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In order to improve the tribological properties of graphene reinforced polymer composites, ionic liquids (IL) and carbon quantum dots (CQDs) were deposited on the reduced graphene oxide (rGO) nanosheets surface to ameliorate the compatibility between graphene and bismaleimide (BMI) matrix, as well as the stability of their self-lubricating transfer films. Their tribological properties were evaluated, and the wear mechanism was studied by means of surface/interface analysis, respectively. It could be found that CQDs/IL/rGO could improve the stability of the friction coefficient and decrease the volume wear rate of their BMI composites. When the filler amount was only 0.6 wt%, the friction coefficient and volume wear rate of CQDs/IL/rGO/BMI composites decreased by 41.2% and 94.7% compared with the neat BMI, respectively. Also, the CQDs/IL/rGO/BMI composites exhibited the lowest friction coefficient fluctuations and volume wear rate than those of other composites. Because of the synergistic effects of the CQDs, IL and rGO, uniform, continuous and steady self-lubricating transfer film could be formed during the friction process, thus significantly improving the anti-friction and wear-resistance properties of CQDs/IL/rGO/BMI composites. More importantly, the unique combinations of advantages of each functional component can also be applied in many other fields, such as catalysis, chemical sensors, etc. [Display omitted] • CQDs and ILs synergistically modify graphene can significantly improve tribological properties of their composites. • Because of the synergistic effects of the CQDs, IL and rGO, high quality self-lubricating transfer film can be formed. • Abundant tribo-chemical reactions enhance the durability of the transfer film of CQDs/IL/rGO/BMI composites. [ABSTRACT FROM AUTHOR]

Se2− color centers and CdSe/Cd1−xZnxSe quantum dots (QDs) were formed in silicate glasses, respectively, by carefully adjusting the content of Al2O3. The absorption coefficient and broad visible emission at 400‐700 nm of Se2− color centers increased firstly and then decreased upon increasing concentration of Al2O3 from 0 to 5 mol. %. With 2 mol. % Al2O3 adding, the band edge emission centered at 497 nm from CdSe QDs in glasses was observed after heat treatment. Raman spectra and TEM characterization confirmed the formation of CdSe/Cd1−xZnxSe QDs. The small amount addition of Al2O3 had a significant effect on the formation of Se2− color centers and precipitation of CdSe/Cd1−xZnxSe QDs in glasses due to its complicated effect on the network structure and optical basicity of the glasses. [ABSTRACT FROM AUTHOR]

Abstract: In order to alleviate the effect of the surface defects on the emission properties of quantum dots, copper ions‐doped ZnSe quantum dots (QDs) in the glasses are prepared using melt‐quenching and subsequent thermal annealing methods. For glasses without copper doping, tunable band‐edge emission from ZnSe QDs is achieved. For glasses with copper doping, efficient energy transfer from ZnSe QDs to copper ions is observed, and efficient broad band emission from copper ions is realized at the expense of the band‐edge emission of ZnSe QDs. Absorption spectra, size‐dependent broad‐band emission spectra and electron spin resonance spectra show the cupric ions are doped into the ZnSe QDs. Results reported here shows that doping of transition‐metal ions into semiconductor QDs in glasses is promising for development of high efficient luminescent glasses. [ABSTRACT FROM AUTHOR]

Glass with the composition of 50SiO 2 -25Na 2 O-10ZnO-10BaO-5Al 2 O 3 (in mol%) was used as the matrix for the growth of PbSe QDs. The viscosity-temperature relations of the glass were obtained through Vogel-Tammann-Fulcher equation. PbSe QDs were precipitated in this silicate glasses with the heat-treatment temperatures ( T H ) ranging from 490 to 540 °C for fixed duration of 10 h, corresponding to the glass-viscosity 10 11.2 –10 8.9 Pa·s. Meanwhile, the absorption peaks from PbSe QDs shifted from 872 nm to 2134 nm, and the PL peaks shifted from 1104 nm to 2185 nm. To study the PbSe QDs growth kinetics, the glasses were heat treated at 500, 520 and 540 °C for 1–20 h. Changes in diameter of PbSe QDs exhibited strong time dependencies (i.e. D ~ t 0.17 , T H = 520 °C), while the time dependencies were much smaller than that predicted by the classical Lifshitz-Slyozov-Wagner (LSW) theory (D ~ t 1/3 ) and the higher T H leads to the smaller growth exponent. [ABSTRACT FROM AUTHOR]

CdS/Cd 1−x Zn x S sandwich-structured quantum dots (QDs) were precipitated in silicate glasses with high quantum efficiency up to 53%. The QDs were composed by a CdS core with a Cd 1−x Zn x S shell of about 1–3 nm in thickness through heat-treatment at 550 °C for 10 h. With the increased heat-treatment temperature, the intensity ratio between the intrinsic emission and the defects emission increased and the Stokes shift decreased from 84 to 4 meV, which was caused by both the increased size and passivated surface defects of the QDs. [ABSTRACT FROM AUTHOR]

Lead selenide (PbSe) quantum dots (QDs) doped with Sr 2 + were precipitated in silicate glasses. The absorption and photoluminescence (PL) bands of the glasses blue-shifted as SrO concentration increased. These changes resulted mainly because Sr incorporation increased the band gap of PbSe nanocrystals. After heat treatment at 520 °C for 10 h, mean QD diameters were similar before and after the addition of SrO: ~ 7.2 nm with 0% SrO and ~ 6.9 nm with 10 mol% SrO. However, these two glasses show the absorption bands at 1743 nm and 1246 nm, and PL bands at 1803 and 1370 nm, respectively. These large shifts are due to the increase in the band gap through the formation of Pb 1 − x Sr x Se mixed-type QDs. One typical chemical composition of QDs formed in a glass with 10 mol% SrO after heat treatment at 520 °C for 10 h is Pb 0.89 Sr 0.11 Se with a band gap of ~ 0.58 eV. [ABSTRACT FROM AUTHOR]

Infrared photoluminescence (PL) properties of Sn-modified PbSe quantum dots (QDs) in silicate glass were investigated. The QDs' sizes were controlled by changing the heat treatment temperatures. The longest absorption peak from Sn-modified PbSe QDs was centered at 2590 nm, and the PL band extended to 2650 nm. X-ray diffraction peaks indicated that the PbSe QDs formed in the glass matrix although low Sn content resulted in no obvious difference between PbSe QDs and Sn-modified PbSe QDs. Sn was found in QDs that proves the incorporation of Sn into PbSe QDs. The proposed composition of the Sn-modified PbSe QDs was Pb 0.92 Sn 0.08 Se with a band gap of ~ 0.13 eV; the small amount of Sn changed the energy structure of QDs, narrowed the band-gap, and increased the PL emission wavelength. [ABSTRACT FROM AUTHOR]

ZnSe and ZnS nanocrystals (NCs) were precipitated in glasses through heat-treatment. High resolution transmission electron microscope image confirmed that ZnSe NCs were formed in the silicate glasses, and the X-ray diffraction patterns confirmed that ZnS NCs were precipitated in the borosilicate glasses. Absorption shoulders of the ZnSe NCs and ZnS NCs appeared at ~ 2.76 eV and ~ 3.78 eV, corresponding to the bandgap energies of bulk ZnSe and ZnS crystals, respectively. Instead of the intrinsic emissions, broad-band visible photoluminescence from the surface defects or color centers in the glasses was observed from these ZnSe or ZnS NCs. [ABSTRACT FROM AUTHOR]

Modulation of the band gap energy and diameter of quantum dots (QDs) formed in glasses is important to achieve the optimized performance for applications as infrared light sources, lasers, saturable absorbers, etc. Absorption and photoluminescence of PbS QDs were extended into mid-infrared wavelength range in glasses containing small amount of lead but oversaturated with sulfur. Dual-band photoluminescence of PbSe QDs was prepared in oxyfluoride glass-ceramics containing BaF2 nanocrystals. By introducing SnO in the glasses, alloyed Pb1-xSnxSe QDs with smaller band gap energies were formed in glasses, and mid-infrared photoluminescence of Pb1-xSnxSe QDs at ~2570 nm in wavelength was achieved. [ABSTRACT FROM AUTHOR]

Size-dependent Stokes shift of PbS quantum dots (QDs) formed in the glasses was investigated. PbS QDs with diameters of 3.5 nm to 13.3 nm were precipitated in silicate glasses with different S/Pb ratios using the conventional thermal treatment method. Absorption and photoluminescence (PL) of PbS QDs were tuned from ~0.9 µm (1.38 eV) to ~2.3 µm (0.54 eV) by adjusting the diameters of PbS QDs from 3.5 nm to 13.3 nm. PL energies of QDs exhibited linear dependence on the absorption energies with a slope of 0.484 for PbS QDs with band gap energies larger than 0.98 eV, and the maximum Stokes shift was found to be 206.2 meV for 3.5 nm-sized PbS QDs. For large PbS QDs with band gap energies smaller than 0.98 eV, Stokes shift was found to be ~20 meV or smaller. The size-dependent Stokes shift indicated that surface defects made the main contribution and relative energy positions of these surface defects were strongly dependent on the size of PbS QDs. [ABSTRACT FROM AUTHOR]

The influence of Nd3+ ions was investigated on the precipitation and optical properties of PbS quantum dots ( QDs) inside silicate glasses. The diameters of the PbS QDs decreased as the concentration of Nd3+ in the glass increased as evidenced by blue shifts in the absorption and photoluminescence spectra. Electron energy loss spectroscopy shows that Nd3+ ions exist preferentially inside the PbS nanocrystals rather than in the glass matrix. We postulate that Nd-O clusters are preserved during heat treatment and serve as nucleation sites for PbS crystals. No change in the local bonding scheme of the Nd3+ ions was observed following heat treatment. [ABSTRACT FROM AUTHOR]

We fabricated a new porous silicon photonic device which is a special multi-layer porous silicon including two different single layer porous silicon and a porous silicon Bragg mirror, and investigated the influence of porous silicon Bragg mirror's structure on the fluorescence intensity of quantum dots (QDs) which infiltrated into porous silicon device, and CdSe/ZnS QDs we used emit at 605 nm and 625 nm respectively. By immersing porous silicon samples in QDs solution, QDs were successfully infiltrated into porous silicon devices which have high reflection band at or beyond fluorescence peak. Experimental results show that the fluorescence intensity of QDs which infiltrated into the first layer of porous silicon device can be enhanced when fluorescence peak falls into the high reflection band of porous silicon device. [ABSTRACT FROM AUTHOR]

Incorporating quantum dots (QDs) into dendritic mesoporous silica nanoparticles (DMSNs) for signal amplification of label materials represents an efficient strategy to improve the performance of lateral flow immunoassays (LFIAs). In this work, it is found that the CdSe/ZnS QD's size matters for balancing their loading amount and quantum yields (QYs) in the DMSNs-QDs based label materials and ultimately determining the performance of LFIA. The impacts of three CdSe/ZnS QDs with diameters of 9.1, 10.5 and 11.7 nm on CdSe/ZnS QDs incorporation and LFIA applications are studied. The increase of CdSe/ZnS QDs size from 9.1 to 11.7 nm results in a decrease in CdSe/ZnS QDs loading amount and an increase in QYs of incorporated CdSe/ZnS QDs. This trade-off leads to an optimized CdSe/ZnS QDs size of 10.5 nm, which exhibits the best LFIA performance due to the balanced QDs loading (2.26 g g−1) and QY (57.1%). The 10.5 nm CdSe/ZnS QDs incorporated DMSNs-QDs for C-reactive protein (CRP) detection achieved a limit of detection of 5 pg mL−1 (equivalent to 4.2 × 10−14 M) with naked eye, which is lower than literature reports and commercial LFIA products. This study demonstrates that the CdSe/ZnS QD's size matters for improving the quality of DMSNs-QDs and their LFIA performance for CRP determination, providing new insights into the rational design of advanced label materials for improving LFIA performance. • The first report on the importance of QDs' size for improving LFIA performance. • The increase of QDs size from 9.1 to 11.7 nm results in a decrease in QDs loading and an increase in QYs of loaded QDs. • The DMSNs-QDs based LFIA for CRP achieved the best limit of detection at 5 pg mL−1 with naked eye. • Our study provides new perspectives for rational design of QDs-based labels for LFIA signal amplification. [ABSTRACT FROM AUTHOR]

Distribution and roles of rare earth ions in fluoride nanocrystals and lead chalcogenide quantum dots formed in glasses are reported. High-resolution transmission electron microscopic analysis and electron energy loss spectroscopic ( EELS) analysis showed that oxyfluoride glasses initially form crystals with high Er3+ content such as PbErF5 during heating and gradually form crystals with low Er3+ concentration. Amount of PbErF5 crystals depended upon the initial concentration of Er3+ ions in the parent glasses. EELS analysis also showed that Nd3+ ions were formed inside PbS quantum dots, supporting the proposition of the formation of Nd-O clusters. [ABSTRACT FROM AUTHOR]

Formation of PbS QDs in the glasses containing a small amount of lead oxide was examined. Oversaturation of sulfur only was sufficient to promote the formation of PbS QDs in the glasses. Upon thermal treatment, absorption of PbS QDs was tuned from 824nm to 2213nm. Infrared photoluminescence, especially, mid-infrared photoluminescence from PbS QDs was observed in the range of 1008nm to 2182nm. Ostwald ripening of PbS QDs occurred when the heat-treatment temperature was 530°C or 540°C, and led to the decrease in the absorption coefficients and splitting of the photoluminescence bands. [ABSTRACT FROM AUTHOR]

Tunable absorption and photoluminescence ( PL) of lead chalcogenide quantum dots ( QDs) doped in glasses due to the quantum confinements effect have been actively investigated for application as saturable absorbers, laser sources, and fiber-optic amplifiers. Optical properties of QDs have been carefully monitored by controlling their sizes through heat treatment and rare-earth ion doping. Two- and three-dimensional precipitation of lead chalcogenide QDs were also realized using silver ion exchange and femtosecond laser irradiation in combination with thermal treatment. Prototypes of microstructured single-mode fibers and tapered fiber amplifiers containing QDs proved potentials of these materials for fiber-optic amplifiers application. Further research works on QD-doped solid core fibers, surface passivation of quantum dots and their application for the mid-infrared optical devices are necessary. [ABSTRACT FROM AUTHOR]

Abstract: Optical properties of PbS quantum dots (QDs) precipitated inside the oxide glass matrix were investigated. Photoluminescence (PL) from the PbS QDs showed peak wavelengths located at 1170–1680nm with widths of 150–550nm. Radii of QDs in glasses were 2.3–4.7nm depending upon the thermal treatment. Peak wavelengths of PL bands shifted as much as 70nm as the temperatures and excitation irradiances increased. Calculated effective local temperatures indicated that these shifts of PL spectra were associated with local heating induced by the temperatures and laser beam. [Copyright &y& Elsevier]

Abstract: We report the effects of laser-induced blue-shift of the photoluminescence from PbS quantum dots embedded in the glass matrix. When the excitation irradiance increased from 70 to 850W/cm2, photoluminescence bands from the PbS quantum dots underwent a blue-shift of ∼60meV. At the same time, the values of the full width at half maximum (FWHM) intensities increased from 76 to 117meV. These changes were due to the increase in the local temperatures induced by the excitation beam. [Copyright &y& Elsevier]

Abstract: The Rashba interaction in the low-dimensional semiconductor systems, which plays an important role in the spintronics, can be regarded as an external Yang–Mills field. With this viewpoint, the gauge field in a one dimensional (1D)-ring in the presence of the Rashba interaction can be reduced into two independent U(1) fields through an SU(2) transformation, which can also be extended to arbitrary 1D Rashba system. As an instance, a two-arms spin interferometer with a quantum dot embedded in one of its arms is considered. By tuning the Rashba interaction, the oscillation of the spin polarization of the current is predicted. Another application is about the persistent spin current in a Rashba ring. Keep the SU(2) gauge field in mind, it is straightforward to find that the persistent spin current may result from the Rashba interaction. [Copyright &y& Elsevier]

PbS QDs of ~ 5nm diameter were precipitated in glasses containing Ag nanoparticles after 3 min of 1.5-W continuous-wave laser illumination at λ = 532 nm. Photoluminescence spectra of the PbS QDs recorded in the 1.3~1.6 μm wavelength region revealed conversion of photon energy to thermal energy by surface plasmon resonance. Laser-assisted local heating around Ag NPs can provide a new method to control the spatial distribution of QDs in glasses. [ABSTRACT FROM AUTHOR]

Functional nanoparticles (NPs) hold immense promise in diverse fields due to their unique biological, chemical, and physical properties associated with size or morphology. Microfluidic technologies featuring precise fluid manipulation have become versatile toolkits for manufacturing NPs in a highly controlled manner with low batch-to-batch variability. In this review, we present the fundamentals of microfluidic fabrication strategies, including mixing-, droplet-, and multiple field-based microfluidic methods. We highlight the formation of functional NPs using these microfluidic reactors, with an emphasis on lipid NPs, polymer NPs, lipid-polymer hybrid NPs, supramolecular NPs, metal and metal-oxide NPs, metal–organic framework NPs, covalent organic framework NPs, quantum dots, perovskite nanocrystals, biomimetic NPs, etc. we discuss future directions in microfluidic fabrication for accelerated development of functional NPs, such as device parallelization for large-scale NP production, highly efficient optimization of NP formulations, and AI-guided design of multi-step microfluidic reactors. [ABSTRACT FROM AUTHOR]

Abstract: Heat-treatment was used to precipitate PbS quantum dots (QDs) in silicate glasses doped with different amounts of Ag2O, and the influence of Ag2O on QDs was investigated. Under given heat-treatment conditions, the absorption coefficients and photoluminescence intensities of PbS QDs increased with the addition of Ag2O. Ag clusters formed by thermal treatment nucleated formation of PbS QDs in glasses. [Copyright &y& Elsevier]

Abstract: CdSe quantum dots (QDs) were precipitated in silicate glasses under various durations and temperatures of heat-treatment. Absorption and photoluminescence (PL) spectra of the QDs showed the quantum confinement effect from CdSe QDs. When the glass was heat-treated for 10h, estimated average QD sizes increased from 5.2nm when the glass was heat-treated at 490°C and to 6.9nm when it was treated at 500°C. When the glass was heat-treated at 480°C, estimated average QD sizes were 4.9nm after 20h and 5.3nm after 30h. The PL peak position was independent of the excitation wavelengths; this result indicates that the size distribution of CdSe QDs was narrow. [ABSTRACT FROM AUTHOR]

Abstract: PbSe quantum dots (QDs) were synthesized in borosilicate glass and their optical properties were investigated. The typical quantum confinement effects were clearly observed from the absorption when the average radii of the QDs changed from 1.7 to 3.1nm. Photoluminescence from PbSe QDs was achieved in 1.1–2.2μm wavelength region that covers the entire fiber-optic telecommunication window. Borosilicate glasses containing controlled size of PbSe QDs provide potentials for the fiber-optic amplifiers. [Copyright &y& Elsevier]

The authors report the modulation of photoluminescence intensity from lead sulfide quantum dots using two laser beams with different wavelengths. Photoluminescence from lead sulfide quantum dots in glasses was reversibly switched between the “bright” and “dark” states and degree of darkening to 16% of the initial intensity was realized. Changes in the photoluminescence were insensitive to temperature but strongly dependent on the power densities of the modulating laser beam. This efficient optical modulation has potential for optical switching and memory device applications. [ABSTRACT FROM AUTHOR]

The authors report that the darkening and brightening of photoluminescence from PbS quantum dots can be controlled by adjusting the temperature and excitation intensity. Intensity of the photoluminescence from PbS quantum dots increased with time (photobrightening) when temperature was below 150 K. On the other hand, darkening was observed at temperatures above 150 K. It was also possible to make a reversible change between photobrightening and photodarkening from the same specimen through the careful control of the temperature and excitation intensity. [ABSTRACT FROM AUTHOR]

The formation mechanism of Cd–S–Se quantum dots (QDs) with a CdS/CdSe core–shell structure within a silicate glass system was investigated by monitoring the change in the first excitonic absorption peak of CdSe, CdS, and Cd–S–Se QDs as a function of the heat‐treatment (HT) duration. When a silicate glass containing QD formation components for CdSe or CdS single‐phased QDs was heat‐treated, CdSe QDs grew via Ostwald ripening, whereas CdS QDs hardly formed within the given silicate glass matrix. When the glass, including CdO, ZnSe, and ZnS, was utilized for the synthesis of Cd–S–Se QDs within the glass matrix, Cd–S–Se QDs were successfully formed and exhibited similar growth behavior to CdSe QDs during the initial stage of HT. The structural changes in the QD‐embedded glasses during HT were also monitored by Raman spectroscopy and discussed, and a possible formation mechanism of CdSe/CdS core–shell‐structured QDs within silicate glasses is suggested. [ABSTRACT FROM AUTHOR]

An electrochemiluminescence (ECL) based method is described for the determination of the activity of the enzyme uracil-DNA glycosylase (UDG). It is based on the use of nicking enzyme-assisted signal amplification and catalytic hairpin assembly. UDG can recognize and hydrolyze the uracil bases from the stem of hairpin DNA1 (HP1). This causes the opening of HP1 to form a straight strand DNA. The straight HP1 can hybridize with hairpin DNA2 (HP2) to form a DNA duplex. In the presence of nicking enzyme, it can recognize and cut the specific sequences in the HP2 of the DNA duplex, and a subsequent release of HP1. It hybridizes with other HP2 to trigger the continuous cleavage of HP2, concomitantly generating abundant intermediate sequences (S1). The hairpin DNA3 (HP3) is immobilized on a gold electrode via Au-S chemistry. In the presence of S1, HP3 hybridizes with S1 and its hairpin structure is opened. This hybridization causes displacement from hairpin DNA4 (HP4), and S1 is released to initiate the next hybridization process. Thus, a massive number of HP3-HP4 duplexes is generated after the cyclic process. Subsequently, the cDNA modified on bio-bar-coded AuNP-CdSe quantum dots are immobilized on the electrode by hybridization with the redundant part of the opened HP4. This results in a significant amplification of the ECL signal. This biosensor is sensitive and selective for UDG. The detection limit is 6 mU·mL−1 and the dynamic range extends from 0.02 to 22 U·mL−1. The method was applied to real samples and gained good performance, thereby providing an ideal way for DNA repair enzyme-related biomedical research and diagnosis.Schematic presentation of the electrochemiluminescence (ECL) detection of uracil-DNA glycosylase (UDG) based on nicking enzyme assisted signal amplification and catalyzed hairpin assembly. The bio-barcoded Au NP-CdSe QDs serve as the ECL signal probes to achieve a significantly signal amplification. [ABSTRACT FROM AUTHOR]

The nanocomposites prepared by the combination of SiO 2 and carbon quantum dots (CQDs) have the advantages of low toxicity, high fluorescence intensity, high biocompatibility and good water solubility, which greatly broaden its application range. Nevertheless, if only SiO 2 and CQDs are simply combined without any structural design, the stability of the nanocomposites will be poor, which will affect its practical application value. In this work, we first synthesized ordered mesoporous silica (OMS) rapidly in aqueous solution by a facile method (30 min), and then generated CQDs in situ in the mesoporous channels of OMS by hydrothermal method to obtain CQDs@OMS fluorescent nanocomposites. The chemical structure and morphology of OMS and CQDs@OMS were characterized by FT-IR, XRD, SAXRD and TEM, indicating that CQDs was successfully encapsulated in OMS. The stability test results of CQDs@OMS indicate that CQDs can be stably present in the mesoporous channels of OMS, and the fluorescence intensity of CQDs@OMS nanocomposites is almost independent of ionic strength, pH and storage time. The optical performance results show that the optimal excitation wavelength of CQDs@OMS nanocomposites is about 340 nm, the emission wavelength is about 440 nm. Using CQDs@OMS nanocomposites as fluorescent probes to detect Fe3+, it was found that CQDs@OMS responded very quickly to Fe3+. The fluorescence quenching intensity of CQDs@OMS has a good linear relationship with the concentration of Fe3+ in the range of 25–750 μM. Therefore, the trace amount of Fe3+ in solution can be calculated by measuring the relative magnitude of fluorescence intensity. [ABSTRACT FROM AUTHOR]

Well‐defined density functional theory (DFT) calculations are performed as the first exploratory study for the atomic and electronic mechanism of defect mediated morphology and optical properties of CdnSen (n = 3, 10, 13, and 33) quantum dots (QDs) in inorganic amorphous matrix. The intrinsic defects of pristine CdSe QDs, and the interfacial defects between the QDs and surrounding amorphous matrix, were systematically studied. The calculated electronic structure suggested that the pristine CdSe QDs capped by the structural modifiers or non‐bridging oxygen in the amorphous matrix gave rise to the structure reconstruction and paired defect states at the edge of the valence and conduction bands. The orbital analysis elucidated that the redistribution of the majority of HOMO and LUMO electron density was localized over the bonds formed by capping atoms and QDs. These changes in the electronic structures were further demonstrated by CdSe QDs embedded sodium silicate glasses. It turned out that Se atoms at QDs/glass interface were much more active than those found on the surface of organically passivated CdSe QDs. The results serve as a new paradigm in materials research to explore structural origins of defect emission from QDs and a new strategy to develop glasses containing QDs with high photoluminescence quantum efficiency. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL) properties of PbSe and Sr2+‐doped PbSe quantum dots (QDs) doped in silicate glasses were investigated by changing the excited laser wavelength and intensity. When BaO was replaced by SrO, the Sr2+‐doped PbSe QDs formed and showed large blue‐shifts in both absorption and PL bands compared to the PbSe QDs. It is attributed to the increasing in band gap resulted by the incorporation of Sr2+ ions into PbSe QDs. These two kinds of QDs were excited by the laser with the wavelengths of 1319 and 1532 nm. When rising the pumping intensity up to 1000 mW, the PL intensity from Sr2+‐doped PbSe QDs monotonically increased, while, the PL intensity from PbSe QDs reached maximum at pumping intensity at ~200 mW (λex = 1319 nm) and ~300 mW (λex = 1532 nm). The good resistance to photodarkening of Sr2+‐doped PbSe QDs is indicated passivation effect on the surface defects from Sr2+ ions doping. For Sr2+‐doped PbSe QDs the anti‐Stokes photoluminescence (ASPL) were observed when using both 1319 and 1532 nm excitation. The integrated intensity of the ASPL is linear with the excitation intensity, which indicates that the ASPL belongs to the phonon‐assisted one‐photon process. And the ASPL intensity as a function of excitation intensity shows a size dependence of the QDs. [ABSTRACT FROM AUTHOR]

• Adjusting optical performance of PbS QDs embedded glass to cover the whole telecommunication bands. • Revealing the absorption cross sections of PbS QDs at 1040 nm are 4–13 × 10−16 cm2, the bi- and tri-excitons lifetime is ∼60 and ∼10 ps. • Obtaining the broadband net gain in 1500–1620 nm in single PbS QDs embedded glass with a threshold of < N >=4.1. • Achieving a maximum gain time of ∼20 ps and gain coefficient of >120 cm−1 for PbS QDs embedded glass. Lead sulfide quantum dots (PbS QDs) have a unique performance in the near-infrared (NIR) range. In-situ precipitation of PbS QDs in glass not only improves the stability, but also is easy to be fabricated fiber compatible with silicon photonics. In this work, we reveal that absorption cross sections of PbS QDs at 1040 nm are 4–13 × 10−16 cm2, the bi- and tri-excitons lifetime are∼60 and ∼10 ps due to the trap-assisted Auger recombination using transient absorption (TA). Furthermore, we demonstrate the broadband net gain in 1500–1600 nm in single PbS QDs embedded glass with a gain threshold of < N >= 4.1 (averaged number of excitons), and achieve the maximum gain time of ∼20 ps and gain coefficient of >120 cm−1. These results illustrate the existing obstacles to achieve the net gain in PbS QDs embedded glass, which is important for applications on fiber amplifiers, NIR laser and high-capacity telecommunication. [ABSTRACT FROM AUTHOR]

PbSe quantum dots (QDs) were precipitated in borosilicate glasses, and effects of B 2 O 3 content on the optical properties of glasses were investigated. The diameters of the PbSe QDs in glasses increased from 3.70 nm to 7.32 nm as [B 2 O 3 ] increased from 10 mol% to 20 mol% even when all glasses were heat-treated at 460 °C for 10 h. Photoluminescence (PL) peaks extended to wavelengths of 2154 nm when B 2 O 3 content increased to 20 mol%. The viscosities η of glasses at 460 °C decreased significantly with the addition of B 2 O 3 i.e., 2.86 × 10 13 Pa·s at [B 2 O 3 ] = 0.0% to 1.94 × 10 11 Pa·s at [B 2 O 3 ] = 20%. These decreases in η led to a large increase in the diffusion of ions in glass matrix including Pb 2 + and Se 2 − that facilitated the precipitation and growth of PbSe QDs in glasses. These results demonstrate that the wavelength of PL emissions by QDs can be controlled by manipulating the composition of the host glass. [ABSTRACT FROM AUTHOR]

CsPbBr3−xIx quantum dots were precipitated in boro‐germanate glasses with various Br/I ratios by the melt‐quenching method. When the heat treatment temperature (TH) increased from 480 to 550°C, more I− entered the perovskite crystal lattice, resulting in lattice expansion, the X‐ray diffraction peaks of CsPbBr1.5I1.5 glasses shifted to small angles. The high concentration of I− entered into the perovskite crystal lattice, decreasing the bandgap. The photoluminescence (PL) peaks of CsPbBr1.5I1.5 glasses redshifted from 577 to 620 nm, the PL peaks of CsPbBrI2 glasses shifted from 614 to 636 nm, and the PL peaks of CsPbBr0.5I2.5 glasses shifted from 650 to 672 nm. As the ratio of Br/I reduced from 2.5/0.5 to 0.5/2.5, the PL lifetime of CsPbBr3−xIx glass increased from 2.08 to 74.5 ns. With the delay time from 1 to 1500 ps, the carriers gradually accumulated in the band‐edge state, and the bleaching signal intensity increased. Then more and more carriers returned to the ground state through radiative or nonradiative recombination, the bleaching signal intensity decreased. [ABSTRACT FROM AUTHOR]

[Display omitted] • Poly(PCDA)/ZnO QDs composites were synthesized by the solution-mixing method, and the optimum formulation was obtained. • Poly(PCDA)/ZnO QDs composites have both the thermochromic properties of PDA and the superior fluorescent properties of ZnO QDs. Poly(PCDA)/ZnO QDs composites were applied to film materials and inks, and the corresponding films and inks also possessed dual properties of thermochromism and fluorescence, which proved that the composites had good application properties. Composites of polydiacetylenes (PDA) and zinc oxide (ZnO) find diverse applications in thermochromic inks, colorimetric sensors, and anticounterfeiting, albeit often with complex preparation methods, single functionality, and high color-changing temperature ranges. This study presents environmentally friendly aqueous composites exhibiting dual thermochromic and fluorescent properties, achieved by integrating ZnO quantum dots (QDs) with particle sizes below 10 nm with PDA. By varying the concentration ratio of ZnO QDs to PDA, the effects on fluorescence and thermochromic properties were systematically explored. The interaction between ZnO QDs and PDA interfaces causes alterations to the energy states in the conjugated π-orbital array within PDA molecules. In contrast to pure PDA solutions, the composite materials not only exhibit thermochromism but also fluorescence. Demonstratively, the composite was applied as functional ink or paste for writing, film production, and inkjet printing, maintaining robust thermochromic sensitivity and fluorescence properties in the resulting specimens. This methodology imparts excellent multifunctionality to composite materials, enhancing and broadening their application potential. [ABSTRACT FROM AUTHOR]

Lead selenide quantum dots (QDs) were precipitated in germanosilicate glasses to investigate the effect of GeO 2 content on the precipitation and optical properties. The absorption and photoluminescence (PL) bands red-shifted strongly as GeO 2 concentration increased. After heat-treatment at 470 °C for 10 h, the first excitonic absorption bands red-shifted from 801 nm to 2593 nm as GeO 2 content increased from 0 to 40 mol%, and thus PL at 2619 nm was achieved. The corresponding average QD diameters were 2.48–12.54 nm. The precipitation of large PbSe QDs resulted from the enhancement of diffusion with the increase of GeO 2 concentration, and is the main reason for these red-shifts. [ABSTRACT FROM AUTHOR]

• A facile in-situ synthesis of chalcogenide CdS quantum dots in phosphate glass is presented and its growth was performed by the heat treatment process. • An intense visible luminescence centered at 550 nm is observed owing to the growth of CdS quantum dots with an average size of 8.10 nm into a phosphate glass. • The emission intensity significatively decreases as a function of the heat treatment time and a Stokes shift is observed for the S2 sample compared with the original sample, indicating the growth of CdS quantum dots. • The color tunability observed from the CIE chromaticity diagram denotes the facile synthesis of luminescent CdS QDs in a novel and stable glass system. CdS quantum dots (QDs) are a promising nanomaterial for optical and emitter devices. The main difficulty is controlling the QDs growth due to their instability and tendency to agglomerate. Phosphate glasses are an interesting host for QDs owing to their intrinsic characteristics. In this sense, we report an in-situ synthesis of luminescent CdS QDs into a phosphate glass and their growth upon heat treatments (HT) above Tg for different times. Quasi-spherical QDs were obtained with the average size of 8.1 nm and an intense emission at 550 nm under excitation at 340 nm. A significant emission intensity decreases and about 10 nm Stokes shift was observed after HT. Hence, this study describes a facile synthesis of luminescent CdS QDs in a novel and stable glass system, which makes it a promising material for photonic applications with possibility to adjust the emitted light wavelength. [Display omitted] [ABSTRACT FROM AUTHOR]

A facile synthetic approach to prepare environmentally friendly white fluorescent carbon dots (CDs)/ZnO quantum dots (QDs) composites through electrostatic force is described. This method can be used for fabrication of high-performance white light-emitting diodes (WLEDs). The fluorescence emission spectra of WLED devices covered a range from 425 nm to 750 nm. WLEDs had a CIE chromaticity coordinate of (0.30, 0.34) and a color temperature of 7093 K. [ABSTRACT FROM AUTHOR]

In this work, PbSe QDs were precipitated in oxyfluoride glass-ceramics containing BaF2 nanocrystals. Tunable and broad absorption and photoluminescence from PbSe QDs doped glass-ceramics were observed in the near-infrared wavelength range. When the glasses were heat-treated at temperatures below 560°C using one-step heat-treatment schedule, single photoluminescence band was observed from each sample. Upon high temperature (560°C or 570°C) one-step or two-step heat-treatment, dual-band photoluminescence was observed. These two photoluminescence bands in each spectrum were separated by a gap of ~110–150meV, and as a result, effective full width at half maximum as large as ~500nm was recorded. [ABSTRACT FROM AUTHOR]

Despite the advancement of plasma membrane imaging techniques, there is an unmet need for fluorescent probes which can "light up" the lipid bilayer with an extended time scale. In this work, a novel fluorescent probe is developed for imaging of plasma membrane. The probe comprises a cellulose nanocrystal (CNC) scaffold derived from low-cost wood pulp, carbon dots (CDs) fluorophore that is in-situ synthesized on the surface of CNC, and cholesterol (Chol) ligand with aminated polyethylene glycol (PEG) spacer. In the CNC-CDs@PEG-Chol configuration, the Chol ligand provides excellent binding affinity onto plasma membrane due to its hydrophobic nature, while CDs contribute to the marvelous optical stability, as well as the high quantum yield of the fluorescent probe. For CNC scaffold, their unique morphological property allows the assembling of dense Chol ligands, and more importantly, impedes the diffusions of imaging moieties into the cytoplasm. Therefore, the fluorescent probe is featured with remarkable specificity and satisfying plasma membrane imaging time window, which covers the co-incubation time from 30 to 90 min. In contrast, the mono-dispersed CDs@PEG-Chol probe can be facilely internalized by the cells at a co-incubation time as short as 20 min. CNC is proven to be responsible for the different imaging time scales by providing the confinement effects. The proposed fluorescent probe is believed to be a promising tool for studying the plasma membrane behaviors associated with cellular physiological processes. [Display omitted] • A cellulose nanocrystal based probe for cell membrane imaging is proposed. • The probe is constructed by in-situ carbon dots synthesis and cholesterol grafting. • High plasma membrane binding affinity is resulted from dense cholesterol. • Cellular internalization of probe is inhibited by cellulose nanocrystal. • Long-time fluorescent imaging of plasma membrane is achieved. [ABSTRACT FROM AUTHOR]

Embedding CdTe QDs into glass can improve the thermal and chemical stability of QDs, which facilitates their wide and endurable applications. However, the small tunable spectral range of photoluminescence, low quantum efficiency, and large full width at half maximum limit their wide applications. In this work, effect of introduction of CaO into glass matrix on the formation and optical properties of CdTe QDs is investigated. High concentration of CaO in glasses increases the solubility of Te in glasses, and consequently hinders the precipitation of CdTe QDs in glasses. By adjusting the heat-treatment temperature, average diameters of CdTe QDs are tuned in the range of 2.5–9.0 nm and their photoluminescence bands are tuned from 550 to 800 nm. More importantly, the absolute photoluminescence quantum yield is boosted up to 41.9 %. Results reported in this work indicate that CdTe quantum dots embedded in glasses are promising for applications in light-emitting devices. • High CaO concentration promote the dissolution of Te in the glass. • Photoluminescence of CdTe QDs doped glass is tuned from 550 nm to 800 nm. • PLQY of CdTe QDs doped glasses reaches 41.9 %. [ABSTRACT FROM AUTHOR]

Using dendritic mesoporous silica nanoparticles (DMSNs) for quantum dots (QDs) enrichment and signal amplification is an emerging strategy for improving the detection sensitivity of lateral flow immunoassay (LFIA). In this study, a new and convenient approach is developed to prepare water‐dispersible DMSNs‐QDs. A series of DMSNs with various diameters (138, 251, 368, and 471 nm) are studied for loading QDs and LFIA applications. The resultant water‐dispersible DMSNs‐QDs exhibit a high fluorescence retention of 81.8%. The increase in particle size from 138 to 471 nm results in an increase in loading capacity of QDs and a decrease in binding quantity of the DMSNs‐QDs in the test line of LFIA. This trade‐off leads to an optimal DMSNs‐QDs size of 368 nm with a limit of detection reaching 10 pg mL−1 (equivalent to 9.0 × 10−14m) for the detection of C‐reactive protein, which is nearly an order of magnitude more sensitive than the literature. To the best of the authors' knowledge, this study is the first to demonstrate the distinctive role of DMSN's size for QDs enrichment and LFIA. The strategy developed from this work is useful for the rational design of high‐quality QDs‐based nanoparticles for ultrasensitive detection. [ABSTRACT FROM AUTHOR]

Abstract: The size and spatial distribution of PbS QDs in glasses need to be controlled in order to achieve desired optical characteristics. This paper reports on the use of several rare-earth oxides such as Ho2O3, Er2O3, and La2O3 to control the size of PbS QDs in silicate glasses. Additions of rare-earth oxides result in blue shifts of the absorption bands from 1344nm to 930nm, and the wavelengths of PL bands can be controlled between 1421nm and 1035nm. Additions of up to 0.8mol% of Ho2O3 decreased the diameters of PbS QDs from 4.82nm to 3.02nm. The same tendencies were found for both Er2O3 and La2O3 additions, although the size of PbS QDs increased as the ionic radius of rare-earth ions increased. It is proposed that clusters of RE–O bonds act as nucleating agents for the precipitation of PbS QDs. [Copyright &y& Elsevier]

Lead selenide quantum dots (QDs) were precipitated in lithium-aluminum-silicate glass-ceramics. Their optical properties and the crystallization behavior of both glass host and PbSe QDs were investigated. When the glasses heat-treated at 480–520 °C for 10 h, the absorption bands from PbSe QDs were tuned from 1051 to 2016 nm, and the PL bands from 1165 to 2095 nm. Upon the dwelling time 10 h, the crystallization of glass host required relatively higher heating temperature (∼490 °C) than the formation of PbSe QDs (∼480 °C). With the heat treatment at 490 °C for10 h, the PLQY from PbSe QDs in glass-ceramics reached ∼38.7 %. Phase separation induced the glass crystallization and had a significant effect on the distribution of PbSe QDs. To study the growth kinetics of PbSe QDs, the glasses were heat treated at 480 °C and 500 °C for various durations. The average diameters of PbSe QDs (D) showed exponential relationship to the growth time (t), described by the equation D(t)∼ t x. In rapid growth stage, the growth exponents x is ∼ 0.56 at 480 °C and ∼ 0.47 at 500 °C, and then decrease to ∼ 0.13 and ∼ 0.10, respectively. The formation of a large number of LiAlO 2 crystals in glass hindered the diffusion of semiconductor ions, which is the main reason for the decreasing in the growth rate of PbSe QDs. [ABSTRACT FROM AUTHOR]

Cellular labelling is possible to offer significant information after transplantation for the purpose of determining stem cell therapy's efficacy. According to the research, it has been reported that graphene oxide quantum dots (GOQDs) are a kind of healthy biological labelling agent for stem cells which show little cytotoxicity. GOQDs' interactions have been examined on the dental pulp stem cells (hDPSCs) of human beings for the purpose of investigating GOQD's biocompatibility and uptake and explored GOQDs' effects on hDPSCs' metabolic activity and the proliferation. According to the outcomes, GDQDs have been accepted by hDPSCs in a time-dependent and concentration-dependent behaviour. Moreover, no important changes have been discovered within hDOPSCs' proliferation, viability as well as metabolic activity after treatment with GOQDs. Therefore, such resources have shown that GOQDs can be multifunctional agents for cell therapy, drug delivery as well as cell imaging and also as outstanding candidates for labelling stem cells. [ABSTRACT FROM AUTHOR]

An elaborated organic–inorganic hybrid method to fabricate functional textiles with excellent bacterial killing efficiencies (>99.99% against a broad spectrum of bacteria) and bacterial monitoring (differential fluorescence recovery upon contacting pathogens) is reported. Such functional textiles are extremely promising in medical and healthcare scenarios, particularly for healthcare professionals to avoid cross-contamination and post-infection caused by the continually used textiles. [Display omitted] • Excellent bactericidal efficiencies of >99.99% towards both E. coli and S. aureus. • Bacterial monitoring via differential FL recovery ability after exposure to pathogens. • Address the exclusive cross-infection concerns raised by disposable textiles. • Development of safe, comfortable, and intelligent textiles for medical healthcare. In medical, healthcare, and packaging industries, antibacterial textiles are widely used. However, contamination of textiles with bacteria can result in exclusive cross-infection. To address this issue, we devised an engineering strategy for creating organic–inorganic hybrid layers on the surface of fiber materials by combining MXene quantum dots (MQDs) with highly efficient antimicrobial agents, endowing the textiles with dual functions of bacterial killing and monitoring. Surface-functionalized MQDs were anchored on the surface of cellulose nonwovens (CNWs) by hydrogen bonding (MQDs@CNWs), followed by immobilization of Ni2+ ions by metal affinity coordination (Ni@MQDs@CNWs). In the last step, the antimicrobial compounds with catechol moieties were coordinated with Ni2+ to produce the modified textile named as NCA@Ni@MQDs@CNWs. Fluorescence (FL) recovery experiments demonstrated that NCA@Ni@MQDs@CNWs had differential FL recovery ability after exposure to pathogens with different concentrations indicating its ability for bacteria monitoring. Moreover, NCA@Ni@MQDs@CNWs exhibited excellent bactericidal efficiencies of >99.99% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in a 30-min. This work presents a novel approach for design and fabrication of biocidal textiles with ability of sensing bacteria. [ABSTRACT FROM AUTHOR]

[Display omitted] • Obtaining the CdSe QDs with diameters of 2–10 nm in glass. • Achieving the PL changed from dual band to narrow band covering 500–700 nm. • Revealing the relationship between surface defect types and defect emission. • Exploring the effects of Cd2+ and Se2- related surface defect on PL properties. Cadmium selenide quantum dots (CdSe QDs) have shown great potential for applications in the visible range over the last few decades. Embedding CdSe QDs into inorganic glass matrix improves their stability, but complicates their surface conditions and deteriorates their optical properties. In this work, CdSe QDs with tunable and narrow band intrinsic photoluminescence (PL) are precipitated in silicate glasses by adjusting the heat-treatment temperatures. With the increase in heat-treatment temperature, PL peaks shift to long wavelength side with simultaneous reduction in full width at half maximum, while both PL quantum yields and lifetimes decrease. Ultrafast carrier dynamics analysis reveals that the above changes on PL properties are induced by the transformation of Cd2+-related to Se2--related surface defects during heat-treatment. Electron trapping by shallow Cd2+-related defects is responsible for the broad band defect emission, and hole trapping by Se2--related defects results in quenching of defect emission. These results uncover the relationship between surface defects of CdSe QDs and their PL properties, facilitating their applications towards light-emitting diodes (LEDs), backlight displays, and lasers. [ABSTRACT FROM AUTHOR]

Lead chalcogenide quantum dots have particular optoelectronic properties induced by the quantum confinement effects and have promising potentials towards applications in infrared spectral range. Modulation of the optoelectronic properties of lead chalcogenide quantum dots is mainly based on the thermal treatment. In this work, precipitation and optical properties of alloyed PbSe x S 1-x quantum dots in glasses are investigated. Composition, size, absorption, and photoluminescence properties of PbSe x S 1-x quantum dots are modulated by chalcogen elements in glasses and thermal treatment. By adjusting the concentration of ZnSe and ZnS in the glasses, average diameters of the PbSe x S 1-x quantum dots are tuned in the range of 8.1–16.1 nm, their absorption peak wavelengths are tuned in the range of 724–2497 nm, and photoluminescence bands are tuned in the range of 1016–2165 nm with full width at half maximum in the range of 167–517 nm. Fraction of Se in the PbSe x S 1-x quantum dots precipitated in glasses is dependent on the concentrations of ZnSe and ZnS in the glass and heat-treatment temperature. Increase in concentration of S in the glasses results in the reduction of relative fraction of Se in the PbSe x S 1-x quantum dots formed in glasses. More importantly, high heat-treatment temperature promotes the enrichment of Se in PbSe x S 1-x quantum dots, and Se fraction in PbSe x S 1-x quantum dots increases from 0.69 to 0.89, from 0.53 to 0.85, from 0.47 to 0.79, and from 0.45 to 0.76 for those precipitated in glasses with ZnSe/(ZnSe+ZnS) molar ratios of 0.545, 0.375, 0.286, and 0.231, respectively. Increase in ZnSe/(ZnSe+ZnS) molar ratios in glasses also leads to reduction in diameter of PbSe x S 1-x quantum dots formed in glasses. These alloyed PbSe x S 1-x quantum dots also exhibit improved photoluminescence quantum yields and enhanced resistance to thermal quenching of photoluminescence. [Display omitted] [ABSTRACT FROM AUTHOR]

Gd3+-doped quantum dots (QDs) have been widely used as small-sized bifunctional contrast agents for fluorescence/magnetic resonance (FL/MR) dual-modality imaging. However, Gd3+ doping will always compromise the FL of host QDs. Therefore, balancing the Gd3+ doping and the optical properties of QDs is crucial for constructing high-performance bifunctional nanoprobes. Additionally, most paramagnetic QDs are synthesized in the organic phase and need to be transferred to the aqueous phase for bioimaging. Herein, ingeniously designed shell-doped Cu-In-S/ZnS:Gd3+ QDs have been prepared in the aqueous phase. It has been demonstrated that isolating paramagnetic Gd3+ from fluorescent Cu-In-S core via doping Gd3+ into ZnS shell not only avoided the decrease of FL quantum yield (QY), but also ensured the water accessibility of paramagnetic Gd3+ ions, by which the FL QY and r 1 relaxivity of Cu-In-S/ZnS:Gd3+ QDs achieved as much as 15.6% and 15.33 mM-1·s-1, respectively. These high-performance QDs with excellent stability, low biotoxicity, and good tumor permeability were successfully applied for in vivo tumor FL/MR dual-modality imaging, and have shown significant potential in the precision detection and diagnosis of diseases. [Display omitted] • The effects of Gd3+-doped region on the properties of core/shell QDs are investigated. • Isolating Gd3+ from fluorescent Cu-In-S core via doping Gd3+ into ZnS shell. • A facile aqueous synthesis of fluorescent and paramagnetic bifunctional QDs is proposed. • The hydrodynamic diameter of shell-doped Cu-In-S/ZnS:Gd3+ QDs is very small. [ABSTRACT FROM AUTHOR]