A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^...A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^3+ samples showed broad excitation spectrum from 250 to 400 nm and presented characteristic emission transitions ^5D4→^7FJ(J=6, 5, 4, 3) of Tb^3+ under 313 nm excitation, which were located at about 488, 541, 584 and 620 nm. The emission intensities of Tb^3+ rose steadily in Sr3Gd2(Si3O9)2 host with the increase of Tb^3+ concentration even though Gd^3+ ions were completely replaced by Tb^3+ ions. The Ce^3+ ion as a sensitizer could efficiently improve the performance of Tb^3+ ion. First, with Ce^3+ co-doping, the excitation spectrum of Tb^3+ monitored at 541 nm showed a similar band that responds to the violet emission of Ce^3+ monitored at 416 nm. Second, the quantum yields of Sr3Gd2(Si3O9)2:Tb^3+ phosphors could be enhanced from 26.6% to 80.2% by co-doping Ce^3+. Finally, the co-doping of Ce^3+ was also effective to improve the thermal stability of Sr3Gd2(Si3O9)2:Tb^3+. As the temperature rose to 150 oC, the emission intensity of Tb^3+ remained at about 83.6% of that measured at room temperature, which was better than the commercial YAG:Ce phosphor in terms of their thermal quenching properties. These results indicated that the as-prepared Sr3Gd2(Si3O9)2:Tb^3+,Ce^3+ samples could be used as green emission phosphors for possible applications in near ultraviolet based WLEDs.展开更多
The major cytotoxic agent with most current photosensitizers used in photodynamic therapy(PDT)is widely believed to be singlet oxygen(^(1)O_(2)).Determination of the ^(1)O_(2) quantum yields for porphyrin-based photos...The major cytotoxic agent with most current photosensitizers used in photodynamic therapy(PDT)is widely believed to be singlet oxygen(^(1)O_(2)).Determination of the ^(1)O_(2) quantum yields for porphyrin-based photosensitizers,including hematoporphyrin derivative(HiPorfin),hematoporphyrin monomethyl ether(HMME)and photocarcinorin(PsD-007)in air-saturated dimethylformamide(DMF)solutions were performed by the direct measurement of their near-infrared luminescence.In addition,^(1)O_(2) quencher sodium azide was employed to confirm the ^(1)O_(2) generation from the investigated photosensitizers.The maximal ^(1)O_(2) luminescence occurs at about 1280 nm with full width at half maximum of 30 nm.The ^(1)O_(2) quantum yields were found to be 0.61±0.03,0.60±0.02 and 0.59±0.03 for HiPorfin,HMME and PsD-007,respectively.These results provide that these porphyrin-based photosensitizers produce ^(1)O_(2) under irradiation,which is of significance for the study of their photodynamic action in PDT.展开更多
Theoretical dependence of the quantum yields on the size of Agnano-particle distribution from 0.8 nm to 37 nm embedded in BaOsemiconductor is discussed. The calculation results show that theincrease in Ag nano-particl...Theoretical dependence of the quantum yields on the size of Agnano-particle distribution from 0.8 nm to 37 nm embedded in BaOsemiconductor is discussed. The calculation results show that theincrease in Ag nano-particle diameter leads to the increase of thequantum yield threshold and the emergence of the rough Gaussian form,the results also shown that the greater increase in Ag nano-particlediameter causes the emergence of the exact Gaussian form and makesthe peaks rise up.展开更多
White light illumination is essential in daily life,however,the substantial amount of blue light it contains can damage human eyes.Therefore,it is important to block this high-energy blue light to protect visual healt...White light illumination is essential in daily life,however,the substantial amount of blue light it contains can damage human eyes.Therefore,it is important to block this high-energy blue light to protect visual health.In this study,yellow-emitting carbon dots(CDs)with a quantum yield exceeding 94%were synthesized using citric acid and urea.These CDs effectively absorb blue light.By incorporating them into polystyrene,multiple films termed CDs-based blue light blocking films(CBFs)were developed,each offering different levels of blue light absorption.These CBFs exhibited excellent transparency and efficient blue light filtering capabilities.This study highlights the potential of high quantum yield CDs,which specifically absorb blue light,as foundational materials for developing light-blocking solutions against highenergy short-wavelength light.展开更多
Carbon dots(CDs)with solvatochromic emission colors in different solvents have attracted much attention as a new class of luminescent nanomaterial owing to their facile synthesis and low production cost.In this work,w...Carbon dots(CDs)with solvatochromic emission colors in different solvents have attracted much attention as a new class of luminescent nanomaterial owing to their facile synthesis and low production cost.In this work,we prepared two kinds of CDs with solvatochromic emissions:green emission CDs(G-CDs)and multicolor emission CDs(M-CDs).G-CDs synthesized from o-phenylenediamine exhibited weak photoluminescence emission(quantum yield 2.8%-6.1%)and 39 nm solvatochromic shifts(492-531 nm).In contrast,M-CDs prepared from o-phenylenediamine and 4-aminophenol showed 87 nm solvatochromic shift range(505-592 nm)and much higher photoluminescence quantum yield(18.4%-32.5%).The two CDs exhibited different emission,absorption,and photoluminescence lifetime.The origin of solvatochromic shifts and the formation mechanism of CDs were demonstrated by analyzing the structures and compositions of two CDs.High percentages of pyrrolic nitrogen and amino nitrogen make wider solvatochromic shifts and higher quantum yields.The results were well supported by density functional theory calculations.This effective strategy to expand solvatochromic shift range and improve quantum yields could open a new window to prepare satisfied solvatochromic carbon dots.展开更多
Considering the toxicity problem of lead-based perovskite quantum dots(PQDs),the lead-free Cs_(3)Bi_(2)Br_(g)PQDs has been recognized as one of the promising candidates.However,the low photoluminescence quantum yields...Considering the toxicity problem of lead-based perovskite quantum dots(PQDs),the lead-free Cs_(3)Bi_(2)Br_(g)PQDs has been recognized as one of the promising candidates.However,the low photoluminescence quantum yields(PLQYs)hinder its practical application in optoelectronic devices.Here,w e successfully prepared Sm^(3+)ions doped Cs_(3)Bi_(2)Br_(g)PQDs with effective white light-emission by modified ligandassisted recrystallization method.The realization of white light-emission is attributed to the broadband blue emission of excitons and the red emission(^(4)G_(5/2)-^(6)HJ(J=5/2,7/2,9/2))of Sm^(3+)ions for Sm^(3+)ions doped Cs_(3)Bi_(2)Br_(g)PQDs.More importantly,compared with the undoped Cs_(3)Bi_(2)Br_(g)PQDs,the PLQYs of Sm^(3+)ions doped Cs_(3)Bi_(2)Br_(g)PQDs are improved from 10.9%to 20.8%,and the anti-water stability is also obviously improved.Finally,the Sm^(3+)ions doped PQDs based white light-emitting diodes(LEDs)with luminous efficiency of 12.6 lm/W were explored,which indicates that there is a potential prospect of lead-free PQDs in white light lighting application.展开更多
Four benzocoumarin-based two-photon fluorescent probes(BH1-BH4)are proposed for ra-tiometric detection of hypochlorous acid(HClO)and their two-photon sensing perfor-mance are evaluated by means of time-dependent densi...Four benzocoumarin-based two-photon fluorescent probes(BH1-BH4)are proposed for ra-tiometric detection of hypochlorous acid(HClO)and their two-photon sensing perfor-mance are evaluated by means of time-dependent density func-tional theory and quadratic re-sponse theory.The effects of benzene-fused position on Stokes shift,fluorescence quantum yield and two-photon absorption are discussed comprehensively.The results show that fusing a benzene ring in coumarin can enhance Stokes shift efficiently.The benzene-fused position has important effects on these photophysical properties.The benzo[g]coumarins(BH1)and benzo[f]coumarins(BH2)derivatives have larger Stokes shifts in comparison with benzo[h]coumarins(BH3)and dihydrophenazine(BH4)derivatives.The two-photon absorp-tion of benzo[f]coumarins(BH2)derivative is much smaller than those of other benzo-coumarins derivatives.The large Stokes shift and increased two-photon action cross section can be achieved simultaneously in the dihydrophenazine(BH4)derivative.Therefore,the de-signed BH4 is expected to have superior performance for the ratiometric detection of HClO.To explore the reasons behind these effects,the intramolecular charge transfer degrees are il-lustrated quantitatively by plotting the hole-electron isosurface map,and the relation be-tween charge transfer and Stokes shift is revealed.A two-state model analysis is employed to understand two-photon absorption ability.Moreover,the fluorescence near-quenching mecha-nism of the product molecules B1 and B3 is explained by analyzing reorganization energy and Huang-Rhys factor,as well as related normal mode.Our research could contribute to the effi-cient design of ratiometric two-photon fluorescent probes with large Stokes shift and signifi-cant two-photon action cross section.展开更多
In this study,a simple and effective ratiometric fluorescence method has been developed for carbaryl detection,utilizing red emissive carbon dots(R-CDs).The underlying principle of this proposed strategy relies on the...In this study,a simple and effective ratiometric fluorescence method has been developed for carbaryl detection,utilizing red emissive carbon dots(R-CDs).The underlying principle of this proposed strategy relies on the rapid hydrolysis of carbaryl under an alkaline condition and production of 1-naphthol with blue-emission at 462 nm.Furthermore,the as-synthesized R-CDs(Em.677 nm),serve as a reference,enhancing the visual tracking of carbaryl through the transformation of fluorescent color from red to blue.The concentration of carbaryl exhibits a commendable linear correlation with the ratio of fluorescence intensity,ranging from 0 to 20μg/m L(R^(2)=0.9989)with a low detection limit of 0.52 ng/m L.Additionally,the described methodology can be used for the enzyme-free visual assay of carbaryl,even in the presence of other carbamate pesticides and metal ions,in tap water and lake water samples with excellent accuracy(spiked recoveries,94%-106.1%),high precision(relative standard deviation(RSD)≤2.42),and remarkable selectivity.This fast and highly sensitive naked-eye ratiometric sensor holds immense promise for carbaryl detection in intricate environments and food safety fields.展开更多
Mn^(2+)-doped CsPbCl_(3)(Mn^(2+):CsPbCl_(3)) nanocrystals(NCs) have attracted considerable attention due to their unique strong and broad orange-red emission band,presenting promising applications in the field of phot...Mn^(2+)-doped CsPbCl_(3)(Mn^(2+):CsPbCl_(3)) nanocrystals(NCs) have attracted considerable attention due to their unique strong and broad orange-red emission band,presenting promising applications in the field of photoelectric devices.However,pristine Mn^(2+):CsPbCl_(3)NCs commonly suffer from low photoluminescence quantum yield(PL QY) and stability issues.Herein,we introduced europium ions(Eu^(3+))into Mn^(2+):CsPbCl_(3)NCs via the thermal injection synthesis method to obtain high performance Eu^(3+)and Mn^(2+)codoped CsPbCl_(3)(Eu^(3+)/Mn^(2+):CsPbCl_(3)) NCs.The maximum PL QY of the resulting Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs reaches up to 90.92%.It is found that the doping of Eu^(3+)ions significantly reduces the non-radiative recombination caused by high defect states,and improves the energy transfer efficiency from exciton to Mn^(2+),thereby boosting the PL performance.Moreover,doping Eu^(3+)ions notably improves the UV-light and water stability of Mn^(2+):CsPbCl_(3)NCs.We further demonstrate the application versatility of Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs in white light emitting diodes(WLEDs) and optical anticounterfeiting applications.This work provides a valuable perspective for the attainment of high performance Mn^(2+):CsPbCl_(3)NCs and lays a foundation for the codoping of other lanthanide ions to adjust the luminescence properties of Mn^(2+):CsPbCl_(3)NCs.展开更多
The growing demand for luminescent nanomaterials intended for various applications increases the necessity to develop and improve approaches to the creation of highly efficient nanosized phosphors.In current study,an ...The growing demand for luminescent nanomaterials intended for various applications increases the necessity to develop and improve approaches to the creation of highly efficient nanosized phosphors.In current study,an approach to enhancing the efficiency of red luminescence of monoclinic Y_(2)O_(3):Eu^(3+)with the particle size of~20 nm by creating the oxygen-enriched environment during the gas-phase synthesis was developed.To investigate the effect of oxygen amount during the synthesis on characteristics of the phosphor,a series of nano structured Y_(2)O_(3):Eu^(3+)with the addition of 0-40 vol%O_(2) to the main buffer gas Ar was synthesized by laser vaporization.It is shown that the amount of added O_(2) exerts virtually no effect on the phase composition and particle size,but significantly improves the luminescent characteristics of Y_(2)O_(3):Eu^(3+).Thus,the addition of 30 vol%O_(2) leads to virtually a 20-fold growth in the photoluminescence(PL)intensity caused by ^(5)D_(0)→^(7)F_(0-4) transitions in Eu^(3+)and an increase in the absolute PL quantum yield from 3%to 53%(λex=395 nm)compared to the sample synthesized without O_(2).The addition of oxygen also improves the emission color coordinates from(0.571,0.320)to(0.630,0.322)due to the removal of a considerable fraction of oxygen vacancies.The synthesized nanopowders are shown to be highly stable:upon storage under ambient conditions for two years.Quantum yield(QY)of the samples decreases by less than 2%.It is expected that the key features underlying the proposed approach will be useful for various methods used to synthesize oxide nanophosphors.展开更多
Organic small molecule fluorophores have been widely used in biology and biochemistry to study cellular structures and processes at high spatial and temporal resolution.Small-molecule dyes offer various benefits,such ...Organic small molecule fluorophores have been widely used in biology and biochemistry to study cellular structures and processes at high spatial and temporal resolution.Small-molecule dyes offer various benefits,such as high photostability,low molecular weight,and great biocompatibility.However,the poor brightness of most of conventional dyes in biological environments limits their use in high-quality superresolution fluorescence imaging.Chemists have conceived and developed many methods to enhance the brightness of fluorophores,including structural alterations that raise extinction coefficients and quantum yields.This review outlines current attempts and substantial advances achieved by chemists to improve the brightness of organic small-molecule fluorescent dyes,such as scaffold rigidification and twisted intramolecular charge transfer(TICT)inhibition.We think that this review will help researchers understand the chemical mechanisms involved in increasing the brightness of fluorophores for biological applications.展开更多
The exploitation of a highly selective and sensitive probe to detect both cancer marker and metal ion is of great importance.In this work,the "one stone two bird" agent of 1,10-phenanthroline(phen) is design...The exploitation of a highly selective and sensitive probe to detect both cancer marker and metal ion is of great importance.In this work,the "one stone two bird" agent of 1,10-phenanthroline(phen) is designed to disrupt the polymeric lanthanide MOFs(LnMOFs,[Ln(CHO_(2))_(3)]n,Ln=Tb,la;Eu,1 b,CHO_(2)=formic acid) {[Ln(CHO_(2))_(4)·(C_(2) H_(8) N)]n,Ln=Y,2 a;Gd,2 b;Dy,2 c,C_(2)H_(8) N=dimethylamine}) into a soluble mononuclear species [Ln(phen)_(2)(NO_(3))_(3),Ln=Tb,3 a;Eu,3 b] as well as to provide an antenna for efficient photons absorption,resulting in an ultra-high luminescence quantum yield(QY,90%) europium complex.The luminescence QY is among the highest record of monomeric(zero-dimensional) lanthanide complexes.Furthermore,mononuclear Tb3+complex(3 a) functions as a multiplex sensor towards both Fe^(2+)and cancer marker of 5-hydroxyindole-3-acetic acid(5-HIAA).Importantly,the limit of detection(LOD)for sensing 5-HIAA is an ultra-sensitive value of 1 × 10 s mol/L,which is even lower than that necessary for the early diagnosis of carcinoid tumors.More interestingly,sensing results in simulated urine reveals that 3 a has potential application for early diagnosis in the clinic.展开更多
Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentrati...Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x（TTA）3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x（TTA）3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x（TTA）3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x（TTA）3phens are of quasi-periodic variation with the change of the Gd3. dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x（TTA）3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3＋ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.展开更多
Compared with other transition metal Mxene derived quantum dots(MQD_(S)),Ta-based Mxene quantum dots have good functionality,but Ta-based Mxene quantum dots and their applications have not been studied so far.In this ...Compared with other transition metal Mxene derived quantum dots(MQD_(S)),Ta-based Mxene quantum dots have good functionality,but Ta-based Mxene quantum dots and their applications have not been studied so far.In this paper,we report for the first time the synthesis of high fluorescence quantum yield(QY) N-doped Ta_(4)C_(3) quantum dots(N-MQDs) using Ta_(4)C_(3) quantum dots in acid reflux damaged Ta_(4)C_(3) nanosheets as precursors and ethylenediamine as nitrogen source.The prepared N-MQDs have excellent blue photoluminescence(PL) properties,particle size is only 2.60 nm,QY is up to 23.4%,and good stability.In addition,it has been reported that N-MQDs can be used as fluorescent probe for detection of Fe;and remote force sensing analysis In liquid ion sensing,N-MQDS shows a unique selective quenching of Fe;with a detection limit as low as 2 μmol/L,and has great potential as a fast and super-sensitive fluorescent probe for the detection of heavy ion.More importantly,in solid mechanics sensing,the introduction of N-MQDs into self-healing hydrogels can be developed into a fluorescent hydrogel that can be used for accurate remote force measurement and applied in the field of mechanical sensing analysis.Therefore,Ta-based N-MQDs show excellent potential in the field of fluorescence sensing,which provides a door for multi-dimensional sensing of new materials in the future.展开更多
Long-emission carbon dots(CDs) is triggering immense enthusiasm on account of their intrinsic merits of high chemical stability and excellent optical properties.In this study,a facile and rapid approach was developed ...Long-emission carbon dots(CDs) is triggering immense enthusiasm on account of their intrinsic merits of high chemical stability and excellent optical properties.In this study,a facile and rapid approach was developed for the preparation of barium-doped carbon dots(Ba-CDs) with yellow fluo rescence emission and high quantum yields.Surface chemistry and the chemical architecture of the Ba-CDs was revealed under various spectroscopic methods.This work provides more insights into the effects of charge transfer caused by Ba heteroatoms,which is considered as the most challenging step in the investigation on luminescence mechanism.Remarkably,the prepared Ba-CDs were successfully applied as fluorescent probes in the detection of trace water in organic solvents(ethanol,isopropanol,acetone,tetrahydrofuran).Comparing with traditional fluorescent probes for water detection in organic solvents,Ba-CDs detection provides a more sensitive,much faster and more economical approach.展开更多
The luminescent properties of two Eu3＋ compounds based on quinoline-2-car- boxylic acid （Hqc）, [Na2Eu2（qc）6（CH3COO）2（H2O）4].2DMF （1） and [Eu2（qc）6（H2O）6].3H2O （2）, as well as their syntheses and struc...The luminescent properties of two Eu3＋ compounds based on quinoline-2-car- boxylic acid （Hqc）, [Na2Eu2（qc）6（CH3COO）2（H2O）4].2DMF （1） and [Eu2（qc）6（H2O）6].3H2O （2）, as well as their syntheses and structures are reported. Both compounds are formed by slow evaporation at room temperature and exhibit zero dimensional dinuclear structures. It is worth mentioning that a 4.5-fold enhancement in luminescent quantum yield is achieved by reducing the nonradiative deactivation, through which the quantum yield increases remarkably to 67.62% for 1 compared with 12.18% for 2.展开更多
Gdo.9xRxEUo.lOOH （R=Y, La） crystals were synthesized by a flux method using a mixture of NaOH and KOH as the flux. X-ray diffraction data were well refined using the Rietveld method assuming that the crystals had a ...Gdo.9xRxEUo.lOOH （R=Y, La） crystals were synthesized by a flux method using a mixture of NaOH and KOH as the flux. X-ray diffraction data were well refined using the Rietveld method assuming that the crystals had a monoclinic structre belonging to the P21/m space group. The unit cell volumes of the Gdo.9 xLaxEuo.OOH crystals increased with increasing x, whereas those of Gdo.9-xYxEUo.lOOH decreased with increasing x. The Commission Internationale de IEclairage （CIE） chromaticity coordinates of Gdo.9 xRxEUo.lOOH （R=Y, La） crystals were located in the red region and were nearly constant over the range ofx values considered. The fluorescence quantum yield Dr monotonically decreased with increasing x regardless of the ionic radii of the substitute ions. The fact that the Dr value of Lao.9EuoAOOH was greater than that of Gdo.gEUo.lOOH indicated that the observed decrease in the values of the Gdo.9-,LaxEuo.1OOH crystals up to x=0.3 could not be attributed to an increase in the distance between Eu3＋ ions or to a decrease in the Gd3＋ content. The decrease might be due to an increase of killer centers introduced by elemental substitutions with the larger ion.展开更多
The fluorescently labelled polymers including pyrene-labelled polystyrene(PyPS) and pyrene-labelled poly(methyl methacrylate)(PyPMMA) with narrow molecular weight distributions were synthesized by the atom transfer ra...The fluorescently labelled polymers including pyrene-labelled polystyrene(PyPS) and pyrene-labelled poly(methyl methacrylate)(PyPMMA) with narrow molecular weight distributions were synthesized by the atom transfer radical copolymerization(ATRCP) of styrene or methyl methacrylate with 1-pyrenemethyl methacrylate(PyMMA). The ultrathin PyPS and PyPMMA films with the thickness ranging from 30 nm to 400 nm supported on the quartz slides were prepared by spin-coating. The fluorescent quantum yield(QY) of the pyrene probe in the ultrathin polymer films was investigated by the photoluminescence spectrometer using an integrating sphere detector. The QY decreased with the reduction of film thickness in the sub-200 nm range.展开更多
Present solar cells are expensive making photovoitaic electricity only attractive whenever there is government incentive. This paper highlights the cost of photovoltaic classified according to first, second and third ...Present solar cells are expensive making photovoitaic electricity only attractive whenever there is government incentive. This paper highlights the cost of photovoltaic classified according to first, second and third generations. The first and second generations make up the current photovoltaic. The reasons for the efficiency limitation of the first and second generation photovoltaic are given. Nanoparticles such as quantum dots have confinement properties that can be exploited to improve solar cell efficiency and help reduce the cost. Quantum effect that support hot electron collection and multiple exciton generation through impact ionization are discussed. These form the basis of the future generation quantum dot solar cell.展开更多
Self-trapped excitons are prevalent in metal halide perovskites(MHPs)characterized by soft lattices and strong exciton-phonon coupling,emitting photons with broadband emission and large Stokes shifts,rendering them pa...Self-trapped excitons are prevalent in metal halide perovskites(MHPs)characterized by soft lattices and strong exciton-phonon coupling,emitting photons with broadband emission and large Stokes shifts,rendering them particularly well-suited for applications in light-emitting diodes.But their photoluminescence quantum yields(PLQY)are limited by both high exciton binding energy and halogen-vacancy-associated non-radiative recombination.Here,we show that PLQY could be enhanced by a factor of 5.6 from 16%to 89%through doping trace Ag into Cs_(2)NaBiCl_(6)double perovskites,superior to those of previous Cs_(2)NaBiCl_(6)-based emitters.Experimental and theoretical studies reveal that trace Ag-initiated covalent interactions could reduce the exciton binding energy by 0.12 eV due to local symmetry breaking,thus improving the photoexcitation process.Also,this covalent interaction could passivate Cl vacancy defects,suppressing non-radiative recombination.Therefore,Cs2NaBiCl6:0.7%Ag^(+)could accumulate active self-trapped excitons to obtain high PLQY.Assembly of near-infrared light-emitting diodes using Cs_(2)NaBiCl_(6):0.7%Ag^(+)illustrates their valuable applications in nondestructive spectral analysis and night vision illumination.This work shows an effective strategy of improving photoemission of MHPs with high PLQY for advanced optoelectronic applications.展开更多
基金Project supported by National Natural Science Foundation of China(21571162)the Guangdong Province Enterprise-University-Academy Collaborative Project(2012B091100474)
文摘A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^3+ samples showed broad excitation spectrum from 250 to 400 nm and presented characteristic emission transitions ^5D4→^7FJ(J=6, 5, 4, 3) of Tb^3+ under 313 nm excitation, which were located at about 488, 541, 584 and 620 nm. The emission intensities of Tb^3+ rose steadily in Sr3Gd2(Si3O9)2 host with the increase of Tb^3+ concentration even though Gd^3+ ions were completely replaced by Tb^3+ ions. The Ce^3+ ion as a sensitizer could efficiently improve the performance of Tb^3+ ion. First, with Ce^3+ co-doping, the excitation spectrum of Tb^3+ monitored at 541 nm showed a similar band that responds to the violet emission of Ce^3+ monitored at 416 nm. Second, the quantum yields of Sr3Gd2(Si3O9)2:Tb^3+ phosphors could be enhanced from 26.6% to 80.2% by co-doping Ce^3+. Finally, the co-doping of Ce^3+ was also effective to improve the thermal stability of Sr3Gd2(Si3O9)2:Tb^3+. As the temperature rose to 150 oC, the emission intensity of Tb^3+ remained at about 83.6% of that measured at room temperature, which was better than the commercial YAG:Ce phosphor in terms of their thermal quenching properties. These results indicated that the as-prepared Sr3Gd2(Si3O9)2:Tb^3+,Ce^3+ samples could be used as green emission phosphors for possible applications in near ultraviolet based WLEDs.
基金supported by the Program for New Century Excellent Talents in Fujian Province University。
文摘The major cytotoxic agent with most current photosensitizers used in photodynamic therapy(PDT)is widely believed to be singlet oxygen(^(1)O_(2)).Determination of the ^(1)O_(2) quantum yields for porphyrin-based photosensitizers,including hematoporphyrin derivative(HiPorfin),hematoporphyrin monomethyl ether(HMME)and photocarcinorin(PsD-007)in air-saturated dimethylformamide(DMF)solutions were performed by the direct measurement of their near-infrared luminescence.In addition,^(1)O_(2) quencher sodium azide was employed to confirm the ^(1)O_(2) generation from the investigated photosensitizers.The maximal ^(1)O_(2) luminescence occurs at about 1280 nm with full width at half maximum of 30 nm.The ^(1)O_(2) quantum yields were found to be 0.61±0.03,0.60±0.02 and 0.59±0.03 for HiPorfin,HMME and PsD-007,respectively.These results provide that these porphyrin-based photosensitizers produce ^(1)O_(2) under irradiation,which is of significance for the study of their photodynamic action in PDT.
文摘Theoretical dependence of the quantum yields on the size of Agnano-particle distribution from 0.8 nm to 37 nm embedded in BaOsemiconductor is discussed. The calculation results show that theincrease in Ag nano-particle diameter leads to the increase of thequantum yield threshold and the emergence of the rough Gaussian form,the results also shown that the greater increase in Ag nano-particlediameter causes the emergence of the exact Gaussian form and makesthe peaks rise up.
基金supported by Medical Science and Technology Research Project of Henan Province(Joint Construction Project)(No.LHGJ20200433)National Natural Science Foundation of China(No.52122308)。
文摘White light illumination is essential in daily life,however,the substantial amount of blue light it contains can damage human eyes.Therefore,it is important to block this high-energy blue light to protect visual health.In this study,yellow-emitting carbon dots(CDs)with a quantum yield exceeding 94%were synthesized using citric acid and urea.These CDs effectively absorb blue light.By incorporating them into polystyrene,multiple films termed CDs-based blue light blocking films(CBFs)were developed,each offering different levels of blue light absorption.These CBFs exhibited excellent transparency and efficient blue light filtering capabilities.This study highlights the potential of high quantum yield CDs,which specifically absorb blue light,as foundational materials for developing light-blocking solutions against highenergy short-wavelength light.
基金We appreciate the financial supports from the Board or Regent Supporting Fund(BORSF)Endowed Professorshipthe Lousiana State University Shreveport(LSUS)R&D Funds+1 种基金the Qingdao Municipal Science and Technology Commission(No.16-5-1-86-jch)the Scientific Research Foundation of Qingdao University of Science and Technology(QUST)(No.210/010022914).
文摘Carbon dots(CDs)with solvatochromic emission colors in different solvents have attracted much attention as a new class of luminescent nanomaterial owing to their facile synthesis and low production cost.In this work,we prepared two kinds of CDs with solvatochromic emissions:green emission CDs(G-CDs)and multicolor emission CDs(M-CDs).G-CDs synthesized from o-phenylenediamine exhibited weak photoluminescence emission(quantum yield 2.8%-6.1%)and 39 nm solvatochromic shifts(492-531 nm).In contrast,M-CDs prepared from o-phenylenediamine and 4-aminophenol showed 87 nm solvatochromic shift range(505-592 nm)and much higher photoluminescence quantum yield(18.4%-32.5%).The two CDs exhibited different emission,absorption,and photoluminescence lifetime.The origin of solvatochromic shifts and the formation mechanism of CDs were demonstrated by analyzing the structures and compositions of two CDs.High percentages of pyrrolic nitrogen and amino nitrogen make wider solvatochromic shifts and higher quantum yields.The results were well supported by density functional theory calculations.This effective strategy to expand solvatochromic shift range and improve quantum yields could open a new window to prepare satisfied solvatochromic carbon dots.
基金Project supported by the National Natural Science Foundation of China(U1904178.11704202.11504131,51374132)the Program for Science&Technology Innovation Talents in Universities of Henan Province(19HASTIT019).
文摘Considering the toxicity problem of lead-based perovskite quantum dots(PQDs),the lead-free Cs_(3)Bi_(2)Br_(g)PQDs has been recognized as one of the promising candidates.However,the low photoluminescence quantum yields(PLQYs)hinder its practical application in optoelectronic devices.Here,w e successfully prepared Sm^(3+)ions doped Cs_(3)Bi_(2)Br_(g)PQDs with effective white light-emission by modified ligandassisted recrystallization method.The realization of white light-emission is attributed to the broadband blue emission of excitons and the red emission(^(4)G_(5/2)-^(6)HJ(J=5/2,7/2,9/2))of Sm^(3+)ions for Sm^(3+)ions doped Cs_(3)Bi_(2)Br_(g)PQDs.More importantly,compared with the undoped Cs_(3)Bi_(2)Br_(g)PQDs,the PLQYs of Sm^(3+)ions doped Cs_(3)Bi_(2)Br_(g)PQDs are improved from 10.9%to 20.8%,and the anti-water stability is also obviously improved.Finally,the Sm^(3+)ions doped PQDs based white light-emitting diodes(LEDs)with luminous efficiency of 12.6 lm/W were explored,which indicates that there is a potential prospect of lead-free PQDs in white light lighting application.
基金supported by the Shandong Provincial Natural Science Foundation,China(No.ZR2020MA078)。
文摘Four benzocoumarin-based two-photon fluorescent probes(BH1-BH4)are proposed for ra-tiometric detection of hypochlorous acid(HClO)and their two-photon sensing perfor-mance are evaluated by means of time-dependent density func-tional theory and quadratic re-sponse theory.The effects of benzene-fused position on Stokes shift,fluorescence quantum yield and two-photon absorption are discussed comprehensively.The results show that fusing a benzene ring in coumarin can enhance Stokes shift efficiently.The benzene-fused position has important effects on these photophysical properties.The benzo[g]coumarins(BH1)and benzo[f]coumarins(BH2)derivatives have larger Stokes shifts in comparison with benzo[h]coumarins(BH3)and dihydrophenazine(BH4)derivatives.The two-photon absorp-tion of benzo[f]coumarins(BH2)derivative is much smaller than those of other benzo-coumarins derivatives.The large Stokes shift and increased two-photon action cross section can be achieved simultaneously in the dihydrophenazine(BH4)derivative.Therefore,the de-signed BH4 is expected to have superior performance for the ratiometric detection of HClO.To explore the reasons behind these effects,the intramolecular charge transfer degrees are il-lustrated quantitatively by plotting the hole-electron isosurface map,and the relation be-tween charge transfer and Stokes shift is revealed.A two-state model analysis is employed to understand two-photon absorption ability.Moreover,the fluorescence near-quenching mecha-nism of the product molecules B1 and B3 is explained by analyzing reorganization energy and Huang-Rhys factor,as well as related normal mode.Our research could contribute to the effi-cient design of ratiometric two-photon fluorescent probes with large Stokes shift and signifi-cant two-photon action cross section.
基金supported by the Natural Science Foundation of the Science and Technology Department of Jilin Province(No.20220101086JC)。
文摘In this study,a simple and effective ratiometric fluorescence method has been developed for carbaryl detection,utilizing red emissive carbon dots(R-CDs).The underlying principle of this proposed strategy relies on the rapid hydrolysis of carbaryl under an alkaline condition and production of 1-naphthol with blue-emission at 462 nm.Furthermore,the as-synthesized R-CDs(Em.677 nm),serve as a reference,enhancing the visual tracking of carbaryl through the transformation of fluorescent color from red to blue.The concentration of carbaryl exhibits a commendable linear correlation with the ratio of fluorescence intensity,ranging from 0 to 20μg/m L(R^(2)=0.9989)with a low detection limit of 0.52 ng/m L.Additionally,the described methodology can be used for the enzyme-free visual assay of carbaryl,even in the presence of other carbamate pesticides and metal ions,in tap water and lake water samples with excellent accuracy(spiked recoveries,94%-106.1%),high precision(relative standard deviation(RSD)≤2.42),and remarkable selectivity.This fast and highly sensitive naked-eye ratiometric sensor holds immense promise for carbaryl detection in intricate environments and food safety fields.
基金Project supported by the National Natural Science Foundation of China (12174075)the Scientific and Technological Bases and Talents of Guangxi (Guike AD21220016)+1 种基金Guangxi Science and Technology Major Project(AA23073018)the special fund for Guangxi Bagui Scholars。
文摘Mn^(2+)-doped CsPbCl_(3)(Mn^(2+):CsPbCl_(3)) nanocrystals(NCs) have attracted considerable attention due to their unique strong and broad orange-red emission band,presenting promising applications in the field of photoelectric devices.However,pristine Mn^(2+):CsPbCl_(3)NCs commonly suffer from low photoluminescence quantum yield(PL QY) and stability issues.Herein,we introduced europium ions(Eu^(3+))into Mn^(2+):CsPbCl_(3)NCs via the thermal injection synthesis method to obtain high performance Eu^(3+)and Mn^(2+)codoped CsPbCl_(3)(Eu^(3+)/Mn^(2+):CsPbCl_(3)) NCs.The maximum PL QY of the resulting Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs reaches up to 90.92%.It is found that the doping of Eu^(3+)ions significantly reduces the non-radiative recombination caused by high defect states,and improves the energy transfer efficiency from exciton to Mn^(2+),thereby boosting the PL performance.Moreover,doping Eu^(3+)ions notably improves the UV-light and water stability of Mn^(2+):CsPbCl_(3)NCs.We further demonstrate the application versatility of Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs in white light emitting diodes(WLEDs) and optical anticounterfeiting applications.This work provides a valuable perspective for the attainment of high performance Mn^(2+):CsPbCl_(3)NCs and lays a foundation for the codoping of other lanthanide ions to adjust the luminescence properties of Mn^(2+):CsPbCl_(3)NCs.
基金Project supported by Russian Science Foundation(22-73-00106)partly by NIIC project(121031700313-8,M.Rakhmanova,PL kinetics study)。
文摘The growing demand for luminescent nanomaterials intended for various applications increases the necessity to develop and improve approaches to the creation of highly efficient nanosized phosphors.In current study,an approach to enhancing the efficiency of red luminescence of monoclinic Y_(2)O_(3):Eu^(3+)with the particle size of~20 nm by creating the oxygen-enriched environment during the gas-phase synthesis was developed.To investigate the effect of oxygen amount during the synthesis on characteristics of the phosphor,a series of nano structured Y_(2)O_(3):Eu^(3+)with the addition of 0-40 vol%O_(2) to the main buffer gas Ar was synthesized by laser vaporization.It is shown that the amount of added O_(2) exerts virtually no effect on the phase composition and particle size,but significantly improves the luminescent characteristics of Y_(2)O_(3):Eu^(3+).Thus,the addition of 30 vol%O_(2) leads to virtually a 20-fold growth in the photoluminescence(PL)intensity caused by ^(5)D_(0)→^(7)F_(0-4) transitions in Eu^(3+)and an increase in the absolute PL quantum yield from 3%to 53%(λex=395 nm)compared to the sample synthesized without O_(2).The addition of oxygen also improves the emission color coordinates from(0.571,0.320)to(0.630,0.322)due to the removal of a considerable fraction of oxygen vacancies.The synthesized nanopowders are shown to be highly stable:upon storage under ambient conditions for two years.Quantum yield(QY)of the samples decreases by less than 2%.It is expected that the key features underlying the proposed approach will be useful for various methods used to synthesize oxide nanophosphors.
基金supported by the National Science Foundation for Distinguished Young Scholars(No.22325401)the National Natural Science Foundation of China(No.22404049)the China Postdoctoral Science Foundation(No.2024M750866)。
文摘Organic small molecule fluorophores have been widely used in biology and biochemistry to study cellular structures and processes at high spatial and temporal resolution.Small-molecule dyes offer various benefits,such as high photostability,low molecular weight,and great biocompatibility.However,the poor brightness of most of conventional dyes in biological environments limits their use in high-quality superresolution fluorescence imaging.Chemists have conceived and developed many methods to enhance the brightness of fluorophores,including structural alterations that raise extinction coefficients and quantum yields.This review outlines current attempts and substantial advances achieved by chemists to improve the brightness of organic small-molecule fluorescent dyes,such as scaffold rigidification and twisted intramolecular charge transfer(TICT)inhibition.We think that this review will help researchers understand the chemical mechanisms involved in increasing the brightness of fluorophores for biological applications.
基金supported by the National Natural Science Foundation of China (51962008)。
文摘The exploitation of a highly selective and sensitive probe to detect both cancer marker and metal ion is of great importance.In this work,the "one stone two bird" agent of 1,10-phenanthroline(phen) is designed to disrupt the polymeric lanthanide MOFs(LnMOFs,[Ln(CHO_(2))_(3)]n,Ln=Tb,la;Eu,1 b,CHO_(2)=formic acid) {[Ln(CHO_(2))_(4)·(C_(2) H_(8) N)]n,Ln=Y,2 a;Gd,2 b;Dy,2 c,C_(2)H_(8) N=dimethylamine}) into a soluble mononuclear species [Ln(phen)_(2)(NO_(3))_(3),Ln=Tb,3 a;Eu,3 b] as well as to provide an antenna for efficient photons absorption,resulting in an ultra-high luminescence quantum yield(QY,90%) europium complex.The luminescence QY is among the highest record of monomeric(zero-dimensional) lanthanide complexes.Furthermore,mononuclear Tb3+complex(3 a) functions as a multiplex sensor towards both Fe^(2+)and cancer marker of 5-hydroxyindole-3-acetic acid(5-HIAA).Importantly,the limit of detection(LOD)for sensing 5-HIAA is an ultra-sensitive value of 1 × 10 s mol/L,which is even lower than that necessary for the early diagnosis of carcinoid tumors.More interestingly,sensing results in simulated urine reveals that 3 a has potential application for early diagnosis in the clinic.
基金supported by the National Natural Science Foundation of China(No.50973003)Anhui Science and TechnologyProgram(Nos.KJ2012B135,KJ2012A217,KJ2012B136,KJ2011A210, 1301042112)+1 种基金Natural Science Foundation of Fuyang Normal College (Nos.2011HJJC02ZD,2011HJJC01ZD,2011HJJC04YB,2010FSKJ01ZD, 2013FSKJ03ZD)Incubator Fund of Scientific and Technological achievements of Fuyang Normal College(Nos.2013KJFH03, 2013KJFH01)
文摘Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x（TTA）3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x（TTA）3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x（TTA）3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x（TTA）3phens are of quasi-periodic variation with the change of the Gd3. dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x（TTA）3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3＋ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.
基金supported by the National Natural Science Foundation of China (No. 81972901)the Key R&D Plan of Chenzhou (No. ZDYF202008)+1 种基金the Discipline Leader Startup Fund of Huazhong University of Science and Technology Union Shenzhen Hospital (No. YN2021002)Science Foundation of China University of Petroleum,Beijing (Nos. 2462019QNXZ02, 2462019BJRC007)。
文摘Compared with other transition metal Mxene derived quantum dots(MQD_(S)),Ta-based Mxene quantum dots have good functionality,but Ta-based Mxene quantum dots and their applications have not been studied so far.In this paper,we report for the first time the synthesis of high fluorescence quantum yield(QY) N-doped Ta_(4)C_(3) quantum dots(N-MQDs) using Ta_(4)C_(3) quantum dots in acid reflux damaged Ta_(4)C_(3) nanosheets as precursors and ethylenediamine as nitrogen source.The prepared N-MQDs have excellent blue photoluminescence(PL) properties,particle size is only 2.60 nm,QY is up to 23.4%,and good stability.In addition,it has been reported that N-MQDs can be used as fluorescent probe for detection of Fe;and remote force sensing analysis In liquid ion sensing,N-MQDS shows a unique selective quenching of Fe;with a detection limit as low as 2 μmol/L,and has great potential as a fast and super-sensitive fluorescent probe for the detection of heavy ion.More importantly,in solid mechanics sensing,the introduction of N-MQDs into self-healing hydrogels can be developed into a fluorescent hydrogel that can be used for accurate remote force measurement and applied in the field of mechanical sensing analysis.Therefore,Ta-based N-MQDs show excellent potential in the field of fluorescence sensing,which provides a door for multi-dimensional sensing of new materials in the future.
基金financially supported by the National Natural Science Foundation of China (NSFC,No.21805024)Science Foundation of China University of Petroleum (Nos. 2462019QNXZ02,2462018BJC004)+1 种基金the Scientifc and Technological Research Program of Chongqing Municipal Education Commission (No.KJ QN202001335)the Research Program ofYongchuan Science and Technology Commission (Ycstc,No.2018nb1402)。
文摘Long-emission carbon dots(CDs) is triggering immense enthusiasm on account of their intrinsic merits of high chemical stability and excellent optical properties.In this study,a facile and rapid approach was developed for the preparation of barium-doped carbon dots(Ba-CDs) with yellow fluo rescence emission and high quantum yields.Surface chemistry and the chemical architecture of the Ba-CDs was revealed under various spectroscopic methods.This work provides more insights into the effects of charge transfer caused by Ba heteroatoms,which is considered as the most challenging step in the investigation on luminescence mechanism.Remarkably,the prepared Ba-CDs were successfully applied as fluorescent probes in the detection of trace water in organic solvents(ethanol,isopropanol,acetone,tetrahydrofuran).Comparing with traditional fluorescent probes for water detection in organic solvents,Ba-CDs detection provides a more sensitive,much faster and more economical approach.
基金Supported by the National Natural Science Foundation of China(No.21501075 and 21501076)the Natural Science Foundation of Jiangsu Province(No.BK20150226)+1 种基金Open Foundation of State Key Laboratory of Structure Chemistry(20170022)Undergraduate Students Project of Jiangsu
文摘The luminescent properties of two Eu3＋ compounds based on quinoline-2-car- boxylic acid （Hqc）, [Na2Eu2（qc）6（CH3COO）2（H2O）4].2DMF （1） and [Eu2（qc）6（H2O）6].3H2O （2）, as well as their syntheses and structures are reported. Both compounds are formed by slow evaporation at room temperature and exhibit zero dimensional dinuclear structures. It is worth mentioning that a 4.5-fold enhancement in luminescent quantum yield is achieved by reducing the nonradiative deactivation, through which the quantum yield increases remarkably to 67.62% for 1 compared with 12.18% for 2.
基金supported by Japan Society for the Promotion of Science(JSPS)KAKENHI Grants(2156069624560827)
文摘Gdo.9xRxEUo.lOOH （R=Y, La） crystals were synthesized by a flux method using a mixture of NaOH and KOH as the flux. X-ray diffraction data were well refined using the Rietveld method assuming that the crystals had a monoclinic structre belonging to the P21/m space group. The unit cell volumes of the Gdo.9 xLaxEuo.OOH crystals increased with increasing x, whereas those of Gdo.9-xYxEUo.lOOH decreased with increasing x. The Commission Internationale de IEclairage （CIE） chromaticity coordinates of Gdo.9 xRxEUo.lOOH （R=Y, La） crystals were located in the red region and were nearly constant over the range ofx values considered. The fluorescence quantum yield Dr monotonically decreased with increasing x regardless of the ionic radii of the substitute ions. The fact that the Dr value of Lao.9EuoAOOH was greater than that of Gdo.gEUo.lOOH indicated that the observed decrease in the values of the Gdo.9-,LaxEuo.1OOH crystals up to x=0.3 could not be attributed to an increase in the distance between Eu3＋ ions or to a decrease in the Gd3＋ content. The decrease might be due to an increase of killer centers introduced by elemental substitutions with the larger ion.
基金financially supported by the National Natural Science Foundation of China(Nos.21174167 and 51573212)the Natural Science Foundation of Guangdong Province(Nos.S2013030013474 and 2014A030313178)
文摘The fluorescently labelled polymers including pyrene-labelled polystyrene(PyPS) and pyrene-labelled poly(methyl methacrylate)(PyPMMA) with narrow molecular weight distributions were synthesized by the atom transfer radical copolymerization(ATRCP) of styrene or methyl methacrylate with 1-pyrenemethyl methacrylate(PyMMA). The ultrathin PyPS and PyPMMA films with the thickness ranging from 30 nm to 400 nm supported on the quartz slides were prepared by spin-coating. The fluorescent quantum yield(QY) of the pyrene probe in the ultrathin polymer films was investigated by the photoluminescence spectrometer using an integrating sphere detector. The QY decreased with the reduction of film thickness in the sub-200 nm range.
文摘Present solar cells are expensive making photovoitaic electricity only attractive whenever there is government incentive. This paper highlights the cost of photovoltaic classified according to first, second and third generations. The first and second generations make up the current photovoltaic. The reasons for the efficiency limitation of the first and second generation photovoltaic are given. Nanoparticles such as quantum dots have confinement properties that can be exploited to improve solar cell efficiency and help reduce the cost. Quantum effect that support hot electron collection and multiple exciton generation through impact ionization are discussed. These form the basis of the future generation quantum dot solar cell.
基金the National Natural Science Foundation of China(92163117,52072389)the Central Guidance on Science and Technology Development Fund of Zhejiang Province(2024ZY01011)for financial support。
文摘Self-trapped excitons are prevalent in metal halide perovskites(MHPs)characterized by soft lattices and strong exciton-phonon coupling,emitting photons with broadband emission and large Stokes shifts,rendering them particularly well-suited for applications in light-emitting diodes.But their photoluminescence quantum yields(PLQY)are limited by both high exciton binding energy and halogen-vacancy-associated non-radiative recombination.Here,we show that PLQY could be enhanced by a factor of 5.6 from 16%to 89%through doping trace Ag into Cs_(2)NaBiCl_(6)double perovskites,superior to those of previous Cs_(2)NaBiCl_(6)-based emitters.Experimental and theoretical studies reveal that trace Ag-initiated covalent interactions could reduce the exciton binding energy by 0.12 eV due to local symmetry breaking,thus improving the photoexcitation process.Also,this covalent interaction could passivate Cl vacancy defects,suppressing non-radiative recombination.Therefore,Cs2NaBiCl6:0.7%Ag^(+)could accumulate active self-trapped excitons to obtain high PLQY.Assembly of near-infrared light-emitting diodes using Cs_(2)NaBiCl_(6):0.7%Ag^(+)illustrates their valuable applications in nondestructive spectral analysis and night vision illumination.This work shows an effective strategy of improving photoemission of MHPs with high PLQY for advanced optoelectronic applications.
