovskite solar cells, based on ZnO/TiO2 arrays. We designed CdSe with AgCl dopants that were synthesized by a colloidal process. An improvement of the recombination barrier (Rct1), due to shell supplementation with AgCl-doped CdSe quantum dots, improved the open circuit voltage, the fill factor, and the adsorption capacity of CH3NH3PbI3 perovskite with NWs. The enhanced cell steady state was attributable to TiO2 with AgCl-doped CdSe QD supplementation. A maximum power conversion efficiency of 15.12% was attained in an atmospheric environment. The mechanism of the recombination and electron transport in the perovskite solar cells becoming the basis of ZnO/TiO2 core/shell arrays was investigated to represent the merit of ZnO/TiO2 core/shell arrays as an electron transport layer in effective devices. These results showed an uncomplicated approach for restraining non-radiative recombination loss in hetero-structure core/shell arrays to significantly improve perovskite solar cell performance and increase the effectiveness of photovoltaics.


Subject(s)
Nanowires/chemistry , Quantum Dots , Selenium Compounds/chemistry , Silver Compounds/chemistry , Titanium/chemistry , Zinc Oxide/chemistry , Electric Power Supplies , Electron Transport , Nanowires/ultrastructure , Spectrum Analysis
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