The enhancement of the intensity of red upconversion(UC)emission has significant implications for biological applications.In KZnF_(3):Yb^(3+),Er^(3+)which inherently produces high-purity red emission,the introduction ...The enhancement of the intensity of red upconversion(UC)emission has significant implications for biological applications.In KZnF_(3):Yb^(3+),Er^(3+)which inherently produces high-purity red emission,the introduction of Fe^(3+)markedly improves the UC intensity by a factor of 13.The mechanism behind the enhanced UC red luminescence is deduced to originate from the Yb^(3+)-Fe^(3+)dimer,as determined by first principle calculation and analysis of UC luminescence properties.The thermometry performance,based on splitting peaks of red emission,demonstrated enhanced temperature sensitivity at lower ranges.Exploring the photothermal properties,it was observed that temperature exhibited a linear correlation with pump power under a 980 nm laser,achieving levels up to 48℃.This temperature range is ideal for applications in mild photothermal therapy(MPTT).This work elucidates the material’s potential in advanced biological applications,merging optical thermometry and photothermics,indicating its multifunctional utility.展开更多
4-Nonylphenol(NP)is a kind of estrogen belonging to the endocrine disrupter,widely used in various agricultural and industrial goods.However,extensive use of NP with direct release to environment poses high risks to b...4-Nonylphenol(NP)is a kind of estrogen belonging to the endocrine disrupter,widely used in various agricultural and industrial goods.However,extensive use of NP with direct release to environment poses high risks to both human health and ecosystems.Herein,for the first time,we developed near-infrared(NIR)responsive upconversion luminescence nanosensor for NP detection.The Förster resonance energy transfer based upconversion nanoparticles(UCNPs)-graphene oxide sensor offers highly selective and sensitive detection of NP in linear ranges of 5−200 ng/mL and 200−1000 ng/mL under 980 nm and 808 nm excitation,respectively,with LOD at 4.2 ng/mL.The sensors were successfully tested for NP detection in real liquid milk samples with excellent recovery results.The rare-earth fluoride based upconversion luminescence nanosensor with NIR excitation wavelength,holds promise for sensing food,environmental,and biological samples due to their high sensitivity,specific recognition,low LOD,negligible autofluorescence,along with the deep penetration of NIR excitation sources.展开更多
Very recently,upconversion luminescence(UCL)lifetime,as a powerful optical dimension,has attracted tremendous research interest due to its advantages of high information capacity and high photophysical stability.With ...Very recently,upconversion luminescence(UCL)lifetime,as a powerful optical dimension,has attracted tremendous research interest due to its advantages of high information capacity and high photophysical stability.With the implementation and emergence of endlessly fascinating UCL features,it is particularly meaningful to understand the photophysical mechanisms inside UCL materials to enable rational subdivision-level structure design,which is however currently far from sufficient.In this work,we take an ordinary upconversion nanoparticle as an example to prove that the UCL decay curves and corresponding lifetimes are indeed a collective response of the entire UCL system to excitations,that exhibits correlated,yet quite different properties from individual ions.A specially developed theoretical random walk model combined with an experimental lifetime control for Yb^(3+)/Er^(3+)UCL demonstrates that ene rgy diffusion principally alters the decay rate.Moreover,the different extent of the influence of energy diffusion on the emissions of ^(2)H_(11/2)/^(4)S_(3/2)(green)and ^(4)F_(9/2)(red)leads to an extremely uncommon crossover comparison of decay rates.This work provides new ideas for understanding decay dynamics and practical UCL lifetime manipulation methods.展开更多
Ultraviolet upconversion photoluminescence materials have great potential in various fields,but the improvement of the upconversion efficiency is challenging.Codoping of Li^(+)is considered as an effective strategy an...Ultraviolet upconversion photoluminescence materials have great potential in various fields,but the improvement of the upconversion efficiency is challenging.Codoping of Li^(+)is considered as an effective strategy and widely used to improve the photoluminescence properties of phosphors.In this paper,Li^(+)is introduced into a Y_(7)O_(6)F_(9):Pr^(3+),Gd^(3+)system.The effect of Li^(+)codoping on the phase purity,crystal structure,micro structure,downshifting and upconversion photo luminescence as well as the decay dynamic of the phosphors was studied.It is revealed that the overall photoluminescence efficiency and the energy transfer efficiency from pr^(3+)to Gd^(3+)are greatly promoted.The downshifting and upconversion photoluminescence increase by 2.58 and 10 times as 6 mol%of Li^(+)is codoped.The photo luminescence decay dynamic study shows that the ^(3)P_(0)state decays slower in the Li^(+)-containing phosphor than the Li^(+)-free one.The improvement of the photoluminescence properties is due to the increase of the crystallinity and the reduce of the quenching center.展开更多
Lanthanide-sensitized upconverting nanoparticles(UCNPs)are widely studied because of their unusual optical characteristics,such as large antenna-generated anti-Stokes shifts,high photostability,and narrow emission ban...Lanthanide-sensitized upconverting nanoparticles(UCNPs)are widely studied because of their unusual optical characteristics,such as large antenna-generated anti-Stokes shifts,high photostability,and narrow emission bandwidths,which can be harnessed for a variety of applications including bioimaging,sensing,information security and high-level anticounterfeiting.The diverse requirements of these applications typically require precise control over upconversion luminescence(UCL).Recently,the concept of energy migration upconversion has emerged as an effective approach to modulate UCL for various lanthanide ions.Moreover,it provides valuable insights into the fundamental comprehension of energy transfer mechanisms on the nanoscale,thereby contributing to the design of efficient lanthanide-sensitized UCNPs and their practical applications.Here we present a comprehensive overview of the latest developments in energy migration upconversion in lanthanide-sensitized nanoparticles for photon upconversion tuning,encompassing design strategies,mechanistic investigations and applications.Additionally,some future prospects in the field of energy migration upconversion are also discussed.展开更多
In this work,rare earth ions(REs)including Yb^(3+)/Er^(3+),Yb^(3+)/Ho^(3+)and Yb^(3+)/Tm^(3+)co-doped manganese oxyfluoride glasses were fabricated using melt quenching method.By fully utilizing the upconversion lumin...In this work,rare earth ions(REs)including Yb^(3+)/Er^(3+),Yb^(3+)/Ho^(3+)and Yb^(3+)/Tm^(3+)co-doped manganese oxyfluoride glasses were fabricated using melt quenching method.By fully utilizing the upconversion luminescence(UCL)of REs and regulating energy transfer between the different energy levels of RE ions and the4T1level of Mn^(2+),the output of UCL was regulated and even pure-red light can be achieved.Moreover,owing to the selective partitioning caused by phase-separation network structure in the oxyfluoride glass,the UCL intensity of glasses annealed for 72 h is significantly enhanced 58 times compared to the rapidly quenched samples.展开更多
Organic afterglow materials hold significant potential for applications in information storage,anticounterfeiting,and biological imaging.However,studies on afterglow materials capable of ultra-wide range excitation an...Organic afterglow materials hold significant potential for applications in information storage,anticounterfeiting,and biological imaging.However,studies on afterglow materials capable of ultra-wide range excitation and emission simultaneously are limited.To enhance the practicality of strong emission single-component organic afterglow systems,overcoming the constraints of crystalline or other rigid environments is essential.We have developed solid-state dual-persistent thermally activated delayed fluorescence(TADF)and room temperature phosphorescence(RTP)emissions spanning yellow to red under visible light excitation,utilizing a single-molecule terminal group regulation strategy.The RTP lifetime extends from 4.19 ms to 399.70 ms.These afterglow materials exhibit an ultra-wide absorption range from 200 nm to 800 nm,rendering them capable of being excited by both sunlight simulator and nearinfrared radiation.The upconversion phosphorescence lifetime under 808 nm excitation reaches 13.72μs.The double persistent emission of these compounds is temperature-sensitive.Moreover,following grinding or heat treatment,accompanied by extensive afterglow color conversion due to planarization of excited state conformations and additional efficient kRIsc generation.In addition,the amorphous state post melt annealing facilitates the afterglow transition from yellow to green.Crucially,these compounds also maintain stable ultra-long afterglow emission in aqueous and acid-base environments.Overall,we have successfully developed a series of single-component intelligent luminescent materials that demonstrate significant benefits,including dual TADF and RTP emissions,adjustable afterglow lifetimes,a broad range of excitation and emission wavelengths,multi-modal luminescence not restricted to crystalline states,and robust afterglow performance in challenging environments,setting the stage for the practical deployment of afterglow materials in engineering applications,the upconversion afterglow emission also holds promising potential for applications in the field of biological imaging.展开更多
Polarization upconversion luminescence(PUCL)of lanthanide ions(Ln^(3+))has been widely used in single particle tracking,microfluidics detection,three-dimensional displays,and so on.However,no effective strategy has be...Polarization upconversion luminescence(PUCL)of lanthanide ions(Ln^(3+))has been widely used in single particle tracking,microfluidics detection,three-dimensional displays,and so on.However,no effective strategy has been developed for modulating PUCL.Here we report a strategy to regulate PUCL in Ho^(3+)-doped NaYF4single nanorods based on the number of upconversion photons.By constructing a multiphoton upconversion system for Ho^(3+),we regulate the degree of polarization(DOP)of PUCL from 0.590 for two-photon luminescence to 0.929 for three-photon upconversion luminescence(UCL).Furthermore,our strategy is verified from cross-relaxation between Ho^(3+)and Yb^(3+),excitation wavelength,excitation power density,and local site symmetry.And this regulation strategy of PUCL has also been achieved in Tm^(3+),with the DOP ranging from 0.233 for two-photon luminescence to 0.925 for four-photon UCL Besides,multi-dimensional anti-counterfeiting display has been explored with PUCL.This work provides an effective strategy for regulating PUCL and also provides more opportunities for the development of polarization display optical encoding,anti-counterfeiting,and integrated optical devices.展开更多
Heavily doped upconversion nanoparticles(UCNPs)potentially have exceptional photon upconversion abilities that are promising for diverse applications,such as lasing and super-resolution microscopy.However,heavily dope...Heavily doped upconversion nanoparticles(UCNPs)potentially have exceptional photon upconversion abilities that are promising for diverse applications,such as lasing and super-resolution microscopy.However,heavily doped UCNPs typically can only offer mediocre upconversion luminescence intensity,and there still lacks general guidelines for the design and synthesis of heavily doped UCNPs.Herein,in order to boost the upconversion luminescence of heavily doped UCNPs,we studied the influence of characteristics of the core-shell structure on heavily doped UCNPs'upconversion luminescence.We find that some empirical guidelines derived from conventional UCNPs are not suitable for heavily doped UCNPs.Using NaYbF_(4):Tm@NaYF_(4) core-shell UCNPs with a high concentration of Yb_(3+)as a representative,our studies reveal that a rather thick inert NaYF4 shell is needed to protect the UCNPs from surface quenching,and the upconversion luminescence may undergo the cooperative sensitization process,which should be due to the highly concentrated Yb~(3+)dopant.In addition,the upconversion luminescence of heavily doped NaYbF4:Tm UCNPs exhibits no obvious dependence on the type of inert shell.Furthermore,our results show that confining both Yb~(3+)and Tm~(3+)dopants in a thin layer(known as theδ-doping strategy)does not work well in the heavily doped UCNPs.Accordingly,we propose a NaYbF_(4):Tm@NaYbF_(4)@NaYF_(4) core-shell-shell structure to enhance the luminescence of heavily doped UCNPs,by weakening the dissipation of excitation energy and strengthening the absorption.These findings should be helpful to establish general design principles for developing the brightest possible UCNPs that can meet the requirements of various applications.展开更多
In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as...In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as-prepared samples was analyzed by X-ray diffraction(XRD),XRD Rietveld refinement and Fourier transform infrared(FT-IR) spectroscopy.The as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er^(3+) doping concentration up to 15 at%.High-purity upconversion(UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er^(3+) ions in the self-activated KYb(MoO_(4))_(2) host is revealed as 3 at%.The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC spectra.In addition,the fluorescence intensity ratios(FIRs) of the two thermally-coupled energy levels,namely ^(2)H_(11/2) and ^(4)S_(3/2).of Er^(3+) ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the sample.The maximum relative sensitivity(S_(R)) is determined to be 0.0069 K^(-1) at300 K and the absolute sensitivity(S_(A)) is determined to be 0.0126 K^(-1) at 300 K.The S_(A) of self-activated KYb(MoO_(4))2:Er^(3+)is almost twice that of traditional KY(MoO_(4))2:Er^(3+)/Yb^(3+)codoping phosphor.The results demonstrate that Er^(3+) ions doped self-activated KYb(MoO_(4))2 phosphor has promising application in visible display,trademark security and optical temperature sensors.展开更多
Upconversion based nanothermometry has received much attention due to its merits of stability,narrow band emission and rich emission peaks.However,the previous works are mainly focused on the emissions from thermally ...Upconversion based nanothermometry has received much attention due to its merits of stability,narrow band emission and rich emission peaks.However,the previous works are mainly focused on the emissions from thermally coupled energy levels which is theoretically limited by Boltzmann distribution theory with resultant low temperature sensitivity in particular at ultralow temperatures.Here we report a LiYF_(4):Yb/Ho@LiYF_(4) core-shell nanostructure to improve the sensitivity at low temperatures by taking advantage of non-thermally coupled energy levels of Ho^(3+).In detail,the green upconversion emission of Ho^(3+)shows an increase with reducing temperature while its red upconversion emission presents a decline during the same process.This is primarily due to the suppression of the non-radiative multiphonon relaxation occurred at the green emitting levels(^(5)F_(4),^(5)S_(2)) and the intermediate level(^(5)I_(6)) at low temperatures.Such a feature contributes to a high relative sensitivity of 7.17%/K at 11 K,much higher than reported values.Our results provide a promising candidate for the development of nanothermometer with high-sensitive low-temperature sensing performance.展开更多
As a widespread element,heavy metals have a significant impact on human health and threaten human health.It is of great significance to develop analytical technologies that can detect heavy metal ions quickly and accu...As a widespread element,heavy metals have a significant impact on human health and threaten human health.It is of great significance to develop analytical technologies that can detect heavy metal ions quickly and accurately.In comparison to conventional fluorescent materials such as organic dyes,quantum dot(QD)labels,and carbon quantum dots(CD),fluorescence detection technology utilizing lanthanide(Ln)ion-doped upconversion nanoparticles(UCNPs)stands out due to its distinctive attributes.These include a notably reduced autofluorescence background,enhanced tissue penetration capabilities,biocompatibility with cellular tissues,and minimal photodamage inflicted on biological samples.The utilization of this technology has garnered considerable attention across multiple fields.In the domain of heavy metal detection,traditional laboratory methods necessitate costly instrumentation and a fully equipped laboratory,involving intricate sample processing procedures and protracted detection periods,as well as a demand for skilled personnel.In contrast,the implementation of this material offers rapid and cost-effective detection,significantly mitigating the technical barriers for operators.Consequently,this represents an exceptional avenue to curtail expenses and broaden the scope of detection within the analytical process.This paper reviews the research progress of UCNPs in the detection of heavy metal ions,encompassing a brief elucidation of the luminescence principle of upconversion nanomaterials and commonly used detection principles.Additionally,it provides a detailed overview of the research status of several common non-metal ions and essential heavy metals.Furthermore,it summarizes the current focal points in UCNP detection and discusses the challenges and prospects associated with it.展开更多
Sensitive mid-infrared(MIR)detection is in high demand in various applications,ranging from remote sensing,infrared surveillance,and environmental monitoring to industrial inspection.Among others,upconversion infrared...Sensitive mid-infrared(MIR)detection is in high demand in various applications,ranging from remote sensing,infrared surveillance,and environmental monitoring to industrial inspection.Among others,upconversion infrared detectors have recently attracted increasing attention due to their advantageous features of high sensitivity,fast response,and room-temperature operation.However,it remains challenging to realize high-performance passive MIR sensing due to the stringent requirement of high-power continuouswave pumping.Here,we propose and implement a high-efficiency and low-noise MIR upconversion detection system based on pumping enhancement via a low-loss optical cavity.Specifically,a singlelongitudinal-mode pump at 1064 nm is significantly enhanced by a factor of 36,thus allowing for a peak conversion efficiency of up to 22%at an intracavity average power of 55 W.The corresponding noise equivalent power is achieved as low as 0.3 fW∕Hz^(1∕2),which indicates at least a 10-fold improvement over previous results.Notably,the involved single-frequency pumping would facilitate high-fidelity spectral mapping,which is particularly attractive for high-precision MIR upconversion spectroscopy in photonstarved scenarios.展开更多
Luminescent materials that can be reversibly switched by electric field stimulation are attractive since the potential application for optoelectronic devices.Here we report a triplet-triplet annihilation upconversion(...Luminescent materials that can be reversibly switched by electric field stimulation are attractive since the potential application for optoelectronic devices.Here we report a triplet-triplet annihilation upconversion(TTA-UC)system with electrophoretic response which is developed as the electrophoretic ink.The TTA-UC system consists of an ionic derivative of 9,10-diphenyl anthracene(DPA)as the annihilator and Pt(II)octaethylporphyrin(PtOEP)as the sensitizer.Upon applying an electric field,migration and enrichment of positively charged DPA derivatives towards the cathode results in a 20%enhancement of TTA-UC.A quasi-solid film for electrically writing is made using the electrophoretic TTA system as the ink and a platinum electrode as a pen.The prototype of TTA-UC ink demonstrates unique luminescence functions upon electrically writing and erasing,providing a promising strategy to develop electronic devices for display,information storage and encryption.展开更多
Doping of rare earth elements into Bi_(4)Ti_(3)O_(12) can significantly enhance the upconversion photoluminescence(UCPL)properties,but its structure-property relationship is still unclear.In this work,Er-doped bismuth...Doping of rare earth elements into Bi_(4)Ti_(3)O_(12) can significantly enhance the upconversion photoluminescence(UCPL)properties,but its structure-property relationship is still unclear.In this work,Er-doped bismuth titanate Bi_(4-x)Er_(x)Ti_(3)O_(12)(x=0,0.1,0.2,0.3,0.4,0.5)ceramics were synthesized via solid-state reaction method.The x-ray diffraction analysis confirmed the orthorhombic crystalline structure of the Bi4-xErxTi_(3)O_(12) ceramics without any secondary phases.Experiments and calculations of positron annihilation spectroscopy were carried out to characterize their defect structure.The comparison between the experimental and calculated lifetime revealed that vacancy clusters were the main defects in the ceramics.The increase of the intensity of the second positron lifetime component(I_(2))of Bi_(3.5)Er_(0.5)Ti_(3)O_(12)ceramics indicated the presence of a high concentration of vacancy clusters.The UCPL spectra showed the sudden enhanced UCPL performance in Bi3.7Er0.3Ti3O12and Bi_(3.5)Er_(0.5)Ti_(3)O_(12)ceramics,which were consistent with the variation of the second positron lifetime component(I2).These results indicate that the enhanced UCPL properties are influenced not only by the concentrations of rare earth ions but also by the concentration of vacancy clusters present within the ceramics.展开更多
Eu^(2+)-doped Na_(3)Sc_(2)(PO_(4))_(3)ionic conductor possesses superior thermal quenching(TQ)resistance,which is considered as a promising phosphor for high-power lighting applications.Yet the underlying mechanism of...Eu^(2+)-doped Na_(3)Sc_(2)(PO_(4))_(3)ionic conductor possesses superior thermal quenching(TQ)resistance,which is considered as a promising phosphor for high-power lighting applications.Yet the underlying mechanism of negative thermal quenching(NTQ)is not fully understood.In this study,we focus on upconversion(UC)and downshifting(DS)luminescence of Yb^(3+)/Er^(3+)with f-f transition rather than susceptible d-f transition of Eu^(2+)in Na_(3)Sc_(2)(PO_(4))_(3),aiming to get a more insightful view.The results show that thermally accelerated dynamic defects/ions contributes to the significant negative thermal quenching(NTQ)of UC luminescence and thermally stabilized DS luminescence by promoting the radiative transition and suppressing the non-radiative transition.The UC process with slow population rate is more susceptible to perturbation of Na+migration process with time scale equivalent to that of the former,resulting in evident NTQ of UC luminescence.This research opens an avenue for understanding the NTQ mechanism of luminescence via dynamic defects/ions.展开更多
Photosensitizers constitute a crucial element in the process of triplet-triplet annihilation upconversion,necessitating robust absorption of visible or near-infrared light,high intersystem crossing efficiency,prolonge...Photosensitizers constitute a crucial element in the process of triplet-triplet annihilation upconversion,necessitating robust absorption of visible or near-infrared light,high intersystem crossing efficiency,prolonged triplet state lifetime,and minimal energy dissipation during intersystem crossing and vibrational relaxation.Nonetheless,conventional monomeric photosensitizers frequently fail to simultaneously meet these requirements.In recent years,researchers,including our group,have fabricated photosensitizers that incorporate multiple covalent linkages,such as dyads and triads,which are regarded more likely to achieve comprehensive performance optimization.This review article explores the design and characteristics of recently synthesized dyads and triads photosensitizers that operate on the principles of intramolecular singlet energy transfer and intramolecular triplet energy transfer,demonstrating their outstanding efficacy in high-efficiency triplet-triplet annihilation upconversion.We provide an exhaustive explanation of the design rationales,photophysical,and photochemical properties of these photosensitizers,along with suggestions for the creation of photosensitizers with enhanced performance.Moreover,we discuss potential avenues and opportunities for the future development of triplet-triplet annihilation upconversion technology.展开更多
Lutetium oxide nanocrystals codoped with Tm3＋ and Yb3＋ were synthesized by the reverse-like co-precipitation method, using ammonium hydrogen carbonate as precipitant. Effects of the Tm3＋, Yb3＋ molar fractions and ...Lutetium oxide nanocrystals codoped with Tm3＋ and Yb3＋ were synthesized by the reverse-like co-precipitation method, using ammonium hydrogen carbonate as precipitant. Effects of the Tm3＋, Yb3＋ molar fractions and calcination temperature on the structural and upconversion luminescent properties of the Lu2O3 nanocrystals were investigated. The XRD results show that all the prepared nanocrystals can be readily indexed to pure cubic phase of Lu2O3 and indicate good crystallinity. The experimental results show that concentration quenching occurs when the mole fraction of Tm3＋ is above 0.2%. The optimal Tm3＋ and Yb3＋ doped molar fractions are 0.2% and 2%, respectively. The strong blue （490 nm） and the weak red （653 nm） emissions from the prepared nanocrystals were observed under 980 nm laser excitation, and attributed to the 1G4→3H6 and IG4→3F4 transitions of Tm3＋, respectively. Power-dependent study reveals that the 1G4 levels of Tm3＋ can be populated by three-step energy transfer process. The upconversion emission intensities of 490 nm and 653 nm increase gradually with the increase of calcination temperature. The enhancement of the upconversion luminescence is suggested to be the consequence of reducing number of OH- groups and the enlarged nanoerystal size.展开更多
Flexible narrowband near infrared(NIR)photodetectors(PDs)are urgently in demand in the fastdeveloping era of flexible electronics,due to their crucial roles in various innovative applications.Hence,we designed and syn...Flexible narrowband near infrared(NIR)photodetectors(PDs)are urgently in demand in the fastdeveloping era of flexible electronics,due to their crucial roles in various innovative applications.Hence,we designed and synthesized the core-shell structured NaYF4:Yb^(3+),Er^(3+)@NaYF4:Nd^(3+)upconversion nanoparticles(UCNPs),which can be pumped by the 808 and 980 nm lights.The upconversion luminescence(UCL)are significantly enhanced after being assembled with the opal photonic crystals(OPCs)due to the photonic crystal effect,with 55 and 48 folds of enhancement factors under illuminations of 808 and 980 nm lights,respectively.Based on this hybrid,the flexible narrowband PDs were successfully fabricated on the PET substrate with the structure of OPCs/NaYF4:Yb^(3+),Er^(3+)@Nd^(3+)/MAPbl3,which displays excellent detection performance to double narrowband NIR light(808 and 980 nm)benefiting from the amplified UCL,with responsivity of 8.79 and 7.39 A/W,detectivity of 3.01×10^(11)and2.68×10^(11)cm·Hz^(1/2)/W for 808 and 980 nm lights detection respectively,along with short response time in the range of 120-160 ms.Furthermore,the OPCs/NaYF4:Yb^(3+),Er^(3+)@NaYF4:Nd^(3+)/MAPbI3 double narrowband PDs display low photodetection power threshold(0.05 W/cm2),outstanding flexibility,prominent moisture resistance,and good long-time stability.This work displays a new concept of narrowband NIR PDs,which open a new field for specific NIR light detections.展开更多
In this paper, the Au nanoparticles and rare-earth （RE） upconversion nanoparticles （NPs） were respectively synthesized by using polyelectrolyte as the capping agents. Since the synthesized Au NPs and RE NPs had th...In this paper, the Au nanoparticles and rare-earth （RE） upconversion nanoparticles （NPs） were respectively synthesized by using polyelectrolyte as the capping agents. Since the synthesized Au NPs and RE NPs had the similar size and surface conditions, Their mixture were employed in a pH sensing application. Benefited from the good spectral overlap between the RE upconversion emission bands and pH-tunable surface plasmon bands of the Au NPs, the pH-induced manipulation of green-to-red emission intensity ratio of the upconversion fluorescence was achieved in the Au-RE mixture. The results demonstrate a rapid ratiometric approach for pH sensing, which is more efficient than traditional sensing methods that depend on single intensity-based responses to analytes.展开更多
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),"Qinglan Project"Young and Middle-aged Academic Leaders Program of Jiangsu Province,and the National Natural Science Foundation of China(General Program).
文摘The enhancement of the intensity of red upconversion(UC)emission has significant implications for biological applications.In KZnF_(3):Yb^(3+),Er^(3+)which inherently produces high-purity red emission,the introduction of Fe^(3+)markedly improves the UC intensity by a factor of 13.The mechanism behind the enhanced UC red luminescence is deduced to originate from the Yb^(3+)-Fe^(3+)dimer,as determined by first principle calculation and analysis of UC luminescence properties.The thermometry performance,based on splitting peaks of red emission,demonstrated enhanced temperature sensitivity at lower ranges.Exploring the photothermal properties,it was observed that temperature exhibited a linear correlation with pump power under a 980 nm laser,achieving levels up to 48℃.This temperature range is ideal for applications in mild photothermal therapy(MPTT).This work elucidates the material’s potential in advanced biological applications,merging optical thermometry and photothermics,indicating its multifunctional utility.
文摘4-Nonylphenol(NP)is a kind of estrogen belonging to the endocrine disrupter,widely used in various agricultural and industrial goods.However,extensive use of NP with direct release to environment poses high risks to both human health and ecosystems.Herein,for the first time,we developed near-infrared(NIR)responsive upconversion luminescence nanosensor for NP detection.The Förster resonance energy transfer based upconversion nanoparticles(UCNPs)-graphene oxide sensor offers highly selective and sensitive detection of NP in linear ranges of 5−200 ng/mL and 200−1000 ng/mL under 980 nm and 808 nm excitation,respectively,with LOD at 4.2 ng/mL.The sensors were successfully tested for NP detection in real liquid milk samples with excellent recovery results.The rare-earth fluoride based upconversion luminescence nanosensor with NIR excitation wavelength,holds promise for sensing food,environmental,and biological samples due to their high sensitivity,specific recognition,low LOD,negligible autofluorescence,along with the deep penetration of NIR excitation sources.
基金Project supported by the National Natural Science Foundation of China(62105235,62205035)the Scientific Research Project of Tianjin Education Commission(2022KJ060)+1 种基金Qinglan Project of Jiangsu Province of ChinaNatural Science Foundation of the Jiangsu Higher Education Institutions of China(22KJD350001)。
文摘Very recently,upconversion luminescence(UCL)lifetime,as a powerful optical dimension,has attracted tremendous research interest due to its advantages of high information capacity and high photophysical stability.With the implementation and emergence of endlessly fascinating UCL features,it is particularly meaningful to understand the photophysical mechanisms inside UCL materials to enable rational subdivision-level structure design,which is however currently far from sufficient.In this work,we take an ordinary upconversion nanoparticle as an example to prove that the UCL decay curves and corresponding lifetimes are indeed a collective response of the entire UCL system to excitations,that exhibits correlated,yet quite different properties from individual ions.A specially developed theoretical random walk model combined with an experimental lifetime control for Yb^(3+)/Er^(3+)UCL demonstrates that ene rgy diffusion principally alters the decay rate.Moreover,the different extent of the influence of energy diffusion on the emissions of ^(2)H_(11/2)/^(4)S_(3/2)(green)and ^(4)F_(9/2)(red)leads to an extremely uncommon crossover comparison of decay rates.This work provides new ideas for understanding decay dynamics and practical UCL lifetime manipulation methods.
基金supported by the National Natural Science Foundation of China(51701091,12004148,12104199,12204216)the Natural Science Foundation of Shandong Province(ZR2021QA057)+1 种基金the Shandong Province Science and Technology Small and Medium Sized Enterprise Innovation Ability Enhancement Project(2023TSGC0352)the Innovation Team of Higher Educational Science and Technology Program of Shandong Province(2019KJA025)。
文摘Ultraviolet upconversion photoluminescence materials have great potential in various fields,but the improvement of the upconversion efficiency is challenging.Codoping of Li^(+)is considered as an effective strategy and widely used to improve the photoluminescence properties of phosphors.In this paper,Li^(+)is introduced into a Y_(7)O_(6)F_(9):Pr^(3+),Gd^(3+)system.The effect of Li^(+)codoping on the phase purity,crystal structure,micro structure,downshifting and upconversion photo luminescence as well as the decay dynamic of the phosphors was studied.It is revealed that the overall photoluminescence efficiency and the energy transfer efficiency from pr^(3+)to Gd^(3+)are greatly promoted.The downshifting and upconversion photoluminescence increase by 2.58 and 10 times as 6 mol%of Li^(+)is codoped.The photo luminescence decay dynamic study shows that the ^(3)P_(0)state decays slower in the Li^(+)-containing phosphor than the Li^(+)-free one.The improvement of the photoluminescence properties is due to the increase of the crystallinity and the reduce of the quenching center.
基金supported by Senior Talent Fund of Jiangsu University(No.5501310021)China Postdoctoral Science Foundation(No.2023M741419)+1 种基金the Young Elite Scientist Sponsorship Program by ZJAST(No.G301310002)Research Fund for International Scientists(No.22350710187).
文摘Lanthanide-sensitized upconverting nanoparticles(UCNPs)are widely studied because of their unusual optical characteristics,such as large antenna-generated anti-Stokes shifts,high photostability,and narrow emission bandwidths,which can be harnessed for a variety of applications including bioimaging,sensing,information security and high-level anticounterfeiting.The diverse requirements of these applications typically require precise control over upconversion luminescence(UCL).Recently,the concept of energy migration upconversion has emerged as an effective approach to modulate UCL for various lanthanide ions.Moreover,it provides valuable insights into the fundamental comprehension of energy transfer mechanisms on the nanoscale,thereby contributing to the design of efficient lanthanide-sensitized UCNPs and their practical applications.Here we present a comprehensive overview of the latest developments in energy migration upconversion in lanthanide-sensitized nanoparticles for photon upconversion tuning,encompassing design strategies,mechanistic investigations and applications.Additionally,some future prospects in the field of energy migration upconversion are also discussed.
基金Project supported by National Natural Science Foundation of China(62305244,62374112,62105078)Shandong Province Natural Science Foundation(ZR2021QE060,ZR2021QF009)+1 种基金Young Elite Scientists Sponsorship Program by China Association for Science and Technology(2022QNRC001)Youth Science and Technology Innovation Team of Shandong Province Institution of Higher Learning(2022KJ258)。
文摘In this work,rare earth ions(REs)including Yb^(3+)/Er^(3+),Yb^(3+)/Ho^(3+)and Yb^(3+)/Tm^(3+)co-doped manganese oxyfluoride glasses were fabricated using melt quenching method.By fully utilizing the upconversion luminescence(UCL)of REs and regulating energy transfer between the different energy levels of RE ions and the4T1level of Mn^(2+),the output of UCL was regulated and even pure-red light can be achieved.Moreover,owing to the selective partitioning caused by phase-separation network structure in the oxyfluoride glass,the UCL intensity of glasses annealed for 72 h is significantly enhanced 58 times compared to the rapidly quenched samples.
基金financially supported by the National Natural Science Foundation of China(No.21871122)。
文摘Organic afterglow materials hold significant potential for applications in information storage,anticounterfeiting,and biological imaging.However,studies on afterglow materials capable of ultra-wide range excitation and emission simultaneously are limited.To enhance the practicality of strong emission single-component organic afterglow systems,overcoming the constraints of crystalline or other rigid environments is essential.We have developed solid-state dual-persistent thermally activated delayed fluorescence(TADF)and room temperature phosphorescence(RTP)emissions spanning yellow to red under visible light excitation,utilizing a single-molecule terminal group regulation strategy.The RTP lifetime extends from 4.19 ms to 399.70 ms.These afterglow materials exhibit an ultra-wide absorption range from 200 nm to 800 nm,rendering them capable of being excited by both sunlight simulator and nearinfrared radiation.The upconversion phosphorescence lifetime under 808 nm excitation reaches 13.72μs.The double persistent emission of these compounds is temperature-sensitive.Moreover,following grinding or heat treatment,accompanied by extensive afterglow color conversion due to planarization of excited state conformations and additional efficient kRIsc generation.In addition,the amorphous state post melt annealing facilitates the afterglow transition from yellow to green.Crucially,these compounds also maintain stable ultra-long afterglow emission in aqueous and acid-base environments.Overall,we have successfully developed a series of single-component intelligent luminescent materials that demonstrate significant benefits,including dual TADF and RTP emissions,adjustable afterglow lifetimes,a broad range of excitation and emission wavelengths,multi-modal luminescence not restricted to crystalline states,and robust afterglow performance in challenging environments,setting the stage for the practical deployment of afterglow materials in engineering applications,the upconversion afterglow emission also holds promising potential for applications in the field of biological imaging.
基金financially supported by the National Natural Science Foundation of China(Nos.11704081,52125205,52250398,U20A20166,52192614 and 52003101)Guangxi Natural Science Foundation(Nos.2020GXNSFAA297182,2020GXNSFAA297041 and 2017GXNSFBA19-8229)+5 种基金the special fund for Guangxi Bagui ScholarsNational Science and Technology Innovation Talent Cultivation Program(No.2023BZRC016)National Key R&D Program of China(Nos.2021YFB3200302 and2021YFB3200304)the Natural Science Foundation of Beijing Municipality(No.2222088)Shenzhen Science and Technology Innovation Program(No.KQTD20170810105439418)the Fundamental Research Funds for the Central Universities。
文摘Polarization upconversion luminescence(PUCL)of lanthanide ions(Ln^(3+))has been widely used in single particle tracking,microfluidics detection,three-dimensional displays,and so on.However,no effective strategy has been developed for modulating PUCL.Here we report a strategy to regulate PUCL in Ho^(3+)-doped NaYF4single nanorods based on the number of upconversion photons.By constructing a multiphoton upconversion system for Ho^(3+),we regulate the degree of polarization(DOP)of PUCL from 0.590 for two-photon luminescence to 0.929 for three-photon upconversion luminescence(UCL).Furthermore,our strategy is verified from cross-relaxation between Ho^(3+)and Yb^(3+),excitation wavelength,excitation power density,and local site symmetry.And this regulation strategy of PUCL has also been achieved in Tm^(3+),with the DOP ranging from 0.233 for two-photon luminescence to 0.925 for four-photon UCL Besides,multi-dimensional anti-counterfeiting display has been explored with PUCL.This work provides an effective strategy for regulating PUCL and also provides more opportunities for the development of polarization display optical encoding,anti-counterfeiting,and integrated optical devices.
基金Project supported by the National Key R&D Program of China(2020YFA0709900)the National Natural Science Foundation of China(52072172,22105098)。
文摘Heavily doped upconversion nanoparticles(UCNPs)potentially have exceptional photon upconversion abilities that are promising for diverse applications,such as lasing and super-resolution microscopy.However,heavily doped UCNPs typically can only offer mediocre upconversion luminescence intensity,and there still lacks general guidelines for the design and synthesis of heavily doped UCNPs.Herein,in order to boost the upconversion luminescence of heavily doped UCNPs,we studied the influence of characteristics of the core-shell structure on heavily doped UCNPs'upconversion luminescence.We find that some empirical guidelines derived from conventional UCNPs are not suitable for heavily doped UCNPs.Using NaYbF_(4):Tm@NaYF_(4) core-shell UCNPs with a high concentration of Yb_(3+)as a representative,our studies reveal that a rather thick inert NaYF4 shell is needed to protect the UCNPs from surface quenching,and the upconversion luminescence may undergo the cooperative sensitization process,which should be due to the highly concentrated Yb~(3+)dopant.In addition,the upconversion luminescence of heavily doped NaYbF4:Tm UCNPs exhibits no obvious dependence on the type of inert shell.Furthermore,our results show that confining both Yb~(3+)and Tm~(3+)dopants in a thin layer(known as theδ-doping strategy)does not work well in the heavily doped UCNPs.Accordingly,we propose a NaYbF_(4):Tm@NaYbF_(4)@NaYF_(4) core-shell-shell structure to enhance the luminescence of heavily doped UCNPs,by weakening the dissipation of excitation energy and strengthening the absorption.These findings should be helpful to establish general design principles for developing the brightest possible UCNPs that can meet the requirements of various applications.
基金supported by the National Natural Science Foundation of China (52202001)Open Project of Advanced Laser Technology Laboratory of Anhui Province (AHL2021KF07)+1 种基金Major Science and Technology of Anhui Province(202203a05020002)University Natural Science Research Project of Anhui Province (KJ2021A0388)。
文摘In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as-prepared samples was analyzed by X-ray diffraction(XRD),XRD Rietveld refinement and Fourier transform infrared(FT-IR) spectroscopy.The as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er^(3+) doping concentration up to 15 at%.High-purity upconversion(UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er^(3+) ions in the self-activated KYb(MoO_(4))_(2) host is revealed as 3 at%.The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC spectra.In addition,the fluorescence intensity ratios(FIRs) of the two thermally-coupled energy levels,namely ^(2)H_(11/2) and ^(4)S_(3/2).of Er^(3+) ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the sample.The maximum relative sensitivity(S_(R)) is determined to be 0.0069 K^(-1) at300 K and the absolute sensitivity(S_(A)) is determined to be 0.0126 K^(-1) at 300 K.The S_(A) of self-activated KYb(MoO_(4))2:Er^(3+)is almost twice that of traditional KY(MoO_(4))2:Er^(3+)/Yb^(3+)codoping phosphor.The results demonstrate that Er^(3+) ions doped self-activated KYb(MoO_(4))2 phosphor has promising application in visible display,trademark security and optical temperature sensors.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.51972119 and 52272151)the Fundamental Research Funds for the Central Universities (2022ZYGXZR015)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01X137)。
文摘Upconversion based nanothermometry has received much attention due to its merits of stability,narrow band emission and rich emission peaks.However,the previous works are mainly focused on the emissions from thermally coupled energy levels which is theoretically limited by Boltzmann distribution theory with resultant low temperature sensitivity in particular at ultralow temperatures.Here we report a LiYF_(4):Yb/Ho@LiYF_(4) core-shell nanostructure to improve the sensitivity at low temperatures by taking advantage of non-thermally coupled energy levels of Ho^(3+).In detail,the green upconversion emission of Ho^(3+)shows an increase with reducing temperature while its red upconversion emission presents a decline during the same process.This is primarily due to the suppression of the non-radiative multiphonon relaxation occurred at the green emitting levels(^(5)F_(4),^(5)S_(2)) and the intermediate level(^(5)I_(6)) at low temperatures.Such a feature contributes to a high relative sensitivity of 7.17%/K at 11 K,much higher than reported values.Our results provide a promising candidate for the development of nanothermometer with high-sensitive low-temperature sensing performance.
基金supported by the Science and Technology Development Fund,Macao SAR(Grant 0065/2023/ITP2).
文摘As a widespread element,heavy metals have a significant impact on human health and threaten human health.It is of great significance to develop analytical technologies that can detect heavy metal ions quickly and accurately.In comparison to conventional fluorescent materials such as organic dyes,quantum dot(QD)labels,and carbon quantum dots(CD),fluorescence detection technology utilizing lanthanide(Ln)ion-doped upconversion nanoparticles(UCNPs)stands out due to its distinctive attributes.These include a notably reduced autofluorescence background,enhanced tissue penetration capabilities,biocompatibility with cellular tissues,and minimal photodamage inflicted on biological samples.The utilization of this technology has garnered considerable attention across multiple fields.In the domain of heavy metal detection,traditional laboratory methods necessitate costly instrumentation and a fully equipped laboratory,involving intricate sample processing procedures and protracted detection periods,as well as a demand for skilled personnel.In contrast,the implementation of this material offers rapid and cost-effective detection,significantly mitigating the technical barriers for operators.Consequently,this represents an exceptional avenue to curtail expenses and broaden the scope of detection within the analytical process.This paper reviews the research progress of UCNPs in the detection of heavy metal ions,encompassing a brief elucidation of the luminescence principle of upconversion nanomaterials and commonly used detection principles.Additionally,it provides a detailed overview of the research status of several common non-metal ions and essential heavy metals.Furthermore,it summarizes the current focal points in UCNP detection and discusses the challenges and prospects associated with it.
基金supported by the National Key Research and Development Program(Grant No.2021YFB2801100)the National Natural Science Foundation of China(Grant Nos.62175064,62235019,62035005,and 12022411)+3 种基金the Shanghai Pilot Program for Basic Research(Grant No.TQ20220104)the Natural Science Foundation of Chongqing(Grant Nos.CSTB2023NSCQ-JQX0011,CSTB2022NSCQ-MSX0451,and CSTB2022NSCQ-JQX0016)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)the Fundamental Research Funds for the Central Universities.
文摘Sensitive mid-infrared(MIR)detection is in high demand in various applications,ranging from remote sensing,infrared surveillance,and environmental monitoring to industrial inspection.Among others,upconversion infrared detectors have recently attracted increasing attention due to their advantageous features of high sensitivity,fast response,and room-temperature operation.However,it remains challenging to realize high-performance passive MIR sensing due to the stringent requirement of high-power continuouswave pumping.Here,we propose and implement a high-efficiency and low-noise MIR upconversion detection system based on pumping enhancement via a low-loss optical cavity.Specifically,a singlelongitudinal-mode pump at 1064 nm is significantly enhanced by a factor of 36,thus allowing for a peak conversion efficiency of up to 22%at an intracavity average power of 55 W.The corresponding noise equivalent power is achieved as low as 0.3 fW∕Hz^(1∕2),which indicates at least a 10-fold improvement over previous results.Notably,the involved single-frequency pumping would facilitate high-fidelity spectral mapping,which is particularly attractive for high-precision MIR upconversion spectroscopy in photonstarved scenarios.
基金the financial support from the National Natural Science Foundation of China(Nos.22273117,22273110 and 22090012)。
文摘Luminescent materials that can be reversibly switched by electric field stimulation are attractive since the potential application for optoelectronic devices.Here we report a triplet-triplet annihilation upconversion(TTA-UC)system with electrophoretic response which is developed as the electrophoretic ink.The TTA-UC system consists of an ionic derivative of 9,10-diphenyl anthracene(DPA)as the annihilator and Pt(II)octaethylporphyrin(PtOEP)as the sensitizer.Upon applying an electric field,migration and enrichment of positively charged DPA derivatives towards the cathode results in a 20%enhancement of TTA-UC.A quasi-solid film for electrically writing is made using the electrophoretic TTA system as the ink and a platinum electrode as a pen.The prototype of TTA-UC ink demonstrates unique luminescence functions upon electrically writing and erasing,providing a promising strategy to develop electronic devices for display,information storage and encryption.
基金Project supported by the National Key Research and Development Program of China(Grant No.2019YFA0210000)the National Natural Science Foundation of China(Grant No.12175232)。
文摘Doping of rare earth elements into Bi_(4)Ti_(3)O_(12) can significantly enhance the upconversion photoluminescence(UCPL)properties,but its structure-property relationship is still unclear.In this work,Er-doped bismuth titanate Bi_(4-x)Er_(x)Ti_(3)O_(12)(x=0,0.1,0.2,0.3,0.4,0.5)ceramics were synthesized via solid-state reaction method.The x-ray diffraction analysis confirmed the orthorhombic crystalline structure of the Bi4-xErxTi_(3)O_(12) ceramics without any secondary phases.Experiments and calculations of positron annihilation spectroscopy were carried out to characterize their defect structure.The comparison between the experimental and calculated lifetime revealed that vacancy clusters were the main defects in the ceramics.The increase of the intensity of the second positron lifetime component(I_(2))of Bi_(3.5)Er_(0.5)Ti_(3)O_(12)ceramics indicated the presence of a high concentration of vacancy clusters.The UCPL spectra showed the sudden enhanced UCPL performance in Bi3.7Er0.3Ti3O12and Bi_(3.5)Er_(0.5)Ti_(3)O_(12)ceramics,which were consistent with the variation of the second positron lifetime component(I2).These results indicate that the enhanced UCPL properties are influenced not only by the concentrations of rare earth ions but also by the concentration of vacancy clusters present within the ceramics.
文摘Eu^(2+)-doped Na_(3)Sc_(2)(PO_(4))_(3)ionic conductor possesses superior thermal quenching(TQ)resistance,which is considered as a promising phosphor for high-power lighting applications.Yet the underlying mechanism of negative thermal quenching(NTQ)is not fully understood.In this study,we focus on upconversion(UC)and downshifting(DS)luminescence of Yb^(3+)/Er^(3+)with f-f transition rather than susceptible d-f transition of Eu^(2+)in Na_(3)Sc_(2)(PO_(4))_(3),aiming to get a more insightful view.The results show that thermally accelerated dynamic defects/ions contributes to the significant negative thermal quenching(NTQ)of UC luminescence and thermally stabilized DS luminescence by promoting the radiative transition and suppressing the non-radiative transition.The UC process with slow population rate is more susceptible to perturbation of Na+migration process with time scale equivalent to that of the former,resulting in evident NTQ of UC luminescence.This research opens an avenue for understanding the NTQ mechanism of luminescence via dynamic defects/ions.
基金supported by the National Natural Science Foundation of China(No.22203004 and No.21927814)the Anhui Normal University 2023 Scholarship and Supplementary Discipline Construction Project(No.2023GFXK160).
文摘Photosensitizers constitute a crucial element in the process of triplet-triplet annihilation upconversion,necessitating robust absorption of visible or near-infrared light,high intersystem crossing efficiency,prolonged triplet state lifetime,and minimal energy dissipation during intersystem crossing and vibrational relaxation.Nonetheless,conventional monomeric photosensitizers frequently fail to simultaneously meet these requirements.In recent years,researchers,including our group,have fabricated photosensitizers that incorporate multiple covalent linkages,such as dyads and triads,which are regarded more likely to achieve comprehensive performance optimization.This review article explores the design and characteristics of recently synthesized dyads and triads photosensitizers that operate on the principles of intramolecular singlet energy transfer and intramolecular triplet energy transfer,demonstrating their outstanding efficacy in high-efficiency triplet-triplet annihilation upconversion.We provide an exhaustive explanation of the design rationales,photophysical,and photochemical properties of these photosensitizers,along with suggestions for the creation of photosensitizers with enhanced performance.Moreover,we discuss potential avenues and opportunities for the future development of triplet-triplet annihilation upconversion technology.
基金Foundation item: Projects (10704090,10774140,11047147)supported by the National Natural Science Foundation of ChinaProjects (KJ090514,KJTD201016)supported by the Natural Science Foundation of Chongqing Municipal Education Commission,China
文摘Lutetium oxide nanocrystals codoped with Tm3＋ and Yb3＋ were synthesized by the reverse-like co-precipitation method, using ammonium hydrogen carbonate as precipitant. Effects of the Tm3＋, Yb3＋ molar fractions and calcination temperature on the structural and upconversion luminescent properties of the Lu2O3 nanocrystals were investigated. The XRD results show that all the prepared nanocrystals can be readily indexed to pure cubic phase of Lu2O3 and indicate good crystallinity. The experimental results show that concentration quenching occurs when the mole fraction of Tm3＋ is above 0.2%. The optimal Tm3＋ and Yb3＋ doped molar fractions are 0.2% and 2%, respectively. The strong blue （490 nm） and the weak red （653 nm） emissions from the prepared nanocrystals were observed under 980 nm laser excitation, and attributed to the 1G4→3H6 and IG4→3F4 transitions of Tm3＋, respectively. Power-dependent study reveals that the 1G4 levels of Tm3＋ can be populated by three-step energy transfer process. The upconversion emission intensities of 490 nm and 653 nm increase gradually with the increase of calcination temperature. The enhancement of the upconversion luminescence is suggested to be the consequence of reducing number of OH- groups and the enlarged nanoerystal size.
基金Project supported by the National Natural Science Foundation of China(11974143,11874181,61822506,U1801253,11904124)the Special Project of the Province-University Co-constructing Program of Jilin Province(SXGJXX2017-3)。
文摘Flexible narrowband near infrared(NIR)photodetectors(PDs)are urgently in demand in the fastdeveloping era of flexible electronics,due to their crucial roles in various innovative applications.Hence,we designed and synthesized the core-shell structured NaYF4:Yb^(3+),Er^(3+)@NaYF4:Nd^(3+)upconversion nanoparticles(UCNPs),which can be pumped by the 808 and 980 nm lights.The upconversion luminescence(UCL)are significantly enhanced after being assembled with the opal photonic crystals(OPCs)due to the photonic crystal effect,with 55 and 48 folds of enhancement factors under illuminations of 808 and 980 nm lights,respectively.Based on this hybrid,the flexible narrowband PDs were successfully fabricated on the PET substrate with the structure of OPCs/NaYF4:Yb^(3+),Er^(3+)@Nd^(3+)/MAPbl3,which displays excellent detection performance to double narrowband NIR light(808 and 980 nm)benefiting from the amplified UCL,with responsivity of 8.79 and 7.39 A/W,detectivity of 3.01×10^(11)and2.68×10^(11)cm·Hz^(1/2)/W for 808 and 980 nm lights detection respectively,along with short response time in the range of 120-160 ms.Furthermore,the OPCs/NaYF4:Yb^(3+),Er^(3+)@NaYF4:Nd^(3+)/MAPbI3 double narrowband PDs display low photodetection power threshold(0.05 W/cm2),outstanding flexibility,prominent moisture resistance,and good long-time stability.This work displays a new concept of narrowband NIR PDs,which open a new field for specific NIR light detections.
基金Supported by grants from the Natural Science Foundation of Jiangsu Province(SBK201240182)the Natural Science Foundation of China(J1210061)
文摘In this paper, the Au nanoparticles and rare-earth （RE） upconversion nanoparticles （NPs） were respectively synthesized by using polyelectrolyte as the capping agents. Since the synthesized Au NPs and RE NPs had the similar size and surface conditions, Their mixture were employed in a pH sensing application. Benefited from the good spectral overlap between the RE upconversion emission bands and pH-tunable surface plasmon bands of the Au NPs, the pH-induced manipulation of green-to-red emission intensity ratio of the upconversion fluorescence was achieved in the Au-RE mixture. The results demonstrate a rapid ratiometric approach for pH sensing, which is more efficient than traditional sensing methods that depend on single intensity-based responses to analytes.
