InP quantum dots(QDs)have been a major building block of modern display technology due to their high photoluminescence quantum yield(PLQY)in the visible spectrum,superior stability,and eco-friendly composition.However...InP quantum dots(QDs)have been a major building block of modern display technology due to their high photoluminescence quantum yield(PLQY)in the visible spectrum,superior stability,and eco-friendly composition.However,their applications at short-wave infrared(SWIR)have been hindered by their low efficiency.Here,we report the synthesis of efficient and SWIR-emitting InP QDs by precisely controlling the InP core nucleation using a low-cost ammonia phosphorus precursor,while avoiding size-limiting ZnCl_(2) for effective copper doping.Subsequent epitaxial growth of a lattice-matched ZnSe/ZnS multishell enhanced the QD sphericity and surface smoothness and yielded a record PLQY of 66% with an emission peak at 960 nm.When QDs were integrated as the high-refractive-index luminescent core of a liquid waveguide-based luminescent solar concentrator(LSC),the device achieved an optical efficiency of 7.36%.This performance arises from their high PLQY,spectral alignment with the responsivity peak of silicon solar cells,and the optimized core/cladding waveguide structure.These results highlight the potential of InP QDs as a promising nanomaterial for SWIR emission and applications.展开更多
As an essential candidate for environment-friendly luminescent quantum dots(QDs),CuInS-based QDs have attracted more attention in recent years.However,several drawbacks still hamper their industrial applications,such ...As an essential candidate for environment-friendly luminescent quantum dots(QDs),CuInS-based QDs have attracted more attention in recent years.However,several drawbacks still hamper their industrial applications,such as lower photoluminescence quantum yield(PLQY),complex synthetic pathways,uncontrollable emission spectra,and insufficient photostability.In this study,CuInZnS@ZnS core/shell QDs was prepared via a one-pot/three-step synthetic scheme with accurate and tunable control of PL spectra.Then their ensemble spectroscopic properties during nucleation formation,alloying,and ZnS shell growth processes were systematically investigated.PL peaks of these QDs can be precisely manipulated from 530 to 850 nm by controlling the stoichiometric ratio of Cu/In,Zn^(2+)doping and ZnS shell growth.In particular,CuInZnS@ZnS QDs possess a significantly long emission lifetime(up to 750 ns),high PLQY(up to 85%),and excellent crystallinity.Their spectroscopic evolution is well validated by Cu-deficient related intragap emission model.By controlling the stoichiometric ratio of Cu/In,two distinct Cu-deficient related emission pathways are established based on the differing oxidation states of Cu defects.Therefore,this work provides deeper insights for fabricating high luminescent ternary or quaternary-alloyed QDs.展开更多
Classical computation of electronic properties in large-scale materials remains challenging.Quantum computation has the potential to offer advantages in memory footprint and computational scaling.However,general and v...Classical computation of electronic properties in large-scale materials remains challenging.Quantum computation has the potential to offer advantages in memory footprint and computational scaling.However,general and viable quantum algorithms for simulating large-scale materials are still limited.We propose and implement random-state quantum algorithms to calculate electronic-structure properties of real materials.Using a random state circuit on a small number of qubits,we employ real-time evolution with first-order Trotter decomposition and Hadamard test to obtain electronic density of states,and we develop a modified quantum phase estimation algorithm to calculate real-space local density of states via direct quantum measurements.Furthermore,we validate these algorithms by numerically computing the density of states and spatial distributions of electronic states in graphene,twisted bilayer graphene quasicrystals,and fractal lattices,covering system sizes from hundreds to thousands of atoms.Our results manifest that the random-state quantum algorithms provide a general and qubit-efficient route to scalable simulations of electronic properties in large-scale periodic and aperiodic materials.展开更多
The development of quantum materials for single-photon emission is crucial for the advancement of quantum information technology.Although significant advancements have been witnessed in recent years for single-photon ...The development of quantum materials for single-photon emission is crucial for the advancement of quantum information technology.Although significant advancements have been witnessed in recent years for single-photon sources in the near-infrared band(λ∼700–1000 nm),several challenges have yet to be addressed for ideal single-photon emission at the telecommunication band.In this study,we present a droplet-epitaxy strategy for O-band to C-band single-photon source-based semiconductor quantum dots(QDs)using metal-organic vaporphase epitaxy(MOVPE).By investigating the growth conditions of the epitaxial process,we have successfully synthesized InAs/InP QDs with narrow emission lines spanning a broad spectral range of λ∼1200–1600 nm.The morphological and optical properties of the samples were characterized using atomic force microscopy and microphotoluminescence spectroscopy.The recorded single-photon purity of a plain QD structure reaches g^((2))(0)=0.16,with a radiative recombination lifetime as short as 1.5 ns.This work provides a crucial platform for future research on integrated microcavity enhancement techniques and coupled QDs with other quantum photonics in the telecom bands,offering significant prospects for quantum network applications.展开更多
The hybridization gap in strained-layer InAs/In_(x)Ga_(1−x) Sb quantum spin Hall insulators(QSHIs)is significantly enhanced compared to binary InAs/GaSb QSHI structures,where the typical indium composition,x,ranges be...The hybridization gap in strained-layer InAs/In_(x)Ga_(1−x) Sb quantum spin Hall insulators(QSHIs)is significantly enhanced compared to binary InAs/GaSb QSHI structures,where the typical indium composition,x,ranges between 0.2 and 0.4.This enhancement prompts a critical question:to what extent can quantum wells(QWs)be strained while still preserving the fundamental QSHI phase?In this study,we demonstrate the controlled molecular beam epitaxial growth of highly strained-layer QWs with an indium composition of x=0.5.These structures possess a substantial compressive strain within the In_(0.5)Ga_(0.5)Sb QW.Detailed crystal structure analyses confirm the exceptional quality of the resulting epitaxial films,indicating coherent lattice structures and the absence of visible dislocations.Transport measurements further reveal that the QSHI phase in InAs/In_(0.5)Ga_(0.5)Sb QWs is robust and protected by time-reversal symmetry.Notably,the edge states in these systems exhibit giant magnetoresistance when subjected to a modest perpendicular magnetic field.This behavior is in agreement with the𝑍2 topological property predicted by the Bernevig–Hughes–Zhang model,confirming the preservation of topologically protected edge transport in the presence of enhanced bulk strain.展开更多
To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.T...To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.This source is based on spontaneous four-wave mixing(SFWM)in a piece of shallow-ridge silicon waveguide.Theoretical analysis shows that the waveguide dispersion could be tailored by adjusting the ridge width,enabling broadband photon pair generation by SFWM across C band and O band.The spontaneous Raman scattering(SpRS)in silicon waveguides is also investigated experimentally.It shows that there are two regions in the spectrum of generated photons from SpRS,which could be used to achieve cross-band photon pair generation.A chip of shallow-ridge silicon waveguide samples with different ridge widths has been fabricated,through which cross-band photon pair generation is demonstrated experimentally.The experimental results show that the source can be achieved using dispersion-optimized shallow-ridge silicon waveguides.This cross-band quantum light source provides a way to develop new fiber-based quantum communication functions utilizing both C band and O band and extends applications of quantum networks.展开更多
The intra- and inter-band relaxation dynamics of CdSe/CdS/ZnS core/shell/shell quantum dots are investigated with the aid of time-resolved nonlinear transmission spectra which are obtained using femtosecond pump-probe...The intra- and inter-band relaxation dynamics of CdSe/CdS/ZnS core/shell/shell quantum dots are investigated with the aid of time-resolved nonlinear transmission spectra which are obtained using femtosecond pump-probe technique. By selectively exciting the core and shell carrier, the dynamics are studied in detail. Carrier relaxation is found faster in the conduction band of the CdS shell （about 130 fs） than that in the conduction band of the CdSe core （about 400 fs）. From the experiments it is distinctly demonstrated the existence of the defect states in the interface between the CdSe core and the CdS shell, indicating that ultrafast spectroscopy might be a suitable tool in studying interface and surface morphology properties in nanosystems.展开更多
Peroxymonosulfate(PMS)activation in heterogeneous processes is a promising water treatment technology.Nevertheless,the high energy consumption and low efficiency during the reaction are ineluctable,due to electron cyc...Peroxymonosulfate(PMS)activation in heterogeneous processes is a promising water treatment technology.Nevertheless,the high energy consumption and low efficiency during the reaction are ineluctable,due to electron cycling rate limitation.Herein,a new strategy is proposed based on a quantum dots(QDs)/PMS system.Co-ZnS QDs are synthesized by a water phase coprecipitation method.The inequivalent lattice-doping of Co for Zn leads to the generation of surface sulfur vacancies(SVs),which modulates the surface of the catalyst to form an electronic nonequilibrium surface.Astonishingly,the plasticizer micropollutants can be completely degraded within only tens of seconds in the Co-Zn S QDs/PMS system due to this type of surface modulation.The interfacial reaction mechanism is revealed that pollutants tend to be adsorbed on the cobalt metal sites as the electron donors,where the internal electrons of pollutants are captured by the metal species and transferred to the surface SVs.Meanwhile,PMS adsorbed on the SVs is reduced to radicals by capturing electrons,achieving effective electron recovery.Dissolved oxygen(DO)molecules are also easily attracted to catalyst defects and are reduced to O_(2)^(·-),further promoting the degradation of pollutants.展开更多
Over the past few decades,I-III-VI quantum dots(QDs)have attracted considerable attention due to their large Stokes shifts,good eco-friendliness,and wide tunable emissions.In this work,a facile microwave-assisted aque...Over the past few decades,I-III-VI quantum dots(QDs)have attracted considerable attention due to their large Stokes shifts,good eco-friendliness,and wide tunable emissions.In this work,a facile microwave-assisted aqueous route using glutathione(GSH)and citric acid(CA)as dual stabilizers is introduced to synthesize AgInGaS/ZnS(AIGS/ZnS)core/shell QDs.An exceptional photoluminescence quantum yield(PL QY)as high as 79%is successfully achieved,boosting the best performance of water-dispersible AIGS QDs.By varying the Ag/Ga ratio,the PL peak wavelength can be tuned from 547 to 616 nm,and luminescent hydrogel films with different colors are obtained by embedding AIGS/ZnS QDs in polyacrylamide/poly-vinyl alcohol(PAAm/PVA)hydrogels.The white light-emitting diode(WLED)with a high color rendering index(CRI)of 92.1(R_(9)=92.0)and a correlated color temperature(CCT)of 3022 K is fabricated using QDs-PAAm/PVA hydrogel films in combination with a blue InGaN LED chip,indicating that the as-prepared QDs are competitive color-conversion materials for WLEDs.展开更多
The potassium-ion batteries(PIBs)have become the promising energy storage devices due to their relatively moderate cost and plenteous potassium resources.Whereas,the main drawback of PIBs is unsatisfacto ry electroche...The potassium-ion batteries(PIBs)have become the promising energy storage devices due to their relatively moderate cost and plenteous potassium resources.Whereas,the main drawback of PIBs is unsatisfacto ry electrochemical perfo rmance induced by the larger ionic radius of potassium ion.Herein,we report a well-designed,uniform-dispersed,and morphology-controllable zinc sulfide(ZnS)quantum dots loading on graphene as an anode in the PIBs.The directed uniform dispersion of the in-situ growing ZnS quantum dots(~2.8 nm in size)on graphene can mitigate the volume effect during the insertionextraction process and shorten the migration path of potassium ions.As a result,the battery exhibits superior cycling stability(350.4 mAh/g over 200 cycles at 0.1 A/g)and rate performance(98.8 mAh/g at2.0 A/g).We believe the design of active material with quantum dot-minimized size provides a novel route into PIBs and contributes to eliminating the major electrode failure issues of the system.展开更多
Size-dependence of optical properties and energy relaxation in CdSe/ZnS quantum dots （QDs） were investigated by two-colour femtosecond （fs） pump-probe （400/800 nm） and picosecond time-resolved photoluminescence ...Size-dependence of optical properties and energy relaxation in CdSe/ZnS quantum dots （QDs） were investigated by two-colour femtosecond （fs） pump-probe （400/800 nm） and picosecond time-resolved photoluminescence （ps TRPL） experiments. Pump-probe measurement results show that there are two components for the excited carriers relaxation, the fast one with a time constant of several ps arises from the Auger-type recombination, which shows almost particle sizeindependence. The slow relaxation component with a time constant of several decades of ns can be clearly determined with ps TRPL spectroscopy in which the slow relaxation process shows strong particle size-dependence. The decay time constants increase from 21 to 34 ns with the decrease of particle size from 3.2 to 2.1 nm. The room-temperature decay lifetime is due to the thermal mixing of bright and dark excitons, and the size-dependence of slow relaxation process can be explained very well in terms of simple three-level model.展开更多
Quantum dots （QD） nanoparticles have been widely used in biomedical and electronics fields, because of their novel optical properties. Consequently it confers enormous potential for human exposure and environmental ...Quantum dots （QD） nanoparticles have been widely used in biomedical and electronics fields, because of their novel optical properties. Consequently it confers enormous potential for human exposure and environmental release. To increase the biocompatibility of QDs, a variety of surface coatings or functional groups are added to increase their bioactivity and water solubility. Human adult low calcium high temperature （HaCaT） cells are the epithelial cells derived from adult human skin that exhibits normal differentiation capacity and a DNA fingerprint pattern that is unaffected by long-term cultivation, transformation, or the presence of multiple chromosomal alternations. Human keratinocytes, HaCaT cells were used to systematically evaluate the cytotoxicity of biocompatible QD made of CdSe metal core and ZnS shell with three different coatings and at three different wavelengths （530, 580 and 620 nm）. In terms of half- maximal inhibitory concentration, QSA-QDs with amine-polyethyleneglycol coating and QSH-QDs with amphiphilic polymer coating were not cytotoxic, while QEI-QDs with polyethylenimine coating were highly toxic to the HaCaT cells in comparison to a reference CulnS2/ZnS. QEI-QDs led to significant increase in reactive oxygen species, decrease in mitochondrial membrane potential and DNA damage in HaCaT cells. The mechanisms of toxicity of QEI-530 and QEI-580 can be attributed to the combination of intracellular reactive oxygen species production and loss of MMP. The QDs toxicity can be attributed to the polyethylemimine surface coating which was highly toxic to cells in comparison with amine-polyethyleneglycol, but not due to the release of cadmium ions.展开更多
In the present work,a solution-based co-precipitation method has been adopted to synthesize pure and cobalt-doped ZnS quantum dots and characterized by XRD,SEM,TEM with EDX,FTIR and gas sensing properties.XRD analysis...In the present work,a solution-based co-precipitation method has been adopted to synthesize pure and cobalt-doped ZnS quantum dots and characterized by XRD,SEM,TEM with EDX,FTIR and gas sensing properties.XRD analysis has shown a single phase of ZnS quantum dots having a zinc blend structure.TEM and XRD line broadening indicated that the average crystallite size in the sample is in the range of 2 to 5 nm.SEM micrographs show spherical-shaped quantum dots.FTIR studies show that cobalt has been successfully doped into the ZnS cubic lattice.EDX spectra have analyzed the elemental presence in the samples and it is evident that the spectra confirmed the presence of cobalt(Co),zinc(Zn),oxygen(O),and sulphur(S)elements only and no other impurities are observed.The ZnS-based quantum dot sensors reveal high sensitivity towards 50 ppm of ammonia vapors at an operating temperature of 70℃.Hence,ZnS-based quantum dots can be a promising and quick traceable sensor towards ammonia sensing applications with good response and recovery time.展开更多
A novel bovine serum albumin （BSA） imprinted Mn-doped ZnS quantum dots （Mn：ZnS QDs） is firstly reported. The molecular imprinted polymer （MIP） functionalized Mn：ZnS QDs （Mn：ZnS @SiO2@MIP） include the prepar...A novel bovine serum albumin （BSA） imprinted Mn-doped ZnS quantum dots （Mn：ZnS QDs） is firstly reported. The molecular imprinted polymer （MIP） functionalized Mn：ZnS QDs （Mn：ZnS @SiO2@MIP） include the preparation of Mn：ZnS QDs, the coating of silica on the surface of Mn：ZnS QDs, and the functional polymerization by sol-gel reaction using 3-aminophenylboronic acid as the functional and cross-linking monomer in the presence of BSA （Mn：ZnS@SiO2@MIP-BSA）, and then the elution of the imprinted BSA on the surface of Mn：ZnS@SiO2 QDs. The results showed that the phosphorescence of Mn：ZnS@SiO2@MIP is stronger quenched by BSA than that of non-imprinted one （Mn：ZnS@SiO2@NIP）, indicating that the selectivity of the imprinted Mn：ZnS quantum dots toward BSA is superior to that of non-imprinted one.展开更多
A novel chemiluminescence（CL） performance of CdTe/CdS/ZnS quantum dots（QDs） with periodate（KIO_4） was studied.Effects of concentration and pH on the CL system were investigated.Electron spin resonance（ESR） and...A novel chemiluminescence（CL） performance of CdTe/CdS/ZnS quantum dots（QDs） with periodate（KIO_4） was studied.Effects of concentration and pH on the CL system were investigated.Electron spin resonance（ESR） and the effects of radical scavenger analysis were employed for identification of intermediate species.The CL spectra for this system showed only one maximum emission peak centered around 620 nm,which was similar with photoluminescence（PL） spectra of CdTe/CdS/ZnS QDs.The CL of CdTe/CdS/ZnS QDs was induced by direct chemical oxidation and the possible mechanism could be explained by radiative recombination of injected holes and electrons.This investigation not only provided new sight into the optical characteristics of CdTe/CdS/ZnS QDs,but also broadened their potential optical utilizations.展开更多
Tb3＋-doped ZnSe and ZnSe/ZnS nanocrystals were synthesized using modified hot-injection method. The observation of the characteristic quantum dots absorption features in a time-gated excitation spectrum was recorded ...Tb3＋-doped ZnSe and ZnSe/ZnS nanocrystals were synthesized using modified hot-injection method. The observation of the characteristic quantum dots absorption features in a time-gated excitation spectrum was recorded while monitoring Tb3＋ emission at 545 nm provided direct evidence for successful incorporation of dopant ions into semiconductor host. Relatively long decay time （-1.5 ms） of Tb3＋ emission indicated that dopant ions were well protected from interaction with surface ligands. Emission properties of core ZnSe：Tb3＋ nanocrystals were only slightly modified upon growth of ZnS shell.展开更多
The poor film formation of Cd Se/Zn S quantum dots(QDs) during spin-coating makes a substantial impact on the device performance of quantum dot light-emitting diodes(QLEDs). This work proposes a method to improve the ...The poor film formation of Cd Se/Zn S quantum dots(QDs) during spin-coating makes a substantial impact on the device performance of quantum dot light-emitting diodes(QLEDs). This work proposes a method to improve the morphology of the quantum dot light-emitting layer(EML) by adding small organic molecular 4,4'-Bis(9 H-carbazol-9-yl) biphenyl(CBP) into the layer. Its surface roughness reduces from 6.21 nm to 2.71 nm, which guarantees a good contact between hole transport layer(HTL) and EML. Consequently, the Cd Se/Zn S QDs:CBP based QLED achieves maximum external quantum efficiency(EQE) of 5.86%, and maximum brightness of 10 363 cd/m^(2). It is demonstrated that the additive of small organic molecules could be an effective way to improve the brightness and the efficiency of QLEDs.展开更多
文摘InP quantum dots(QDs)have been a major building block of modern display technology due to their high photoluminescence quantum yield(PLQY)in the visible spectrum,superior stability,and eco-friendly composition.However,their applications at short-wave infrared(SWIR)have been hindered by their low efficiency.Here,we report the synthesis of efficient and SWIR-emitting InP QDs by precisely controlling the InP core nucleation using a low-cost ammonia phosphorus precursor,while avoiding size-limiting ZnCl_(2) for effective copper doping.Subsequent epitaxial growth of a lattice-matched ZnSe/ZnS multishell enhanced the QD sphericity and surface smoothness and yielded a record PLQY of 66% with an emission peak at 960 nm.When QDs were integrated as the high-refractive-index luminescent core of a liquid waveguide-based luminescent solar concentrator(LSC),the device achieved an optical efficiency of 7.36%.This performance arises from their high PLQY,spectral alignment with the responsivity peak of silicon solar cells,and the optimized core/cladding waveguide structure.These results highlight the potential of InP QDs as a promising nanomaterial for SWIR emission and applications.
基金Fund Project for Transformation of Scientific and Technological Achievements of Jiangsu Province of China(BA2023020)。
文摘As an essential candidate for environment-friendly luminescent quantum dots(QDs),CuInS-based QDs have attracted more attention in recent years.However,several drawbacks still hamper their industrial applications,such as lower photoluminescence quantum yield(PLQY),complex synthetic pathways,uncontrollable emission spectra,and insufficient photostability.In this study,CuInZnS@ZnS core/shell QDs was prepared via a one-pot/three-step synthetic scheme with accurate and tunable control of PL spectra.Then their ensemble spectroscopic properties during nucleation formation,alloying,and ZnS shell growth processes were systematically investigated.PL peaks of these QDs can be precisely manipulated from 530 to 850 nm by controlling the stoichiometric ratio of Cu/In,Zn^(2+)doping and ZnS shell growth.In particular,CuInZnS@ZnS QDs possess a significantly long emission lifetime(up to 750 ns),high PLQY(up to 85%),and excellent crystallinity.Their spectroscopic evolution is well validated by Cu-deficient related intragap emission model.By controlling the stoichiometric ratio of Cu/In,two distinct Cu-deficient related emission pathways are established based on the differing oxidation states of Cu defects.Therefore,this work provides deeper insights for fabricating high luminescent ternary or quaternary-alloyed QDs.
基金supported by the Major Project for the Integration of ScienceEducation and Industry (Grant No.2025ZDZX02)。
文摘Classical computation of electronic properties in large-scale materials remains challenging.Quantum computation has the potential to offer advantages in memory footprint and computational scaling.However,general and viable quantum algorithms for simulating large-scale materials are still limited.We propose and implement random-state quantum algorithms to calculate electronic-structure properties of real materials.Using a random state circuit on a small number of qubits,we employ real-time evolution with first-order Trotter decomposition and Hadamard test to obtain electronic density of states,and we develop a modified quantum phase estimation algorithm to calculate real-space local density of states via direct quantum measurements.Furthermore,we validate these algorithms by numerically computing the density of states and spatial distributions of electronic states in graphene,twisted bilayer graphene quasicrystals,and fractal lattices,covering system sizes from hundreds to thousands of atoms.Our results manifest that the random-state quantum algorithms provide a general and qubit-efficient route to scalable simulations of electronic properties in large-scale periodic and aperiodic materials.
基金supported by the National Natural Science Foundation of China (Grant Nos.12494604,12393834,12393831,62274014,6223501662335015)the National Key R&D Program of China (Grant No.2024YFA1208900)。
文摘The development of quantum materials for single-photon emission is crucial for the advancement of quantum information technology.Although significant advancements have been witnessed in recent years for single-photon sources in the near-infrared band(λ∼700–1000 nm),several challenges have yet to be addressed for ideal single-photon emission at the telecommunication band.In this study,we present a droplet-epitaxy strategy for O-band to C-band single-photon source-based semiconductor quantum dots(QDs)using metal-organic vaporphase epitaxy(MOVPE).By investigating the growth conditions of the epitaxial process,we have successfully synthesized InAs/InP QDs with narrow emission lines spanning a broad spectral range of λ∼1200–1600 nm.The morphological and optical properties of the samples were characterized using atomic force microscopy and microphotoluminescence spectroscopy.The recorded single-photon purity of a plain QD structure reaches g^((2))(0)=0.16,with a radiative recombination lifetime as short as 1.5 ns.This work provides a crucial platform for future research on integrated microcavity enhancement techniques and coupled QDs with other quantum photonics in the telecom bands,offering significant prospects for quantum network applications.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (Grant Nos.XDB28000000 and XDB0460000)the Quantum Science and Technology-National Science and Technology Major Project (Grant No.2021ZD0302600)the National Key Research and Development Program of China(Grant No.2024YFA1409002)。
文摘The hybridization gap in strained-layer InAs/In_(x)Ga_(1−x) Sb quantum spin Hall insulators(QSHIs)is significantly enhanced compared to binary InAs/GaSb QSHI structures,where the typical indium composition,x,ranges between 0.2 and 0.4.This enhancement prompts a critical question:to what extent can quantum wells(QWs)be strained while still preserving the fundamental QSHI phase?In this study,we demonstrate the controlled molecular beam epitaxial growth of highly strained-layer QWs with an indium composition of x=0.5.These structures possess a substantial compressive strain within the In_(0.5)Ga_(0.5)Sb QW.Detailed crystal structure analyses confirm the exceptional quality of the resulting epitaxial films,indicating coherent lattice structures and the absence of visible dislocations.Transport measurements further reveal that the QSHI phase in InAs/In_(0.5)Ga_(0.5)Sb QWs is robust and protected by time-reversal symmetry.Notably,the edge states in these systems exhibit giant magnetoresistance when subjected to a modest perpendicular magnetic field.This behavior is in agreement with the𝑍2 topological property predicted by the Bernevig–Hughes–Zhang model,confirming the preservation of topologically protected edge transport in the presence of enhanced bulk strain.
基金supported by the Quantum Science and Technology-National Science and Technology Major Project (Grant No.2024ZD0302502 for WZ)the National Natural Science Foundation of China(Grant No.92365210 for WZ)+1 种基金Tsinghua Initiative Scientific Research Program (for WZ)the project of Tsinghua University-Zhuhai Huafa Industrial Share Company Joint Institute for Architecture Optoelectronic Technologies (JIAOT,for YH)。
文摘To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.This source is based on spontaneous four-wave mixing(SFWM)in a piece of shallow-ridge silicon waveguide.Theoretical analysis shows that the waveguide dispersion could be tailored by adjusting the ridge width,enabling broadband photon pair generation by SFWM across C band and O band.The spontaneous Raman scattering(SpRS)in silicon waveguides is also investigated experimentally.It shows that there are two regions in the spectrum of generated photons from SpRS,which could be used to achieve cross-band photon pair generation.A chip of shallow-ridge silicon waveguide samples with different ridge widths has been fabricated,through which cross-band photon pair generation is demonstrated experimentally.The experimental results show that the source can be achieved using dispersion-optimized shallow-ridge silicon waveguides.This cross-band quantum light source provides a way to develop new fiber-based quantum communication functions utilizing both C band and O band and extends applications of quantum networks.
基金This work was supported by the National Natural Science Foundation of China （No.11074003） and the Key Program of Educational Commission of Anhui Province of China （No.KJ2010AI32）. For the help of Prof. J. L. Zhao at Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences in sample preparation is greatly appreciated.
文摘The intra- and inter-band relaxation dynamics of CdSe/CdS/ZnS core/shell/shell quantum dots are investigated with the aid of time-resolved nonlinear transmission spectra which are obtained using femtosecond pump-probe technique. By selectively exciting the core and shell carrier, the dynamics are studied in detail. Carrier relaxation is found faster in the conduction band of the CdS shell （about 130 fs） than that in the conduction band of the CdSe core （about 400 fs）. From the experiments it is distinctly demonstrated the existence of the defect states in the interface between the CdSe core and the CdS shell, indicating that ultrafast spectroscopy might be a suitable tool in studying interface and surface morphology properties in nanosystems.
基金financially supported by the National Natural Science Foundation of China(Nos.52070046,52122009,51808140and 51838005)the Introduced of Innovative R&D Team Project under the“Pearl River Talent Recruitment Program”of Guangdong Province(No.2019ZT08L387)+1 种基金the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(Young Scholar)the support from the BL14W1beamline of Shanghai Synchrotron Radiation Facility(SSRF,China)。
文摘Peroxymonosulfate(PMS)activation in heterogeneous processes is a promising water treatment technology.Nevertheless,the high energy consumption and low efficiency during the reaction are ineluctable,due to electron cycling rate limitation.Herein,a new strategy is proposed based on a quantum dots(QDs)/PMS system.Co-ZnS QDs are synthesized by a water phase coprecipitation method.The inequivalent lattice-doping of Co for Zn leads to the generation of surface sulfur vacancies(SVs),which modulates the surface of the catalyst to form an electronic nonequilibrium surface.Astonishingly,the plasticizer micropollutants can be completely degraded within only tens of seconds in the Co-Zn S QDs/PMS system due to this type of surface modulation.The interfacial reaction mechanism is revealed that pollutants tend to be adsorbed on the cobalt metal sites as the electron donors,where the internal electrons of pollutants are captured by the metal species and transferred to the surface SVs.Meanwhile,PMS adsorbed on the SVs is reduced to radicals by capturing electrons,achieving effective electron recovery.Dissolved oxygen(DO)molecules are also easily attracted to catalyst defects and are reduced to O_(2)^(·-),further promoting the degradation of pollutants.
基金supported by the National Natural Science Foundation of China(NSFC,No.62074044,NSFC,No.61904036),Zhongshan-Fudan Joint Innovation Center,Jihua Laboratory Projects of Guangdong Province(X190111UZ190)Shanghai Post-doctoral Excellence Program(2021016)Shanghai Rising-Star program(22YF1402000).
文摘Over the past few decades,I-III-VI quantum dots(QDs)have attracted considerable attention due to their large Stokes shifts,good eco-friendliness,and wide tunable emissions.In this work,a facile microwave-assisted aqueous route using glutathione(GSH)and citric acid(CA)as dual stabilizers is introduced to synthesize AgInGaS/ZnS(AIGS/ZnS)core/shell QDs.An exceptional photoluminescence quantum yield(PL QY)as high as 79%is successfully achieved,boosting the best performance of water-dispersible AIGS QDs.By varying the Ag/Ga ratio,the PL peak wavelength can be tuned from 547 to 616 nm,and luminescent hydrogel films with different colors are obtained by embedding AIGS/ZnS QDs in polyacrylamide/poly-vinyl alcohol(PAAm/PVA)hydrogels.The white light-emitting diode(WLED)with a high color rendering index(CRI)of 92.1(R_(9)=92.0)and a correlated color temperature(CCT)of 3022 K is fabricated using QDs-PAAm/PVA hydrogel films in combination with a blue InGaN LED chip,indicating that the as-prepared QDs are competitive color-conversion materials for WLEDs.
基金financial support of this work by the Science,Technology,and Innovation Commission of Shenzhen Municipality(Nos.JCYJ20180508151856806 and JCYJ20180306171121424)the Key R&D Program of Shanxi(No.2019ZDLGY04-05)+3 种基金the National Natural Science Foundation of Shaanxi(Nos.2019JLZ-01,2019JLM-29 and 2020JQ-189)the National Natural Science Foundation of China(No.21603175)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(Nos.2019-TS-06 and 2020-BJ-03)China Postdoctoral Science Foundation(No.2018M641015)。
文摘The potassium-ion batteries(PIBs)have become the promising energy storage devices due to their relatively moderate cost and plenteous potassium resources.Whereas,the main drawback of PIBs is unsatisfacto ry electrochemical perfo rmance induced by the larger ionic radius of potassium ion.Herein,we report a well-designed,uniform-dispersed,and morphology-controllable zinc sulfide(ZnS)quantum dots loading on graphene as an anode in the PIBs.The directed uniform dispersion of the in-situ growing ZnS quantum dots(~2.8 nm in size)on graphene can mitigate the volume effect during the insertionextraction process and shorten the migration path of potassium ions.As a result,the battery exhibits superior cycling stability(350.4 mAh/g over 200 cycles at 0.1 A/g)and rate performance(98.8 mAh/g at2.0 A/g).We believe the design of active material with quantum dot-minimized size provides a novel route into PIBs and contributes to eliminating the major electrode failure issues of the system.
基金Project supported by the National Natural Science Foundation of China (Grant No 10774099)Science and Technology Commission of Shanghai Municipal (Grant No 06PJ14042)+1 种基金Shanghai Municipal Education Commission (Grant No 06AZ089)the Shanghai Leading Academic Discipline Program (T0104)
文摘Size-dependence of optical properties and energy relaxation in CdSe/ZnS quantum dots （QDs） were investigated by two-colour femtosecond （fs） pump-probe （400/800 nm） and picosecond time-resolved photoluminescence （ps TRPL） experiments. Pump-probe measurement results show that there are two components for the excited carriers relaxation, the fast one with a time constant of several ps arises from the Auger-type recombination, which shows almost particle sizeindependence. The slow relaxation component with a time constant of several decades of ns can be clearly determined with ps TRPL spectroscopy in which the slow relaxation process shows strong particle size-dependence. The decay time constants increase from 21 to 34 ns with the decrease of particle size from 3.2 to 2.1 nm. The room-temperature decay lifetime is due to the thermal mixing of bright and dark excitons, and the size-dependence of slow relaxation process can be explained very well in terms of simple three-level model.
基金supported by NSF-SBIR grant #IIP-0823040 and NSF-CREST program with grant #HRD-0833178
文摘Quantum dots （QD） nanoparticles have been widely used in biomedical and electronics fields, because of their novel optical properties. Consequently it confers enormous potential for human exposure and environmental release. To increase the biocompatibility of QDs, a variety of surface coatings or functional groups are added to increase their bioactivity and water solubility. Human adult low calcium high temperature （HaCaT） cells are the epithelial cells derived from adult human skin that exhibits normal differentiation capacity and a DNA fingerprint pattern that is unaffected by long-term cultivation, transformation, or the presence of multiple chromosomal alternations. Human keratinocytes, HaCaT cells were used to systematically evaluate the cytotoxicity of biocompatible QD made of CdSe metal core and ZnS shell with three different coatings and at three different wavelengths （530, 580 and 620 nm）. In terms of half- maximal inhibitory concentration, QSA-QDs with amine-polyethyleneglycol coating and QSH-QDs with amphiphilic polymer coating were not cytotoxic, while QEI-QDs with polyethylenimine coating were highly toxic to the HaCaT cells in comparison to a reference CulnS2/ZnS. QEI-QDs led to significant increase in reactive oxygen species, decrease in mitochondrial membrane potential and DNA damage in HaCaT cells. The mechanisms of toxicity of QEI-530 and QEI-580 can be attributed to the combination of intracellular reactive oxygen species production and loss of MMP. The QDs toxicity can be attributed to the polyethylemimine surface coating which was highly toxic to cells in comparison with amine-polyethyleneglycol, but not due to the release of cadmium ions.
文摘In the present work,a solution-based co-precipitation method has been adopted to synthesize pure and cobalt-doped ZnS quantum dots and characterized by XRD,SEM,TEM with EDX,FTIR and gas sensing properties.XRD analysis has shown a single phase of ZnS quantum dots having a zinc blend structure.TEM and XRD line broadening indicated that the average crystallite size in the sample is in the range of 2 to 5 nm.SEM micrographs show spherical-shaped quantum dots.FTIR studies show that cobalt has been successfully doped into the ZnS cubic lattice.EDX spectra have analyzed the elemental presence in the samples and it is evident that the spectra confirmed the presence of cobalt(Co),zinc(Zn),oxygen(O),and sulphur(S)elements only and no other impurities are observed.The ZnS-based quantum dot sensors reveal high sensitivity towards 50 ppm of ammonia vapors at an operating temperature of 70℃.Hence,ZnS-based quantum dots can be a promising and quick traceable sensor towards ammonia sensing applications with good response and recovery time.
基金financial support from the Hubei Science Foundation(No.2010CDA061)
文摘A novel bovine serum albumin （BSA） imprinted Mn-doped ZnS quantum dots （Mn：ZnS QDs） is firstly reported. The molecular imprinted polymer （MIP） functionalized Mn：ZnS QDs （Mn：ZnS @SiO2@MIP） include the preparation of Mn：ZnS QDs, the coating of silica on the surface of Mn：ZnS QDs, and the functional polymerization by sol-gel reaction using 3-aminophenylboronic acid as the functional and cross-linking monomer in the presence of BSA （Mn：ZnS@SiO2@MIP-BSA）, and then the elution of the imprinted BSA on the surface of Mn：ZnS@SiO2 QDs. The results showed that the phosphorescence of Mn：ZnS@SiO2@MIP is stronger quenched by BSA than that of non-imprinted one （Mn：ZnS@SiO2@NIP）, indicating that the selectivity of the imprinted Mn：ZnS quantum dots toward BSA is superior to that of non-imprinted one.
基金supported by the National Natural Science Foundation of China(Nos.81373373,21435002,21227006)
文摘A novel chemiluminescence（CL） performance of CdTe/CdS/ZnS quantum dots（QDs） with periodate（KIO_4） was studied.Effects of concentration and pH on the CL system were investigated.Electron spin resonance（ESR） and the effects of radical scavenger analysis were employed for identification of intermediate species.The CL spectra for this system showed only one maximum emission peak centered around 620 nm,which was similar with photoluminescence（PL） spectra of CdTe/CdS/ZnS QDs.The CL of CdTe/CdS/ZnS QDs was induced by direct chemical oxidation and the possible mechanism could be explained by radiative recombination of injected holes and electrons.This investigation not only provided new sight into the optical characteristics of CdTe/CdS/ZnS QDs,but also broadened their potential optical utilizations.
基金Project supported by Wroclaw Research Centre EIT+within the project"The Application of Nanotechnology in Advanced Materials”-Nano Mat(POIG.01.01.02-02-002/08) co-financed by the European Regional Development Fund(Operational Programme Innovative Economy,1.1.2)
文摘Tb3＋-doped ZnSe and ZnSe/ZnS nanocrystals were synthesized using modified hot-injection method. The observation of the characteristic quantum dots absorption features in a time-gated excitation spectrum was recorded while monitoring Tb3＋ emission at 545 nm provided direct evidence for successful incorporation of dopant ions into semiconductor host. Relatively long decay time （-1.5 ms） of Tb3＋ emission indicated that dopant ions were well protected from interaction with surface ligands. Emission properties of core ZnSe：Tb3＋ nanocrystals were only slightly modified upon growth of ZnS shell.
基金supported by the Fundamental Research Funds for the Central Universities of China (No.JD2019JGPY0020)the National Natural Science Foundation of China (No.51573036)the Industry-University-Research Cooperation Project of Aviation Industry Corporation of China (No.CXY2013HFGD20)。
文摘The poor film formation of Cd Se/Zn S quantum dots(QDs) during spin-coating makes a substantial impact on the device performance of quantum dot light-emitting diodes(QLEDs). This work proposes a method to improve the morphology of the quantum dot light-emitting layer(EML) by adding small organic molecular 4,4'-Bis(9 H-carbazol-9-yl) biphenyl(CBP) into the layer. Its surface roughness reduces from 6.21 nm to 2.71 nm, which guarantees a good contact between hole transport layer(HTL) and EML. Consequently, the Cd Se/Zn S QDs:CBP based QLED achieves maximum external quantum efficiency(EQE) of 5.86%, and maximum brightness of 10 363 cd/m^(2). It is demonstrated that the additive of small organic molecules could be an effective way to improve the brightness and the efficiency of QLEDs.
