La_(2)Mg_(1-x/2)Zr_(1-x/2)O_(6):xBi^(3+)(x=0.01-0.035,abbreviated as LMZ:Bi^(3+))and La_(2-y)Mg_(0.99)Zr_(0.99)O_(6):0.02Bi^(3+),yEu^(3+)(y=0.1-0.11,abbreviated as LMZ:Bi^(3+),Eu^(3+))double-perovskite phosphors were ...La_(2)Mg_(1-x/2)Zr_(1-x/2)O_(6):xBi^(3+)(x=0.01-0.035,abbreviated as LMZ:Bi^(3+))and La_(2-y)Mg_(0.99)Zr_(0.99)O_(6):0.02Bi^(3+),yEu^(3+)(y=0.1-0.11,abbreviated as LMZ:Bi^(3+),Eu^(3+))double-perovskite phosphors were prepared through high-temperature solid-phase method.The emission spectrum of LMZ:xBi^(3+)(x=0.01-0.035)phosphors excited at 353 nm is asymmetric in the range between 375 and 650 nm,showing strong green light.There are two luminescent centers of[Mg1/Zr2-O_(6)]and[Mg2/Zr1-O_(6)]for Bi^(3+)occupation,which were analyzed through different excitation wavelengths,Gaussian fitting peaks,fluorescence decay curves and Rietveld refinement of powder X-ray diffraction data.Through deep study of the luminescent lattices in the LMZ matrix,the green to blue tunning-emission is observed by different excitation wavelengths.In addition,red emission is obtained by co-doping Bi^(3+)/Eu^(3+),and adjustable emission was investigated by changing the content of Eu^(3+)in the co-doped phosphor formulation,so it is converted from green emission to red emission.The above results demonstrate how to tune emission color by co-doping rare earth ions in the double perovskite phosphor,which is attractive for future applications.展开更多
Metal-free materials with multicolor tunable circularly polarized luminescence(CPL)are attractive because of their potential applications in information storage and encryption.Here,we designed two enantiomers composed...Metal-free materials with multicolor tunable circularly polarized luminescence(CPL)are attractive because of their potential applications in information storage and encryption.Here,we designed two enantiomers composed of chiral dialkyl glutamides and achiral vibration-induced emission(VIE)moiety,which can switch on CPL after a simple gelation process.It is noteworthy that the CPL colors vary in different solvents,and this is attributed to various self-assembly-induced microstructures,in which the VIE moiety is restrained to different degrees.Accordingly,a multidimensional code system composed of a quick response code,a ultraviolet(UV)light-activated color code,and a CPL information figure was constructed.To our satisfaction,the system possesses multiple information-storage functions.The orthogonal anticounterfeiting and CPLenhanced encryption functions also improve the system information encryption ability.In brief,this study provides a practical example of CPL applied to information security and an effective approach to obtain a single-component color-tunable CPL material with multiple information storage and encryption functions as well.展开更多
Lead sulfide(PbS)quantum dots(QDs)are important near infrared(NIR)luminescent materials with tunable and strong emission covering a broad NIR region.However,their optical properties are quite sensitive to air,water,an...Lead sulfide(PbS)quantum dots(QDs)are important near infrared(NIR)luminescent materials with tunable and strong emission covering a broad NIR region.However,their optical properties are quite sensitive to air,water,and high temperature due to the surface oxidation,thus limiting their applications in optoelectronic devices and biological imaging.Herein,a cation-doping strategy is presented to make a series of high-quality Zn-doped PbS QDs with strong emission covering whole second near-infrared window(NIR-II,1,000-1,700 nm).First-principle calculations confirmed that Zn dopants formed dopant states and decreased the recombination energy gap of host PbS.Notably,the Zn dopants significantly improved the quantum yield,photoluminescence lifetime and thermal stability of PbS QDs.Moreover,the PEGylated Zn-doped PbS QDs emitting in the NIR-llb window(1,500-1,700 nm)realized the noninvasive imaging of cerebral vascular of mouse with high resolution,being able to distinguish blood capillary.This material not only provides a new tool for deep tissue fluorescence imaging,but is also promising for the development of other NIR related devices.展开更多
Nowadays,due to uncontrolled synthesis and lack of more direct and systematic evidences,the photoluminescence origin of“zero-dimensional”Cs4PbI6 remains great controversy and the luminescence cannot be controlled.He...Nowadays,due to uncontrolled synthesis and lack of more direct and systematic evidences,the photoluminescence origin of“zero-dimensional”Cs4PbI6 remains great controversy and the luminescence cannot be controlled.Here we propose a controllable dissolution-recrystallization method to synthesize“emissive”and“non-emissive”Cs4PbI6 nanocrystals(NCs)respectively.Through comparing“emissive”and“non-emissive”Cs4PbI6 NCs,it is clearly proved that the visible emission in“emissive”Cs4PbI6 NCs comes from embedded CsPbI3 quantum dots(QDs).It is found for CsPbI3@Cs4PbI6 nanocomposites,methyl acetate(MeAC)and cyclohexane play an important role in dissolution and recrystallization respectively to obtain Cs4PbI6 matrix and CsPbI3 cores.Benefiting from this two-step method,the as-synthesized CsPbI3@Cs4PbI6 nanocomposites with CsPbI3 QDs uniformly distributed in Cs4PbI6 matrix are bright with photoluminescence quantum yield(PLQY)up to 71.4%and exhibit improved stability than CsPbI3 NCs.Moreover,utilizing its formation mechanism,the size of embedded CsPbI3 QDs can be controlled by reasonable designing the“dissolution”process,so that the luminescence of this CsPbI3@Cs4PbI6 nanocomposites can be adjusted in a wide range from green to red(554–630 nm).Our finding not only provides a novel method for synthesizing tunable“emissive”Cs4PbI6 NCs,but also makes clear the photoluminescence origin of“emissive”Cs4PbI6.展开更多
Carbon dots(CDs),as a new kind of carbon-based luminescent nanomaterials,have drawn widespread attention in the fields of fluorescence sensing,optoelectronic devices,and biological imaging.This work uses citric acid(C...Carbon dots(CDs),as a new kind of carbon-based luminescent nanomaterials,have drawn widespread attention in the fields of fluorescence sensing,optoelectronic devices,and biological imaging.This work uses citric acid(CA)and Nile Blue A(NBA)as precursors.By simply changing the solvent in the reaction,their bandgaps were systematically controlled,thereby successfully obtaining bright blue,yellow and red fluorescence emission CDs(B-,Y-and RCDs).The higher quantum yield(QY)of B-,Y-and RCDs are 64%,57%and 51%,respectively.The selected precursors and different solvents are the key to the formation of three emission CDs.Detailed characterization and density functional theory(DFT)calculations further indicate that the difference in emission color of CDs is due to the size of the sp^(2) conjugate domain.In addition,we used multicolor CDs as fluorescent probes to investigate their performance in detection.Among them,BCDs and YCDs can detect Sudan Red I with high selectivity and sensitivity.In the concentration range of 0 to 80 pM,the detection limits are 56 and 41 nM,respectively.Multicolor emitting phosphors and fluorescent films are also obtained by mixing CDs with other matrices.Using Ultraviolet(UV)chip as the excitation source and combining with multicolor fluorescent film and a certain proportion of B-,Y-,and RCDs/epoxy resin composites,bright monochromatic light-emitting diodes(LEDs)and white LED(WLED)with high color rendering index(CRI)were prepared.The above results indicate that the multicolor CDs prepared by us have great application potential in the fields of food safety control and optical devices.展开更多
A series of aluminoborosilicate glasses were prepared amounts of SiO2, A1203, H3BO3, Na2CO3, and ZrO2 with adding using the melt-quenching technique for mixture of stoichiometric of different amounts of CeO〉 The samp...A series of aluminoborosilicate glasses were prepared amounts of SiO2, A1203, H3BO3, Na2CO3, and ZrO2 with adding using the melt-quenching technique for mixture of stoichiometric of different amounts of CeO〉 The samples were investigated by means of luminescence spectroscopy. Tunable luminescence from violet to blue/green was observed from these glasses with different Xe-lamp excitation wavelengths ranging from 370 to 480 nm as well as with laser excitation of 266 and 355 nm. Moreover it was found that the possibility of tuning the light by changing of excitation wavelength was not unique. The same effect was observed by adjusting conditions for luminescence measurements as well as under exposure to β-irradiation. The obtained phenomena could be explained taking into account structural characteristics of this glass and it could be concluded that tunable luminescence results from the presence of different Ce-sites the glass matrix. Thus the results suggest that Ce-doped glasses could be considered as conversion materials for blue light-emitting diode chips to generate white light-emitting diodes.展开更多
Here,we report a series of Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)(0≤x≤1.0 mol)phosphors by using the traditional high temperature solid-state reaction.To achieve the structural and photoluminescent(PL)information,...Here,we report a series of Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)(0≤x≤1.0 mol)phosphors by using the traditional high temperature solid-state reaction.To achieve the structural and photoluminescent(PL)information,several experimental characterizations and theoretical calculations were carried out,including X-ray diffraction(XRD),Rietveld refinement,UV-visible diffuse reflectance and PL spectra,temperature dependent PL spectra,and density functional theo retical(DFT)calculations.The XRD results show that the Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)samples belong to the double-perovskite phase with a cubic space group of Fm3 m,and the diffraction positions shift toward high diffraction angle when the larger Y^(3+)ions are gradually replaced by the smaller Sc^(3+)ions.In addition,the refined XRD findings show that the Bi^(3+)ions tend to substitute the Y^(3+)and Sc^(3+)sites in the Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)0<x<1.0 mol)solid solutions.The PL spectra show that the emission positions of the solid solution samples tune from446 to 497 nm with the increase of Sc^(3+) content,which can be attributed to the modification of crystal field strength around Bi^(3+)ions.Moreover,there is energy transfer from the Ba_(2)YNbO_(6)host to Bi^(3+)ions,which is dominated by a resonant type via a dipole-quadrupole(d-q)interaction.The Ba_(2)Y_(0.6)Sc_(0.4)NbO_(6):0.02 molBi^(3+)shows the strongest PL intensity under 365 nm excitation,with the best quantum efficiency(QE)of 68%,and it keeps 60%of the room temperature emission intensity when the temperature increases to 150℃,meaning that the Ba_(2)Y_(0.6)Sc_(0.4)NbO_(6):Bi^(3+)features excellent thermal quenching of luminescence.By combining this optimal sample with a commercial red-emitting Sr_(2)Si_(5)N_(8):Eu^(2+)phosphor,and a commercial 365 nm UV LED chip,a white LED device,with the color temperature(CT)of 3678 K,color rendering index(CRI)of 67.9,and CIE coordinates at(0.371,0.376),is achieved.展开更多
A series of single Ce^(3+) doped and Ce^(3+) and Tb^(3+) co-doped Na_(2)BaCa(PO_(4))_(2)(NBCP) phosphors was synthesized by conventional solid-stated reaction method.The crystal structure,luminescence properties,therm...A series of single Ce^(3+) doped and Ce^(3+) and Tb^(3+) co-doped Na_(2)BaCa(PO_(4))_(2)(NBCP) phosphors was synthesized by conventional solid-stated reaction method.The crystal structure,luminescence properties,thermal stability and energy transfer were carefully investigated.Ce^(3+) is inferred to substitute the Ba^(2+)site in NBCP lattice.The color-tunable emission from blue to green is observed by adjusting Tb^(3+) concentration among NBCP:0.03 Ce^(3+),yTb^(3+) phosphors.The energy transfer behavior from Ce^(3+) to Tb^(3+) ions is both illustrated by co-doped PL spectra and decay curves.The energy transfer efficiency is as high as 91.5%.The mechanism of energy transfer is resonance type of dipole-dipole transition.In this work,the optimal phosphor exhibits the excellent thermal stability which keeps at 94.9% of that initial value at room temperature when temperature reaches to 150℃.The Ce^(3+) and Tb^(3+) co-doped NBCP phosphor is a promising candidate for the application in the general lighting and display fields.展开更多
This paper reported the crystal growth and spectroscopy characters of Cr^3＋：Li2Mg2（MoO4）3. The refractive index of Cr^3＋：Li2Mg2（MoO4）3 crystal is 1.87 and the hardness is 270 I-IV. This crystal shows broadband...This paper reported the crystal growth and spectroscopy characters of Cr^3＋：Li2Mg2（MoO4）3. The refractive index of Cr^3＋：Li2Mg2（MoO4）3 crystal is 1.87 and the hardness is 270 I-IV. This crystal shows broadband absorption property with peak wavelength at about 495 and 699 nm. The absorption crosssection is 14.75 × 10^-20 cm^2 at 495 nm and 9.63 ×10^-20 cm^2 at 699 nm, respectively. The crystal field strength and energy levels of Cr^3＋ ion were calculated based on the spectroscopic data. The Cr^3＋：Li2Mg2（MoO4）3 crystal shows broadband emission extending from 750 to 1300 nm even excited at 10 K. The room temperature emission cross section is 72×10^-20 cm^2 at 926 nm. A discussion of the relation between the spectroscopic properties and crystal field parameters of Cr^3＋：Li2Mg2（MoO4）3 crystal was presented based on the solid state spectroscopytheory.展开更多
Localized surface plasmon resonance(LSPR) has caused extensive concern and achieved widespread applications in optoelectronics. However, the weak coupling of plasmons and excitons in a nanometal/semiconductor system r...Localized surface plasmon resonance(LSPR) has caused extensive concern and achieved widespread applications in optoelectronics. However, the weak coupling of plasmons and excitons in a nanometal/semiconductor system remains to be investigated via energy transfer. Herein, bandgap tunable perovskite films were synthesized to adjust the emission peaks,for further coupling with stable localized surface plasmons from gold nanoparticles. The degree of mismatch, using steadystate and transient photoluminescence(PL), was investigated systematically in two different cases of gold nanoparticles that were in direct contacting and insulated. The results demonstrated the process of tuning emission coupled to LSPR via wavelength-dependent photoluminescence intensity in the samples with an insulating spacer. In the direct contact case,the decreased radiative decay rate involves rapid plasmon resonance energy transfer to the perovskite semiconductor and non-radiative energy transfer to metal nanoparticles in the near-field range.展开更多
The expansion of new structures in aggregation-induced emission/aggregation-induced emission enhancement(AIE/AIEE)systems has attracted persistent attention recently,from which more luminescent functional molecules wi...The expansion of new structures in aggregation-induced emission/aggregation-induced emission enhancement(AIE/AIEE)systems has attracted persistent attention recently,from which more luminescent functional molecules with characteristic skeletons are derived to satisfy specialized applications.In this study,a series of derivatives cored by tetraphenyl enamine with various terminal groups were designed and synthesized based on a novel p-πconjugate chain structure(–C=C–N–).Experimental and theoretical studies reveal that attaching modified groups to enamine core is decisive to achieve successful conversion from non-luminance to AIEE-activity.Moreover,due to different substituent effect on electronic structure,molecular conformation and molecular packing,diverse enamine compounds exhibited prominent substituent tunable emission properties,realizing regulated AIEE effect and multicolor emitting.These results not only offer a new method to design AIEgens/AIEEgens with p-πconjugate chain structures,but also provide in-depth knowledge for functional modifications of more novel AIE/AIEE units and materials.展开更多
Ho^(3+)doped ZBLAN glass with 2.0 and 2.9μm emission was prepared.In order to further improve the luminescence of Ho^(3+),halogen ions(Cl,Br,1)were introduced to reduce the maximum phonon energy and phonon state dens...Ho^(3+)doped ZBLAN glass with 2.0 and 2.9μm emission was prepared.In order to further improve the luminescence of Ho^(3+),halogen ions(Cl,Br,1)were introduced to reduce the maximum phonon energy and phonon state density of the sample.At the same time,Nd^(3+)was introduced to transfer the energy to Ho^(3+)pumped with a 793 nm laser(Nd^(3+):4 F5/2,4 F3/2→Ho^(3+):5 I6).The effect of different halogen ion on the luminescent properties of the fluoride halide glass was compared.The results show that the luminescent intensity of infrared increases with the introduction of different halogen ions.By comparison,it is found that the sample with I-has the strongest luminescence of 1064 nm,2.0μm and 2.9μm.This is consistent with the calculated J-O intensity parameters.In addition,the 2.0 and 2.9μm emission of Ho^(3+)pumped with a 450 nm laser will not disappear.A mid-infrared sample with multi-wavelength excitation and multi-wavelength emission can be obtained.Nd^(3+)/Ho^(3+)co-doped fluoride halide glasses with 1064 nm,2.0μm and 2.9μm luminescence were prepared by melt quenching method.The luminescent mechanism and the energy transfer process between the two ions of Nd^(3+)/Ho^(3+)co-doped fluoride halide glass were studied.The J-O parameters,luminescence lifetime and absorption emission cross-sectional area of Ho^(3+)and Nd^(3+)were calculated,respectively.It is found that the value ofΩ2 in the glass matrix increases with the introduction of different halogen ions,whileΩ4 andΩ6 do not change obviously in different glass compositions.This is because the environment of the crystal field around the rare earth ions changes.The crystal phase and phonon energy of the sample were analyzed by X-ray diffraction pattern and a Fourier transform infrared spectrometer,respectively.Based on the above spectra and data(phonon energy is 634.71 cm-1),it can be predicted that Nd^(3+)/Ho^(3+)co-doped fluoride halide glass is a potential mid-infrared luminescent material.展开更多
A self-luminescence KYb3 F10 material was obtained via a mild hydrothermal method.Its structure,morphology and the corresponding luminescence properties were studied.There is a self-luminesce nce based on the effectiv...A self-luminescence KYb3 F10 material was obtained via a mild hydrothermal method.Its structure,morphology and the corresponding luminescence properties were studied.There is a self-luminesce nce based on the effective recombination of electron and hole on surface defects or electronic centers in KYb3 F10.The pH values have significant impact on crystallinity and self-luminescent intensity of target products.With the introduction of Tb3+and Eu3+into KYb3 F10 matrix,a series of color-tunable emission can be achieved.Simultaneously,Tb3+and Eu3+can also affect the self-luminescent intensity of host slightly.Although there is no obvious energy transfer between host and activators,Tb3+has a distinct sensitive effect on Eu3+ascribed to the energy transfer between Tb3+and Eu3+.In addition,the thermal stability was carefully investigated,which demonstrate the materials can be as a candidate in fluorescent lamps and displays.展开更多
Low-frequency flicker noise is usually associated with material defects or imperfection of fabrication procedure. Up to now, there is only very limited knowledge about flicker noise of the topological insulator, whose...Low-frequency flicker noise is usually associated with material defects or imperfection of fabrication procedure. Up to now, there is only very limited knowledge about flicker noise of the topological insulator, whose topologically protected conducting surface is theoretically immune to back scattering. To suppress the bulk conductivity we synthesize antimony doped Bi2Se3 nanowires and conduct transport measurements at cryogenic temperatures. The low-frequency current noise measurement shows that the noise amplitude at the high-drain current regime can be described by Hooge＇s empirical relationship, while the noise level is significantly lower than that predicted by Hooge＇s model near the Dirac point. Furthermore, different frequency responses of noise power spectrum density for specific drain currents at the low drain current regime indicate the complex origin of noise sources of topological insulator.展开更多
Color tunable quantum dots（QDs） based on the Cu, Mn, Ag co-doped Zn In S core and Zn S outer-shell were synthesized by using an eco-friendly method. Core-shell doped QDs with the average size of 3.85 nm were obtaine...Color tunable quantum dots（QDs） based on the Cu, Mn, Ag co-doped Zn In S core and Zn S outer-shell were synthesized by using an eco-friendly method. Core-shell doped QDs with the average size of 3.85 nm were obtained by using a one-pot synthesis followed by a hot injection with n-dodecanethiol（DDT） and oleylamine（OLA） as stabilizers in oil phase. Cu, Mn and Ag ions were introduced as single-dopant or co-dopants during the synthesis, providing an effective means to control the emission color of the QDs. The as-synthesized QDs showed photoluminescence emission ranging from green（530 nm） to near-red（613 nm）, adjusted by doping components, dopant concentration, and Zn/In ratio. Importantly, quasi-white emission has been achieved by controlling the concentration of co-doped metal ions（Mn, Cu and Ag）. The primary results demonstrated the promising potential of co-doped QDs as alternative materials for future high quality white LED applications.展开更多
基金Project supported by the National Natural Science Foundation of China(51672063,52161145401)the Key Platform Program of Department of Education of Guangdong Province,China(2021ZDZX1003)。
文摘La_(2)Mg_(1-x/2)Zr_(1-x/2)O_(6):xBi^(3+)(x=0.01-0.035,abbreviated as LMZ:Bi^(3+))and La_(2-y)Mg_(0.99)Zr_(0.99)O_(6):0.02Bi^(3+),yEu^(3+)(y=0.1-0.11,abbreviated as LMZ:Bi^(3+),Eu^(3+))double-perovskite phosphors were prepared through high-temperature solid-phase method.The emission spectrum of LMZ:xBi^(3+)(x=0.01-0.035)phosphors excited at 353 nm is asymmetric in the range between 375 and 650 nm,showing strong green light.There are two luminescent centers of[Mg1/Zr2-O_(6)]and[Mg2/Zr1-O_(6)]for Bi^(3+)occupation,which were analyzed through different excitation wavelengths,Gaussian fitting peaks,fluorescence decay curves and Rietveld refinement of powder X-ray diffraction data.Through deep study of the luminescent lattices in the LMZ matrix,the green to blue tunning-emission is observed by different excitation wavelengths.In addition,red emission is obtained by co-doping Bi^(3+)/Eu^(3+),and adjustable emission was investigated by changing the content of Eu^(3+)in the co-doped phosphor formulation,so it is converted from green emission to red emission.The above results demonstrate how to tune emission color by co-doping rare earth ions in the double perovskite phosphor,which is attractive for future applications.
基金support from the National Key Research and Development Program of China(grant no.2022YFB3203500)the National Natural Science Foundation of China(grant nos.21788102,22125803,and 22020102006)+2 种基金project support by the Shanghai Municipal Science and Technology Major Project(grant no.2018SHZDZX03)the Program of Shanghai Academic/Technology Research Leader(grant no.20XD1421300)the Fundamental Research Funds for the Central Universities.
文摘Metal-free materials with multicolor tunable circularly polarized luminescence(CPL)are attractive because of their potential applications in information storage and encryption.Here,we designed two enantiomers composed of chiral dialkyl glutamides and achiral vibration-induced emission(VIE)moiety,which can switch on CPL after a simple gelation process.It is noteworthy that the CPL colors vary in different solvents,and this is attributed to various self-assembly-induced microstructures,in which the VIE moiety is restrained to different degrees.Accordingly,a multidimensional code system composed of a quick response code,a ultraviolet(UV)light-activated color code,and a CPL information figure was constructed.To our satisfaction,the system possesses multiple information-storage functions.The orthogonal anticounterfeiting and CPLenhanced encryption functions also improve the system information encryption ability.In brief,this study provides a practical example of CPL applied to information security and an effective approach to obtain a single-component color-tunable CPL material with multiple information storage and encryption functions as well.
基金This work was supported by the National Natural Science Foundation of China(Nos.21974104 and 21703221)the National Postdoctoral Science Foundation of China(No.2012T50663).
文摘Lead sulfide(PbS)quantum dots(QDs)are important near infrared(NIR)luminescent materials with tunable and strong emission covering a broad NIR region.However,their optical properties are quite sensitive to air,water,and high temperature due to the surface oxidation,thus limiting their applications in optoelectronic devices and biological imaging.Herein,a cation-doping strategy is presented to make a series of high-quality Zn-doped PbS QDs with strong emission covering whole second near-infrared window(NIR-II,1,000-1,700 nm).First-principle calculations confirmed that Zn dopants formed dopant states and decreased the recombination energy gap of host PbS.Notably,the Zn dopants significantly improved the quantum yield,photoluminescence lifetime and thermal stability of PbS QDs.Moreover,the PEGylated Zn-doped PbS QDs emitting in the NIR-llb window(1,500-1,700 nm)realized the noninvasive imaging of cerebral vascular of mouse with high resolution,being able to distinguish blood capillary.This material not only provides a new tool for deep tissue fluorescence imaging,but is also promising for the development of other NIR related devices.
基金supported by the National Natural Science Foundation of China (21971185 and 52173177)the Natural Science Foundation of Jiangsu Province (BK20230010 and BK20221362)+4 种基金the Science and Technology Support Program of Jiangsu Province (TJ-2022-002)funded by the Collaborative Innovation Center of Suzhou Nano Science&Technologythe 111 Projectthe Joint International Research Laboratory of Carbon-Based Functional Materials and DevicesSoochow University Tang Scholar。
基金This work was financially supported by the Joint Funds of the National Natural Science Foundation of China and Yunnan Province(No.U1902222)the National Natural Science Foundation of China(Nos.51961145101 and 52102195)+3 种基金China Postdoctoral Science Foundation(Nos.2020M672960 and 2021M703656)Guangzhou Science&Technology Project(No.202007020005)Hunan High Level Talent Gathering Project(Nos.2019RS1077 and 2020RC5007)the Guangdong Provincial Key Laboratory of Semiconductor Micro Display(No.2020B121202003)。
文摘Nowadays,due to uncontrolled synthesis and lack of more direct and systematic evidences,the photoluminescence origin of“zero-dimensional”Cs4PbI6 remains great controversy and the luminescence cannot be controlled.Here we propose a controllable dissolution-recrystallization method to synthesize“emissive”and“non-emissive”Cs4PbI6 nanocrystals(NCs)respectively.Through comparing“emissive”and“non-emissive”Cs4PbI6 NCs,it is clearly proved that the visible emission in“emissive”Cs4PbI6 NCs comes from embedded CsPbI3 quantum dots(QDs).It is found for CsPbI3@Cs4PbI6 nanocomposites,methyl acetate(MeAC)and cyclohexane play an important role in dissolution and recrystallization respectively to obtain Cs4PbI6 matrix and CsPbI3 cores.Benefiting from this two-step method,the as-synthesized CsPbI3@Cs4PbI6 nanocomposites with CsPbI3 QDs uniformly distributed in Cs4PbI6 matrix are bright with photoluminescence quantum yield(PLQY)up to 71.4%and exhibit improved stability than CsPbI3 NCs.Moreover,utilizing its formation mechanism,the size of embedded CsPbI3 QDs can be controlled by reasonable designing the“dissolution”process,so that the luminescence of this CsPbI3@Cs4PbI6 nanocomposites can be adjusted in a wide range from green to red(554–630 nm).Our finding not only provides a novel method for synthesizing tunable“emissive”Cs4PbI6 NCs,but also makes clear the photoluminescence origin of“emissive”Cs4PbI6.
基金supported by the National Natural Science Foundation of China(Nos.51678409,51638011,and 51578375)Tianjin Research Program of Application Foundation and Advanced Technology(Nos.19JCYBJC19800,18JCYBJC87500,and 15ZCZDSF00880)+1 种基金State Key Laboratory of Separation Membranes and Membrane Processes(Z1-201507)the Program for Innovative Research Team in University of Tianjin(TD13-5042).
文摘Carbon dots(CDs),as a new kind of carbon-based luminescent nanomaterials,have drawn widespread attention in the fields of fluorescence sensing,optoelectronic devices,and biological imaging.This work uses citric acid(CA)and Nile Blue A(NBA)as precursors.By simply changing the solvent in the reaction,their bandgaps were systematically controlled,thereby successfully obtaining bright blue,yellow and red fluorescence emission CDs(B-,Y-and RCDs).The higher quantum yield(QY)of B-,Y-and RCDs are 64%,57%and 51%,respectively.The selected precursors and different solvents are the key to the formation of three emission CDs.Detailed characterization and density functional theory(DFT)calculations further indicate that the difference in emission color of CDs is due to the size of the sp^(2) conjugate domain.In addition,we used multicolor CDs as fluorescent probes to investigate their performance in detection.Among them,BCDs and YCDs can detect Sudan Red I with high selectivity and sensitivity.In the concentration range of 0 to 80 pM,the detection limits are 56 and 41 nM,respectively.Multicolor emitting phosphors and fluorescent films are also obtained by mixing CDs with other matrices.Using Ultraviolet(UV)chip as the excitation source and combining with multicolor fluorescent film and a certain proportion of B-,Y-,and RCDs/epoxy resin composites,bright monochromatic light-emitting diodes(LEDs)and white LED(WLED)with high color rendering index(CRI)were prepared.The above results indicate that the multicolor CDs prepared by us have great application potential in the fields of food safety control and optical devices.
文摘A series of aluminoborosilicate glasses were prepared amounts of SiO2, A1203, H3BO3, Na2CO3, and ZrO2 with adding using the melt-quenching technique for mixture of stoichiometric of different amounts of CeO〉 The samples were investigated by means of luminescence spectroscopy. Tunable luminescence from violet to blue/green was observed from these glasses with different Xe-lamp excitation wavelengths ranging from 370 to 480 nm as well as with laser excitation of 266 and 355 nm. Moreover it was found that the possibility of tuning the light by changing of excitation wavelength was not unique. The same effect was observed by adjusting conditions for luminescence measurements as well as under exposure to β-irradiation. The obtained phenomena could be explained taking into account structural characteristics of this glass and it could be concluded that tunable luminescence results from the presence of different Ce-sites the glass matrix. Thus the results suggest that Ce-doped glasses could be considered as conversion materials for blue light-emitting diode chips to generate white light-emitting diodes.
基金Project supported by the Key R&D Project of Hebei Province(18214321)the Research Foundation of Hengshui University for High-level Talents(2019GC10)+1 种基金National Innovation and Entrepreneurship Training Program for College Students(202010101001)the Science Technology Program of Hengshui city(2018011002Z)。
文摘Here,we report a series of Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)(0≤x≤1.0 mol)phosphors by using the traditional high temperature solid-state reaction.To achieve the structural and photoluminescent(PL)information,several experimental characterizations and theoretical calculations were carried out,including X-ray diffraction(XRD),Rietveld refinement,UV-visible diffuse reflectance and PL spectra,temperature dependent PL spectra,and density functional theo retical(DFT)calculations.The XRD results show that the Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)samples belong to the double-perovskite phase with a cubic space group of Fm3 m,and the diffraction positions shift toward high diffraction angle when the larger Y^(3+)ions are gradually replaced by the smaller Sc^(3+)ions.In addition,the refined XRD findings show that the Bi^(3+)ions tend to substitute the Y^(3+)and Sc^(3+)sites in the Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)0<x<1.0 mol)solid solutions.The PL spectra show that the emission positions of the solid solution samples tune from446 to 497 nm with the increase of Sc^(3+) content,which can be attributed to the modification of crystal field strength around Bi^(3+)ions.Moreover,there is energy transfer from the Ba_(2)YNbO_(6)host to Bi^(3+)ions,which is dominated by a resonant type via a dipole-quadrupole(d-q)interaction.The Ba_(2)Y_(0.6)Sc_(0.4)NbO_(6):0.02 molBi^(3+)shows the strongest PL intensity under 365 nm excitation,with the best quantum efficiency(QE)of 68%,and it keeps 60%of the room temperature emission intensity when the temperature increases to 150℃,meaning that the Ba_(2)Y_(0.6)Sc_(0.4)NbO_(6):Bi^(3+)features excellent thermal quenching of luminescence.By combining this optimal sample with a commercial red-emitting Sr_(2)Si_(5)N_(8):Eu^(2+)phosphor,and a commercial 365 nm UV LED chip,a white LED device,with the color temperature(CT)of 3678 K,color rendering index(CRI)of 67.9,and CIE coordinates at(0.371,0.376),is achieved.
基金Project supported by The National Natural Science Foundation of China(51772330,51472273)the Natural Science Foundation of Hunan Province(2017JJ2403)the Key Research Foundation of Education Bureau of Hunan Province(16A220)。
文摘A series of single Ce^(3+) doped and Ce^(3+) and Tb^(3+) co-doped Na_(2)BaCa(PO_(4))_(2)(NBCP) phosphors was synthesized by conventional solid-stated reaction method.The crystal structure,luminescence properties,thermal stability and energy transfer were carefully investigated.Ce^(3+) is inferred to substitute the Ba^(2+)site in NBCP lattice.The color-tunable emission from blue to green is observed by adjusting Tb^(3+) concentration among NBCP:0.03 Ce^(3+),yTb^(3+) phosphors.The energy transfer behavior from Ce^(3+) to Tb^(3+) ions is both illustrated by co-doped PL spectra and decay curves.The energy transfer efficiency is as high as 91.5%.The mechanism of energy transfer is resonance type of dipole-dipole transition.In this work,the optimal phosphor exhibits the excellent thermal stability which keeps at 94.9% of that initial value at room temperature when temperature reaches to 150℃.The Ce^(3+) and Tb^(3+) co-doped NBCP phosphor is a promising candidate for the application in the general lighting and display fields.
基金supported by the National Natural Science Foundation of China(Nos.61308085 and 61475158)
文摘This paper reported the crystal growth and spectroscopy characters of Cr^3＋：Li2Mg2（MoO4）3. The refractive index of Cr^3＋：Li2Mg2（MoO4）3 crystal is 1.87 and the hardness is 270 I-IV. This crystal shows broadband absorption property with peak wavelength at about 495 and 699 nm. The absorption crosssection is 14.75 × 10^-20 cm^2 at 495 nm and 9.63 ×10^-20 cm^2 at 699 nm, respectively. The crystal field strength and energy levels of Cr^3＋ ion were calculated based on the spectroscopic data. The Cr^3＋：Li2Mg2（MoO4）3 crystal shows broadband emission extending from 750 to 1300 nm even excited at 10 K. The room temperature emission cross section is 72×10^-20 cm^2 at 926 nm. A discussion of the relation between the spectroscopic properties and crystal field parameters of Cr^3＋：Li2Mg2（MoO4）3 crystal was presented based on the solid state spectroscopytheory.
基金Project supported by the National Key R&D Program of China (Grant Nos. 2017YFA0700503 and 2018YFA0209101)the National Natural Science Foundation of China (Grant Nos. 61821002, 11734005, 62075041, and 61704024)。
文摘Localized surface plasmon resonance(LSPR) has caused extensive concern and achieved widespread applications in optoelectronics. However, the weak coupling of plasmons and excitons in a nanometal/semiconductor system remains to be investigated via energy transfer. Herein, bandgap tunable perovskite films were synthesized to adjust the emission peaks,for further coupling with stable localized surface plasmons from gold nanoparticles. The degree of mismatch, using steadystate and transient photoluminescence(PL), was investigated systematically in two different cases of gold nanoparticles that were in direct contacting and insulated. The results demonstrated the process of tuning emission coupled to LSPR via wavelength-dependent photoluminescence intensity in the samples with an insulating spacer. In the direct contact case,the decreased radiative decay rate involves rapid plasmon resonance energy transfer to the perovskite semiconductor and non-radiative energy transfer to metal nanoparticles in the near-field range.
基金the National Natural Science Foundation of China(21574003)。
文摘The expansion of new structures in aggregation-induced emission/aggregation-induced emission enhancement(AIE/AIEE)systems has attracted persistent attention recently,from which more luminescent functional molecules with characteristic skeletons are derived to satisfy specialized applications.In this study,a series of derivatives cored by tetraphenyl enamine with various terminal groups were designed and synthesized based on a novel p-πconjugate chain structure(–C=C–N–).Experimental and theoretical studies reveal that attaching modified groups to enamine core is decisive to achieve successful conversion from non-luminance to AIEE-activity.Moreover,due to different substituent effect on electronic structure,molecular conformation and molecular packing,diverse enamine compounds exhibited prominent substituent tunable emission properties,realizing regulated AIEE effect and multicolor emitting.These results not only offer a new method to design AIEgens/AIEEgens with p-πconjugate chain structures,but also provide in-depth knowledge for functional modifications of more novel AIE/AIEE units and materials.
基金Project supported by the National Key Foundation for Exploring Scientific Instrument of China(2014YQ120351)National Natural Science Foundation of China(11504266,51702235,51871167)the Natural Science Foundation of Tianjin,China(17JCQNJC02300,18JCYBJC86200)。
文摘Ho^(3+)doped ZBLAN glass with 2.0 and 2.9μm emission was prepared.In order to further improve the luminescence of Ho^(3+),halogen ions(Cl,Br,1)were introduced to reduce the maximum phonon energy and phonon state density of the sample.At the same time,Nd^(3+)was introduced to transfer the energy to Ho^(3+)pumped with a 793 nm laser(Nd^(3+):4 F5/2,4 F3/2→Ho^(3+):5 I6).The effect of different halogen ion on the luminescent properties of the fluoride halide glass was compared.The results show that the luminescent intensity of infrared increases with the introduction of different halogen ions.By comparison,it is found that the sample with I-has the strongest luminescence of 1064 nm,2.0μm and 2.9μm.This is consistent with the calculated J-O intensity parameters.In addition,the 2.0 and 2.9μm emission of Ho^(3+)pumped with a 450 nm laser will not disappear.A mid-infrared sample with multi-wavelength excitation and multi-wavelength emission can be obtained.Nd^(3+)/Ho^(3+)co-doped fluoride halide glasses with 1064 nm,2.0μm and 2.9μm luminescence were prepared by melt quenching method.The luminescent mechanism and the energy transfer process between the two ions of Nd^(3+)/Ho^(3+)co-doped fluoride halide glass were studied.The J-O parameters,luminescence lifetime and absorption emission cross-sectional area of Ho^(3+)and Nd^(3+)were calculated,respectively.It is found that the value ofΩ2 in the glass matrix increases with the introduction of different halogen ions,whileΩ4 andΩ6 do not change obviously in different glass compositions.This is because the environment of the crystal field around the rare earth ions changes.The crystal phase and phonon energy of the sample were analyzed by X-ray diffraction pattern and a Fourier transform infrared spectrometer,respectively.Based on the above spectra and data(phonon energy is 634.71 cm-1),it can be predicted that Nd^(3+)/Ho^(3+)co-doped fluoride halide glass is a potential mid-infrared luminescent material.
基金Project supported by the National Natural Science Foundation of China(11864038)Natural Science Foundation of Gansu Province of China(18YF1NA104)+1 种基金the Scientific Research Projects of Gansu Colleges and Universities(2017A-009)Undergraduate Innovation Enhancement Program of Northwest Normal University (NWNU2019KT234,NWNU2019CX167)。
文摘A self-luminescence KYb3 F10 material was obtained via a mild hydrothermal method.Its structure,morphology and the corresponding luminescence properties were studied.There is a self-luminesce nce based on the effective recombination of electron and hole on surface defects or electronic centers in KYb3 F10.The pH values have significant impact on crystallinity and self-luminescent intensity of target products.With the introduction of Tb3+and Eu3+into KYb3 F10 matrix,a series of color-tunable emission can be achieved.Simultaneously,Tb3+and Eu3+can also affect the self-luminescent intensity of host slightly.Although there is no obvious energy transfer between host and activators,Tb3+has a distinct sensitive effect on Eu3+ascribed to the energy transfer between Tb3+and Eu3+.In addition,the thermal stability was carefully investigated,which demonstrate the materials can be as a candidate in fluorescent lamps and displays.
基金Supported by the National Basic Research Program of China under Grant No 2012CB921703the National Natural Science Foundation of China under Grant Nos 11174357 and 11574379the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDB07010300
文摘Low-frequency flicker noise is usually associated with material defects or imperfection of fabrication procedure. Up to now, there is only very limited knowledge about flicker noise of the topological insulator, whose topologically protected conducting surface is theoretically immune to back scattering. To suppress the bulk conductivity we synthesize antimony doped Bi2Se3 nanowires and conduct transport measurements at cryogenic temperatures. The low-frequency current noise measurement shows that the noise amplitude at the high-drain current regime can be described by Hooge＇s empirical relationship, while the noise level is significantly lower than that predicted by Hooge＇s model near the Dirac point. Furthermore, different frequency responses of noise power spectrum density for specific drain currents at the low drain current regime indicate the complex origin of noise sources of topological insulator.
基金Projects(61675049,61377046,61144010,61177021) supported by the National Natural Science Foundation of China
文摘Color tunable quantum dots（QDs） based on the Cu, Mn, Ag co-doped Zn In S core and Zn S outer-shell were synthesized by using an eco-friendly method. Core-shell doped QDs with the average size of 3.85 nm were obtained by using a one-pot synthesis followed by a hot injection with n-dodecanethiol（DDT） and oleylamine（OLA） as stabilizers in oil phase. Cu, Mn and Ag ions were introduced as single-dopant or co-dopants during the synthesis, providing an effective means to control the emission color of the QDs. The as-synthesized QDs showed photoluminescence emission ranging from green（530 nm） to near-red（613 nm）, adjusted by doping components, dopant concentration, and Zn/In ratio. Importantly, quasi-white emission has been achieved by controlling the concentration of co-doped metal ions（Mn, Cu and Ag）. The primary results demonstrated the promising potential of co-doped QDs as alternative materials for future high quality white LED applications.
