Ratiometric fluorescent detection of iron(Ⅲ)(Fe^(3+))offers inherent self-calibration and contactless analytic capabilities.However,realizing a dual-emission near-infrared(NIR)nanosensor with a low limit of detection...Ratiometric fluorescent detection of iron(Ⅲ)(Fe^(3+))offers inherent self-calibration and contactless analytic capabilities.However,realizing a dual-emission near-infrared(NIR)nanosensor with a low limit of detection(LOD)is rather challenging.In this work,we report the synthesis of water-dispersible erbium-hyperdoped silicon quantum dots(Si QDs:Er),which emit NIR light at the wavelengths of 810 and 1540 nm.A dual-emission NIR nanosensor based on water-dispersible Si QDs:Er enables ratiometric Fe^(3+)detection with a very low LOD(0.06μM).The effects of pH,recyclability,and the interplay between static and dynamic quenching mechanisms for Fe^(3+)detection have been systematically studied.In addition,we demonstrate that the nanosensor may be used to construct a sequential logic circuit with memory functions.展开更多
The emission of silicon quantum dots is weak when their surface is passivated well. Oxygen or nitrogen on the surface of silicon quantum dots can break the passivation to form localized electronic states in the band g...The emission of silicon quantum dots is weak when their surface is passivated well. Oxygen or nitrogen on the surface of silicon quantum dots can break the passivation to form localized electronic states in the band gap to generate active centers where stronger emission occurs. From this point of view, we can build up radiative matter for emission. Emissions of various wavelengths can be obtained by controlling the surface bonds of silicon quantum dots. Our experimental results demonstrate that annealing is important in the treatment of the activation, and stimulated emissions at about 600 and 700 nm take place on active silicon quantum dots.展开更多
A series of boron- and phosphorus-doped silicon wafers are used to prepare a series of doped silicon nanocrystals （nc-Si） by high-energy ball milling with carboxylic acid-terminated surface. The sizes of the nc-Si s...A series of boron- and phosphorus-doped silicon wafers are used to prepare a series of doped silicon nanocrystals （nc-Si） by high-energy ball milling with carboxylic acid-terminated surface. The sizes of the nc-Si samples are demonstrated to be 〈 S nm. The doping levels of the nc-Si are found to be nonlinearly dependent on the original doping level of the wafers by x-ray photoelectron spectroscopy measurement. It is found that the nonlinear doping process will lead to the nonlinear chemical passivation and photoluminescence （I3L） intensity evolution. The doping, chemical passivation and PL mechanisms of the doped nc-Si samples prepared by mechanochemical synthesis are analyzed in detail.展开更多
Imaging-guided cancer therapy provides a simultaneous tumor imaging and treatment, which helps to eliminate the excessive toxicity to the healthy tissues. For this purpose, multifunctional probes capable of both imagi...Imaging-guided cancer therapy provides a simultaneous tumor imaging and treatment, which helps to eliminate the excessive toxicity to the healthy tissues. For this purpose, multifunctional probes capable of both imaging and curing are needed. In this work, we synthesize water-soluble silicon quantum dots（Si QDs） smaller than 5 nm. Such Si QDs are used for delivering the hydrophobic drug phthalocyanine（Pc）. The as-prepared Si/Pc nanocomposite particles show efficient transmembrane delivery into cells and feasible biocompatibility. Moreover, these composite particles emit dualchannel fluorescence signals even after cellular internalization and demonstrate robust photostability in the Si channel.More interestingly, the Si/Pc composite particles show efficient photodynamic therapy effects against tumors both in vitro and in vivo.展开更多
Fluorescent silicon quantum dots(Si QDs)were hydrothermally synthesized from a mixture of 3(2-aminoethylamino)propyl(dimethoxymethylsilane)(AEAPDMMS)and poly(vinylpyrrolidine)(PVP).The resulting Si QDs exhibited good ...Fluorescent silicon quantum dots(Si QDs)were hydrothermally synthesized from a mixture of 3(2-aminoethylamino)propyl(dimethoxymethylsilane)(AEAPDMMS)and poly(vinylpyrrolidine)(PVP).The resulting Si QDs exhibited good water solubility and high stability.Under the optimized conditions,the probe revealed an excellent linear fluorescence quenching effect on Co2+ranging from 1μmol/L to 120μmol/L with a limit of detection of 0.37μmol/L(based on 3 s/k).The quenching mechanism was studied,showing that static quenching(SQE)causes the main effect.Furthermore,the test paper based on Si QDs was prepared,which is cost-effective,high sensitivity,good selectivity,easy to use and show excellent anti-interference capability.This method was applied to analyze the content of Co2+in environmental water samples with satisfying results.展开更多
Silicon quantum dots(SiQDs)with high water-soluble and favorable photostability were prepared by a one-step hydrothermal method.The average diameter of SiQDs was 2.02 nm characterized by transmission electron microsco...Silicon quantum dots(SiQDs)with high water-soluble and favorable photostability were prepared by a one-step hydrothermal method.The average diameter of SiQDs was 2.02 nm characterized by transmission electron microscope.It was to be noted that the as-prepared SiQDs showed eff ective antibacterial activity,which was attributed to electrostatic interaction and the generation of reactive oxygen species.The minimum inhibitory concentration of SiQDs against Escherichia coli and Staphylococcus aureus was 0.45 mg/mL and 0.38 mg/mL,respectively.Besides,based on the static quenching eff ect-induced fluorescence quenching mechanism,the SiQDs exhibited high sensitivity and selectivity for detecting tetracyclines(TC).A good linear relationship was obtained between the fluorescence intensity of SiQDs and the concentration of tetracycline(TC)in the range of 0–0.08μmol/L(R^(2)=0.9993)with a detection limit of 0.0176μmol/L.Furthermore,the TC content in the honey samples was determined using the SiQDs.All the results suggest that the as-prepared SiQDs can be a potential fluorescent probe for application in antibacterial and analysis.展开更多
In this paper,silicon quantum dots(SiQDs)with green fluorescence are synthesized by solvothermal reaction of 3-(2,3-epoxypropoxy)propyltrimethoxysilane(GPTMS)and ethylenediaminetetraacetic acid(EDTA),and then SiQDs ar...In this paper,silicon quantum dots(SiQDs)with green fluorescence are synthesized by solvothermal reaction of 3-(2,3-epoxypropoxy)propyltrimethoxysilane(GPTMS)and ethylenediaminetetraacetic acid(EDTA),and then SiQDs are bonded to the surface of silica to obtain a new nano-on-micro stationary phase(SiO_(2)-SiQDs)for reversed-phase chromatography.The successful preparation of SiO_(2)-SiQDs stationary phase is demonstrated by a variety of characterizations,such as transmission electron microscopy,laser confocal microscopy,elemental analysis and Fourier infrared spectroscopy.In addition,the chromatographic performance of the prepared stationary phase is evaluated and it shows good separation performance for non-polar substances such as alkylbenzene,aniline and polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography.It is also verified that the stationary phase has good methyl selectivity and shape selectivity.More interestingly,the separation of prednisolone and hydrocortisone isomers can also be achieved at a low ratio of organic solvents,indicating that this new stationary phase has a good application prospect in isomer separation.展开更多
In this work,the fundamental mechanism of ultrabright fluorescence from surface-modified colloidal silicon quantum dots is investigated in depth using ultrafast spectroscopy.The underlying energy band structure corres...In this work,the fundamental mechanism of ultrabright fluorescence from surface-modified colloidal silicon quantum dots is investigated in depth using ultrafast spectroscopy.The underlying energy band structure corresponding to such highly efficient direct bandgap-like emissions in our surface-modified silicon quantum dots is unraveled by analyzing the transient optical spectrum,which demonstrates the significant effect of surface molecular engineering.It is observed that special surface modification,which creates novel surface states,is responsible for the different emission wavelengths and the significant improvement in the photoluminescence quantum yields.Following this essential understanding,surface-modified silicon quantum dots with deep blue to orange emission are successfully prepared without changing their sizes.展开更多
Nowadays the development of Internet of Things （loT） and defense technologies imperatively needs high-performance photodetectors that can work in a broadband wavelength range, in particular, covering the mid-infrar...Nowadays the development of Internet of Things （loT） and defense technologies imperatively needs high-performance photodetectors that can work in a broadband wavelength range, in particular, covering the mid-infrared （MIR） region [1]. This generates great interest in the incorporation of a series of novel optoelectronic materials and structures into the photodetectors. Graphene and colloidal quantum dots （QDs） are key players among novel materials used to fabricate high-performance photodetectors [2-4]. By taking advantage of the high mobility of graphene and excellent tunable optical absorption of colloidal QDs,展开更多
There are many disadvantages such as small detection range and environmental restrictions on application conditions,when the single quantum dot powder or solution is used for fluorescent probe detection.In this paper,...There are many disadvantages such as small detection range and environmental restrictions on application conditions,when the single quantum dot powder or solution is used for fluorescent probe detection.In this paper,the blue fluorescent silicon quantum dots and green fluorescent carbon quantum dots were prepared,and their fluorescence color changes after mixing in different proportions were investigated under different pH conditions.When the two quantum dots were mixed with a concentration of 0.1 mg·mL^(-1) and a mass ratio of 1:1,the fluorescence color change could be better displayed at a pH from 1 to 14.Meanwhile,the double quantum dots were prepared into two forms(ink and film),successfully realizing the device application of the fluorescent probe.The films and inkjet-printed labels were used to test the spoilage of food(pork,milk,etc.),and the color change data of the labels were collected during the spoilage test.These data were used for neural network training to predict the spoilage changes of foods.展开更多
The combination of SiC quantum dots sensitized inverse opal TiO_(2) photocatalyst is designed in this work and then applied in wastewater purification under simulated sunlight.From various spectroscopic techniques,it ...The combination of SiC quantum dots sensitized inverse opal TiO_(2) photocatalyst is designed in this work and then applied in wastewater purification under simulated sunlight.From various spectroscopic techniques,it is found that electrons transfer directionally from SiC quantum dots to inverse opal TiO_(2),and the energy difference between their conduction/valence bands can reduce the recombination rate of photogenerated carriers and provide a pathway with low interfacial resistance for charge transfer inside the composite.As a result,a typical type-II mechanism is proved to dominate the photoinduced charge transfer process.Meanwhile,the composite achieves excellent photocatalytic performances(the highest apparent kinetic constant of 0.037 min^(-1)),which is 6.2 times(0.006 min^(-1))and 2.1 times(0.018 min^(-1))of the bare inverse opal TiO_(2) and commercial P25 photocatalysts.Therefore,the stability and non-toxicity of SiC quantum dots sensitized inverse opal TiO_(2) composite enables it with great potential in practical photocatalytic applications.展开更多
The fluorescence of graphene oxide quantum dots （GOQDs） that are infiltrated into porous silicon （PSi） is investigated. By dropping activated GOQDs solution onto silanized PSi samples, GOQDs are successfully in- f...The fluorescence of graphene oxide quantum dots （GOQDs） that are infiltrated into porous silicon （PSi） is investigated. By dropping activated GOQDs solution onto silanized PSi samples, GOQDs are successfully in- filtrated into a PSi device. The results indicate that the intensity of the fluorescence of the GOQD-inflltrated multilayer with a high reflection band located at its fluorescence spectra scope is approximately double that of the single layer sample. This indicates that the multilayer GOQD-infiltrated PSi substrate is a suitable material for the preparation of sensitive photoluminescence biosensors.展开更多
Colloidal semiconductor quantum dots(QDs)constitute a perfect material for ink-jet printable large area displays,photovoltaics,light-emitting diode,bio-imaging luminescent markers and many other applications.For this ...Colloidal semiconductor quantum dots(QDs)constitute a perfect material for ink-jet printable large area displays,photovoltaics,light-emitting diode,bio-imaging luminescent markers and many other applications.For this purpose,efficient light emission/absorption and spectral tunability are necessary conditions.These are currently fulfilled by the direct bandgap materials.Si-QDs could offer the solution to major hurdles posed by these materials,namely,toxicity(e.g.,Cd-,Pb-or As-based QDs),scarcity(e.g.,QD with In,Se,Te)and/or instability.Here we show that by combining quantum confinement with dedicated surface engineering,the biggest drawback of Si—the indirect bandgap nature—can be overcome,and a‘direct bandgap’variety of Si-QDs is created.We demonstrate this transformation on chemically synthesized Si-QDs using state-of-the-art optical spectroscopy and theoretical modelling.The carbon surface termination gives rise to drastic modification in electron and hole wavefunctions and radiative transitions between the lowest excited states of electron and hole attain‘direct bandgap-like’(phonon-less)character.This results in efficient fast emission,tunable within the visible spectral range by QD size.These findings are fully justified within a tight-binding theoretical model.When the C surface termination is replaced by oxygen,the emission is converted into the well-known red luminescence,with microsecond decay and limited spectral tunability.In that way,the‘direct bandgap’Si-QDs convert into the‘traditional’indirect bandgap form,thoroughly investigated in the past.展开更多
We review recent advances in the field of quantum dot lasers on silicon. A summary of device performance,reliability, and comparison with similar quantum well lasers grown on silicon will be presented. We consider the...We review recent advances in the field of quantum dot lasers on silicon. A summary of device performance,reliability, and comparison with similar quantum well lasers grown on silicon will be presented. We consider the possibility of scalable, low size, weight, and power nanolasers grown on silicon enabled by quantum dot active regions for future short-reach silicon photonics interconnects.展开更多
Chip-scale integration of optoelectronic devices such as lasers, waveguides, and modulators on silicon is prevailing as a promising approach to realize future ultrahigh speed optical interconnects. We review recent pr...Chip-scale integration of optoelectronic devices such as lasers, waveguides, and modulators on silicon is prevailing as a promising approach to realize future ultrahigh speed optical interconnects. We review recent progress of the direct epitaxy and fabrication of quantum dot （QD） lasers and integrated guided-wave devices on silicon. This approach involves the development of molecular beam epitaxial growth of self- organized QD lasers directly on silicon substrates and their monolithic integration with amorphous silicon waveguides and quantum well electroabsorption modulators. Additionally, we report a preliminary study of long-wavelength （〉 1.3 μm） QD lasers grown on silicon and integrated crystalline silicon waveguides using membrane transfer technology.展开更多
Recent experiments suggest graphene-based materials as candidates for use in future electronic and optoelectronic devices.In this study,we propose a new multilayer quantum dot(QD)superlattice(SL)structure with graphen...Recent experiments suggest graphene-based materials as candidates for use in future electronic and optoelectronic devices.In this study,we propose a new multilayer quantum dot(QD)superlattice(SL)structure with graphene as the core and silicon(Si)as the shell of QD.The Slater-Koster tight-binding method based on Bloch theory is exploited to investigate the band structure and energy states of the graphene/Si QD.Results reveal that the graphene/Si QD is a type-I QD and the ground state is 0.6 eV above the valance band.The results also suggest that the graphene/Si QD can be potentially used to create a sub-bandgap in all Si-based intermediate-band solar cells(IBSC).The energy level hybridization in a SL of graphene/Si QDs is investigated and it is observed that the mini-band formation is under the infuence of inter-dot spacing among QDs.To evaluate the impact of the graphene/Si QD SL on the performance of Si-based solar cells,we design an IBSC based on the graphene/Si QD(QDIBSC)and calculate its short-circuit current density(J_(sc))and carrier generation rate(G)using the 2D fnite diference time domain(FDTD)method.In comparison with the standard Si-based solar cell which records J_(sc)=16.9067 mA/cm^(2)and G=1.48943×10^(28)m^(−3)⋅s^(−1),the graphene/Si QD IBSC with 2 layers of QDs presents Jsc=36.4193 mA/cm^(2)and G=7.94192×10^(28)m^(−3)⋅s^(−1),ofering considerable improvement.Finally,the efects of the number of QD layers(L)and the height of QD(H)on the performance of the graphene/Si QD IBSC are discussed.展开更多
基金supported by the National Natural Science Foundation of China(U22A2075,U20A20209)the Fundamental Research Funds for the Central Universities(226-2022-00200)the Qianjiang Distinguished Experts program of Hangzhou.
文摘Ratiometric fluorescent detection of iron(Ⅲ)(Fe^(3+))offers inherent self-calibration and contactless analytic capabilities.However,realizing a dual-emission near-infrared(NIR)nanosensor with a low limit of detection(LOD)is rather challenging.In this work,we report the synthesis of water-dispersible erbium-hyperdoped silicon quantum dots(Si QDs:Er),which emit NIR light at the wavelengths of 810 and 1540 nm.A dual-emission NIR nanosensor based on water-dispersible Si QDs:Er enables ratiometric Fe^(3+)detection with a very low LOD(0.06μM).The effects of pH,recyclability,and the interplay between static and dynamic quenching mechanisms for Fe^(3+)detection have been systematically studied.In addition,we demonstrate that the nanosensor may be used to construct a sequential logic circuit with memory functions.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60966002)the National Key Laboratory of Surface Physics, Fudan University, China
文摘The emission of silicon quantum dots is weak when their surface is passivated well. Oxygen or nitrogen on the surface of silicon quantum dots can break the passivation to form localized electronic states in the band gap to generate active centers where stronger emission occurs. From this point of view, we can build up radiative matter for emission. Emissions of various wavelengths can be obtained by controlling the surface bonds of silicon quantum dots. Our experimental results demonstrate that annealing is important in the treatment of the activation, and stimulated emissions at about 600 and 700 nm take place on active silicon quantum dots.
基金Supported by the National Natural Science Foundation of China under Grant No 61575216
文摘A series of boron- and phosphorus-doped silicon wafers are used to prepare a series of doped silicon nanocrystals （nc-Si） by high-energy ball milling with carboxylic acid-terminated surface. The sizes of the nc-Si samples are demonstrated to be 〈 S nm. The doping levels of the nc-Si are found to be nonlinearly dependent on the original doping level of the wafers by x-ray photoelectron spectroscopy measurement. It is found that the nonlinear doping process will lead to the nonlinear chemical passivation and photoluminescence （I3L） intensity evolution. The doping, chemical passivation and PL mechanisms of the doped nc-Si samples prepared by mechanochemical synthesis are analyzed in detail.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21374074,21422404,and U1532108)the Undergraduate Training Program for Innovation and Entrepreneurship of Soochow University,China(Grant No.2016xj010)
文摘Imaging-guided cancer therapy provides a simultaneous tumor imaging and treatment, which helps to eliminate the excessive toxicity to the healthy tissues. For this purpose, multifunctional probes capable of both imaging and curing are needed. In this work, we synthesize water-soluble silicon quantum dots（Si QDs） smaller than 5 nm. Such Si QDs are used for delivering the hydrophobic drug phthalocyanine（Pc）. The as-prepared Si/Pc nanocomposite particles show efficient transmembrane delivery into cells and feasible biocompatibility. Moreover, these composite particles emit dualchannel fluorescence signals even after cellular internalization and demonstrate robust photostability in the Si channel.More interestingly, the Si/Pc composite particles show efficient photodynamic therapy effects against tumors both in vitro and in vivo.
基金the National Natural Science Foundation of China(Nos.21874060,22074057 and 21775059).
文摘Fluorescent silicon quantum dots(Si QDs)were hydrothermally synthesized from a mixture of 3(2-aminoethylamino)propyl(dimethoxymethylsilane)(AEAPDMMS)and poly(vinylpyrrolidine)(PVP).The resulting Si QDs exhibited good water solubility and high stability.Under the optimized conditions,the probe revealed an excellent linear fluorescence quenching effect on Co2+ranging from 1μmol/L to 120μmol/L with a limit of detection of 0.37μmol/L(based on 3 s/k).The quenching mechanism was studied,showing that static quenching(SQE)causes the main effect.Furthermore,the test paper based on Si QDs was prepared,which is cost-effective,high sensitivity,good selectivity,easy to use and show excellent anti-interference capability.This method was applied to analyze the content of Co2+in environmental water samples with satisfying results.
基金funded by Chongqing Technical Innovation and Application Development Special General Project(CSTB2022TIAD-LDX0006)Scientific Technological Research Program of Chongqing Municipal Education Commission(KJQN201901501)Research Foundation of Chongqing University of Science and Technology(ckrc2019031)。
文摘Silicon quantum dots(SiQDs)with high water-soluble and favorable photostability were prepared by a one-step hydrothermal method.The average diameter of SiQDs was 2.02 nm characterized by transmission electron microscope.It was to be noted that the as-prepared SiQDs showed eff ective antibacterial activity,which was attributed to electrostatic interaction and the generation of reactive oxygen species.The minimum inhibitory concentration of SiQDs against Escherichia coli and Staphylococcus aureus was 0.45 mg/mL and 0.38 mg/mL,respectively.Besides,based on the static quenching eff ect-induced fluorescence quenching mechanism,the SiQDs exhibited high sensitivity and selectivity for detecting tetracyclines(TC).A good linear relationship was obtained between the fluorescence intensity of SiQDs and the concentration of tetracycline(TC)in the range of 0–0.08μmol/L(R^(2)=0.9993)with a detection limit of 0.0176μmol/L.Furthermore,the TC content in the honey samples was determined using the SiQDs.All the results suggest that the as-prepared SiQDs can be a potential fluorescent probe for application in antibacterial and analysis.
基金supported by National Natural Science Foundation of China(22074154)Longyuan Youth Innovation and Entrepreneurship Talent(Team)Project(E20492SC)+2 种基金Lanzhou talent innovation and Entrepreneurship Project(2021-RC-35)Science and Technology Project of Science and Technology Bureau of Chengguan District in Lanzhou City(2020JSCX0033)Youth Innovation Promotion Association CAS(2021420)
文摘In this paper,silicon quantum dots(SiQDs)with green fluorescence are synthesized by solvothermal reaction of 3-(2,3-epoxypropoxy)propyltrimethoxysilane(GPTMS)and ethylenediaminetetraacetic acid(EDTA),and then SiQDs are bonded to the surface of silica to obtain a new nano-on-micro stationary phase(SiO_(2)-SiQDs)for reversed-phase chromatography.The successful preparation of SiO_(2)-SiQDs stationary phase is demonstrated by a variety of characterizations,such as transmission electron microscopy,laser confocal microscopy,elemental analysis and Fourier infrared spectroscopy.In addition,the chromatographic performance of the prepared stationary phase is evaluated and it shows good separation performance for non-polar substances such as alkylbenzene,aniline and polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography.It is also verified that the stationary phase has good methyl selectivity and shape selectivity.More interestingly,the separation of prednisolone and hydrocortisone isomers can also be achieved at a low ratio of organic solvents,indicating that this new stationary phase has a good application prospect in isomer separation.
基金HBS thanks the Natural Science Foundation of China(NSFC)under Grant Nos.91423102,21273096,91323301 and 11104109the National Basic Research Program of China(973 Program)under Grant No.2014CB921302 for support.
文摘In this work,the fundamental mechanism of ultrabright fluorescence from surface-modified colloidal silicon quantum dots is investigated in depth using ultrafast spectroscopy.The underlying energy band structure corresponding to such highly efficient direct bandgap-like emissions in our surface-modified silicon quantum dots is unraveled by analyzing the transient optical spectrum,which demonstrates the significant effect of surface molecular engineering.It is observed that special surface modification,which creates novel surface states,is responsible for the different emission wavelengths and the significant improvement in the photoluminescence quantum yields.Following this essential understanding,surface-modified silicon quantum dots with deep blue to orange emission are successfully prepared without changing their sizes.
文摘Nowadays the development of Internet of Things （loT） and defense technologies imperatively needs high-performance photodetectors that can work in a broadband wavelength range, in particular, covering the mid-infrared （MIR） region [1]. This generates great interest in the incorporation of a series of novel optoelectronic materials and structures into the photodetectors. Graphene and colloidal quantum dots （QDs） are key players among novel materials used to fabricate high-performance photodetectors [2-4]. By taking advantage of the high mobility of graphene and excellent tunable optical absorption of colloidal QDs,
基金the usage of all characterizations supported by the“14th Five-Year Plan”National Key Research and Development Plan Project(Grant No.2023YFE0105500)National Natural Science Foundation of China(Grant No.52173206)。
文摘There are many disadvantages such as small detection range and environmental restrictions on application conditions,when the single quantum dot powder or solution is used for fluorescent probe detection.In this paper,the blue fluorescent silicon quantum dots and green fluorescent carbon quantum dots were prepared,and their fluorescence color changes after mixing in different proportions were investigated under different pH conditions.When the two quantum dots were mixed with a concentration of 0.1 mg·mL^(-1) and a mass ratio of 1:1,the fluorescence color change could be better displayed at a pH from 1 to 14.Meanwhile,the double quantum dots were prepared into two forms(ink and film),successfully realizing the device application of the fluorescent probe.The films and inkjet-printed labels were used to test the spoilage of food(pork,milk,etc.),and the color change data of the labels were collected during the spoilage test.These data were used for neural network training to predict the spoilage changes of foods.
基金partially supported by the National Natural Science Foundation of China(Grant Nos.51402161,51373086,21606140,and 21776147)the Natural Science Foundation of Shandong Province(Grant No.ZR2021YQ32)the Taishan Scholar Project of Shandong Province(tsqn201909117).
文摘The combination of SiC quantum dots sensitized inverse opal TiO_(2) photocatalyst is designed in this work and then applied in wastewater purification under simulated sunlight.From various spectroscopic techniques,it is found that electrons transfer directionally from SiC quantum dots to inverse opal TiO_(2),and the energy difference between their conduction/valence bands can reduce the recombination rate of photogenerated carriers and provide a pathway with low interfacial resistance for charge transfer inside the composite.As a result,a typical type-II mechanism is proved to dominate the photoinduced charge transfer process.Meanwhile,the composite achieves excellent photocatalytic performances(the highest apparent kinetic constant of 0.037 min^(-1)),which is 6.2 times(0.006 min^(-1))and 2.1 times(0.018 min^(-1))of the bare inverse opal TiO_(2) and commercial P25 photocatalysts.Therefore,the stability and non-toxicity of SiC quantum dots sensitized inverse opal TiO_(2) composite enables it with great potential in practical photocatalytic applications.
基金supported by the National Natural Science Foundation of China(Nos.61575168 and 61265009)the Xinjiang Science and Technology Project(No.201412112)
文摘The fluorescence of graphene oxide quantum dots （GOQDs） that are infiltrated into porous silicon （PSi） is investigated. By dropping activated GOQDs solution onto silanized PSi samples, GOQDs are successfully in- filtrated into a PSi device. The results indicate that the intensity of the fluorescence of the GOQD-inflltrated multilayer with a high reflection band located at its fluorescence spectra scope is approximately double that of the single layer sample. This indicates that the multilayer GOQD-infiltrated PSi substrate is a suitable material for the preparation of sensitive photoluminescence biosensors.
基金This work was financially supported by Stichting der Fundamenteel Onderzoek der Materie and Stichting voor de Technische Wetenschappen.Part of this work(CPU,JMJP andHZ)was financed by the Dutch Polymer Institute for funding of UCin Functional Polymer Systemsproject no.681,and(ANP andAAP)Russian Foundation for Basic Research and‘Dynasty’-Foundation of International Center for Fundamental Physics in Moscow.
文摘Colloidal semiconductor quantum dots(QDs)constitute a perfect material for ink-jet printable large area displays,photovoltaics,light-emitting diode,bio-imaging luminescent markers and many other applications.For this purpose,efficient light emission/absorption and spectral tunability are necessary conditions.These are currently fulfilled by the direct bandgap materials.Si-QDs could offer the solution to major hurdles posed by these materials,namely,toxicity(e.g.,Cd-,Pb-or As-based QDs),scarcity(e.g.,QD with In,Se,Te)and/or instability.Here we show that by combining quantum confinement with dedicated surface engineering,the biggest drawback of Si—the indirect bandgap nature—can be overcome,and a‘direct bandgap’variety of Si-QDs is created.We demonstrate this transformation on chemically synthesized Si-QDs using state-of-the-art optical spectroscopy and theoretical modelling.The carbon surface termination gives rise to drastic modification in electron and hole wavefunctions and radiative transitions between the lowest excited states of electron and hole attain‘direct bandgap-like’(phonon-less)character.This results in efficient fast emission,tunable within the visible spectral range by QD size.These findings are fully justified within a tight-binding theoretical model.When the C surface termination is replaced by oxygen,the emission is converted into the well-known red luminescence,with microsecond decay and limited spectral tunability.In that way,the‘direct bandgap’Si-QDs convert into the‘traditional’indirect bandgap form,thoroughly investigated in the past.
基金supported by DARPA MTO E-PHI and the Semiconductor Research Corporationsupport of NSF graduate research fellowships
文摘We review recent advances in the field of quantum dot lasers on silicon. A summary of device performance,reliability, and comparison with similar quantum well lasers grown on silicon will be presented. We consider the possibility of scalable, low size, weight, and power nanolasers grown on silicon enabled by quantum dot active regions for future short-reach silicon photonics interconnects.
基金the Defense Advanced Research Projects Agency of the United States under Grant No.W911NF-04-1-0429
文摘Chip-scale integration of optoelectronic devices such as lasers, waveguides, and modulators on silicon is prevailing as a promising approach to realize future ultrahigh speed optical interconnects. We review recent progress of the direct epitaxy and fabrication of quantum dot （QD） lasers and integrated guided-wave devices on silicon. This approach involves the development of molecular beam epitaxial growth of self- organized QD lasers directly on silicon substrates and their monolithic integration with amorphous silicon waveguides and quantum well electroabsorption modulators. Additionally, we report a preliminary study of long-wavelength （〉 1.3 μm） QD lasers grown on silicon and integrated crystalline silicon waveguides using membrane transfer technology.
文摘Recent experiments suggest graphene-based materials as candidates for use in future electronic and optoelectronic devices.In this study,we propose a new multilayer quantum dot(QD)superlattice(SL)structure with graphene as the core and silicon(Si)as the shell of QD.The Slater-Koster tight-binding method based on Bloch theory is exploited to investigate the band structure and energy states of the graphene/Si QD.Results reveal that the graphene/Si QD is a type-I QD and the ground state is 0.6 eV above the valance band.The results also suggest that the graphene/Si QD can be potentially used to create a sub-bandgap in all Si-based intermediate-band solar cells(IBSC).The energy level hybridization in a SL of graphene/Si QDs is investigated and it is observed that the mini-band formation is under the infuence of inter-dot spacing among QDs.To evaluate the impact of the graphene/Si QD SL on the performance of Si-based solar cells,we design an IBSC based on the graphene/Si QD(QDIBSC)and calculate its short-circuit current density(J_(sc))and carrier generation rate(G)using the 2D fnite diference time domain(FDTD)method.In comparison with the standard Si-based solar cell which records J_(sc)=16.9067 mA/cm^(2)and G=1.48943×10^(28)m^(−3)⋅s^(−1),the graphene/Si QD IBSC with 2 layers of QDs presents Jsc=36.4193 mA/cm^(2)and G=7.94192×10^(28)m^(−3)⋅s^(−1),ofering considerable improvement.Finally,the efects of the number of QD layers(L)and the height of QD(H)on the performance of the graphene/Si QD IBSC are discussed.
