In recent years,cellulose-based fluorescent polymers have received considerable attention.However,conventional modification methods face challenges such as insolubility in most solvents,fluorescence instability,and en...In recent years,cellulose-based fluorescent polymers have received considerable attention.However,conventional modification methods face challenges such as insolubility in most solvents,fluorescence instability,and environmental risks.In this study,a novel biosynthesis strategy was developed to fabricate fluorescent cellulose by adding fluorescent glucose derivatives to a bacterial fermentation broth.The metabolic activity of bacteria is utilized to achieve in situ polymerization of glucose and its derivatives during the synthesis of bacterial cellulose.Owing to the structural similarity between triphenylamine-modified glucose(TPA-Glc N)and glucose monomers,the TPA-Glc N were efficiently assimilated by the bacterial cells and incorporated into the cellulose matrix,resulting in a uniform distribution of fluorescence.The fluorescence color and intensity of the obtained cellulose could be adjusted by varying the amount of the fluorescent glucose derivatives.Compared to the fluorescent cellulose synthesized through physical dyeing,the fluorescence of the products obtained by in situ polymerization showed higher intensity and stability.Furthermore,fluorescent bacterial cellulose can be hydrolyzed into nanocellulose-based ink,which demonstrates exceptional anti-counterfeiting capabilities under UV light.This biosynthesis method not only overcomes the limitations of traditional modification techniques but also highlights the potential of microbial systems as platforms for synthesizing functional polymers.展开更多
Color-tunable phosphors Sr0.94MoO4：xEu^3＋, （0.06 - x）Tb^3＋ were synthesized rapidly by microwave ra- diation method with active carbon particle as microwave absorbent. The synthesized phosphors were investigated ...Color-tunable phosphors Sr0.94MoO4：xEu^3＋, （0.06 - x）Tb^3＋ were synthesized rapidly by microwave ra- diation method with active carbon particle as microwave absorbent. The synthesized phosphors were investigated by X-ray powder diffraction （XRD） and fluorescence spec- trophotometer. The effects of the ratio of Eu^3＋ and Tb^3＋ on the phase structure and luminescent properties of the phos- phors were discussed. The results show that Eu^3＋,Tb^3＋-doped samples can be well indexed to the pure tetragonal scheelite- type SrMoO4, indicating that Eu^3＋ and Tb^3＋ are effectively doped into the SrMoO4 host lattices. The as-synthesized Sro.94MoO4：xEu^3＋,（0.06 - x）Tb^3＋ phosphors have two luminescent centers （Eu^3＋ and Tb^3＋）, which can show red and green emissions under ultraviolet light excitation, respec- tively. Doping concentration of Eu^3＋ and Tb^3＋ has great effect on the intensity of emission peaks and the chromaticity of the samples, and the full color between green and red light can be achieved by adjusting the relative concentration of Eu^3＋ and Tb^3＋.展开更多
A self-luminescence KYb3 F10 material was obtained via a mild hydrothermal method.Its structure,morphology and the corresponding luminescence properties were studied.There is a self-luminesce nce based on the effectiv...A self-luminescence KYb3 F10 material was obtained via a mild hydrothermal method.Its structure,morphology and the corresponding luminescence properties were studied.There is a self-luminesce nce based on the effective recombination of electron and hole on surface defects or electronic centers in KYb3 F10.The pH values have significant impact on crystallinity and self-luminescent intensity of target products.With the introduction of Tb3+and Eu3+into KYb3 F10 matrix,a series of color-tunable emission can be achieved.Simultaneously,Tb3+and Eu3+can also affect the self-luminescent intensity of host slightly.Although there is no obvious energy transfer between host and activators,Tb3+has a distinct sensitive effect on Eu3+ascribed to the energy transfer between Tb3+and Eu3+.In addition,the thermal stability was carefully investigated,which demonstrate the materials can be as a candidate in fluorescent lamps and displays.展开更多
A series of color-tunable KLaSiO4：Ce3＋,Mn2＋phosphors were successfully prepared and the luminescent properties were investigated. Upon excitation at 290 nm, the emission spectra of KLaSiO4：Ce3＋,Mn2＋phosphors inc...A series of color-tunable KLaSiO4：Ce3＋,Mn2＋phosphors were successfully prepared and the luminescent properties were investigated. Upon excitation at 290 nm, the emission spectra of KLaSiO4：Ce3＋,Mn2＋phosphors included a blue emission band and a red emission band. Increasing the doping concentration of Mn2＋ions, the red emission was strengthened considerably, and the blue emission of Ce3＋ was reduced, owing to the efficient energy transfer. The composition optimized KLa0.96SiO4：0.02Ce3＋,0.02Mn2＋sample exhibited the white light emission brightly with the chromaticity coordinates of （0.331, 0.337）. Therefore, KLaSiO4：Ce3＋, Mn2＋could be used as a white phosphor candidate for white light-emitting diodes devices.展开更多
An efficient color-tunable hybrid white organic light-emitting diode is demonstrated with double interlayers of 2,7-bis(carbazol-9-yl)-9,9-ditoylfluo- rene/2-(diphenylphosphoryl) spiroflu-orene (DMFL-CBP/SPPO1) insert...An efficient color-tunable hybrid white organic light-emitting diode is demonstrated with double interlayers of 2,7-bis(carbazol-9-yl)-9,9-ditoylfluo- rene/2-(diphenylphosphoryl) spiroflu-orene (DMFL-CBP/SPPO1) inserted between blue fluorescent and yellow phosphorescent-emitting layers, and exhibits Commission Internationale de l’Eclairage (CIE1931) ranging from warm white (0.4368, 0.4497) to cool white (0.2781, 0.2896) with driving current density from 0.2 to 40 mA/cm2. The recombination of singlet and the triplet excitons in blue fluores-cent-emitting layer and yellow phosphorescent-emitting layer, respectively, can be modulated by both the thickness of these double interlayers and the applied current densities.展开更多
Using a color-tunable organic light-emitting diode (CT-OLED) can accord with the circadian cycle of humans and realize healthy lighting. The variation range of the correlated color temperature (CCT) is an important pa...Using a color-tunable organic light-emitting diode (CT-OLED) can accord with the circadian cycle of humans and realize healthy lighting. The variation range of the correlated color temperature (CCT) is an important parameter to measure the performance of CT-OLEDs. In this paper, the effect of changing the utilization of phosphorescent materials and the position of the recombination zone (RZ) in the device are investigated by changing the thickness of the emissive layer (EML) and the doping ratio of the host and vip materials. The results show that reducing the red phosphorescent material and improving the blue phosphorescent material can affect the change direction of CCT, but it is not enough to expand the span of CCT (ΔCCT). It is more conducive to improving ΔCCT by more reasonable regulation of the position of the main RZ in EML and the energy transfer from the blue sub-EML to the red sub-EML. Device D obtains the best electro-optic and spectral characteristics, in which the maximum ΔCCT is 5746 K (2661 - 8407 K) as the voltage changes from 3.75 V to 9.75 V, the maximum current efficiency and luminance reach 18.34 cd·A<sup>-1</sup> and 12,100 cd·m<sup>-2</sup>, respectively.展开更多
The color-tunable white organic light-emitting diode (CT-WOLED) with wide correlation color temperature (CCT) has many advantages in optimizing the artificial light source to adapt to the human physiological cycle. Th...The color-tunable white organic light-emitting diode (CT-WOLED) with wide correlation color temperature (CCT) has many advantages in optimizing the artificial light source to adapt to the human physiological cycle. The research on the change trend of CCT and the law of extending the change range of CCT will help to further improve the performance of this kind of device. The present work fabricated a series of CT-WOLED devices with a simple structure, which are all composed of two ultra-thin phosphor layers (PO-01 and Flrpic) and a spacer interlayer. The yellow interface exciplex (TCTA/PO-T2T) formed between the spacer layer (PO-T2T) and transmission material (TCTA) in EML will decrease the CCT value at low voltage. The relationship between the energy transfer in EML and CCT change trend is investigated by adjusting the interface exciplexes and the thickness of the interlayer or the phosphor layer in devices A, B and C, respectively. The results demonstrate that a simple OLED device with an interlayer inserted between two ultra-thin phosphor layers can achieve a wider CCT span from 3359 K to 6451 K at voltage increases from 2.75 V to 8.25 V. .展开更多
Four kinds of bis(N-alkylsalicylaldiminato) zinc(II) complexes were synthesized, and their molecular structures were determined by FT-IR and elemental analysis. Their photoluminescence properties were determined, whic...Four kinds of bis(N-alkylsalicylaldiminato) zinc(II) complexes were synthesized, and their molecular structures were determined by FT-IR and elemental analysis. Their photoluminescence properties were determined, which indicated that they could emit strong fluorescence varying from blue to yellow to reddish orange depending on their different molecular structures. They had good thermostability, solubility and film forming capability, and can be used as organic lectroluminescent materials. These new complexes may afford the feasibility to realize full-color display with materials based on similar molecular structures.展开更多
Achieving color-tunable room-temperature phosphorescence(RTP),especially including blue RTP from a single-component polymer still faces a formidable challenge.Herein,we wisely choose conformation-dependent phenothiazi...Achieving color-tunable room-temperature phosphorescence(RTP),especially including blue RTP from a single-component polymer still faces a formidable challenge.Herein,we wisely choose conformation-dependent phenothiazine with trifluoromethyl substituent as the side group of the phosphor monomer(Cz PT)and then copolymerize it with N-isopropylacrylamide(NIPAM)through photopolymerization to obtain polymers PPCz PTs.Time-dependent color-tunable phosphorescence from unusual quasi-equatorial(eq)to quasi-axial(ax)conformers are obtained,and the RTP color changes from orange(550 nm)to blue(470 nm)with phosphorescence lifetime up to 0.96 s.The theoretical calculations confirm that the quasi-axial conformer is the preferred structure that facilitates the formation of intramolecular hydrogen bonds on the trifluoromethyl group.The EPR spectra illustrate that the persistent UV irradiation generates radical cations to induce the conformational transitions first,followed by photopolymerization immobilizing the ax conformation in PPCz PTs.Applications of data encryption and anti-counterfeiting are fabricated to show prompt and delayed multicolor information.This work affords a simple and feasible avenue for two-dimensional color tunable room temperature phosphorescence from a single-component polymer.展开更多
Chiral B,N-doped polycyclic aromatic hydrocarbons with circularly polarized luminescence(CPL) and small full-width at halfmaxima(FWHM) are promising multiple resonance(MR) emitters for CP organic light-emitting diodes...Chiral B,N-doped polycyclic aromatic hydrocarbons with circularly polarized luminescence(CPL) and small full-width at halfmaxima(FWHM) are promising multiple resonance(MR) emitters for CP organic light-emitting diodes(CP-OLEDs).This work presents a pair of chiral MR enantiomers,P/M-o[B-N]_(2)N_(2),featuring B–N bonds incorporated within a[7]-helicene skeleton.These enantiomers exhibit narrow 0-0 and 0-1 electronic transition bands,whose relative intensity can be fine-tuned by increasing doping concentrations,resulting in redshifts of the emission peak from 542 to 592 nm.The enantiomers show mirrorsymmetric CPL spectra with an asymmetry factor(|g_(PL)|) of 1.0×10^(-3).The hyperfluorescent CP-OLEDs with double-sensitized emitting layers display a FWHM of 33 nm,an external quantum efficiency of 25.1%,and a|g_(EL)|factor of 7.7×10^(-4).Notably,the CP-OLEDs realize color-tunable CP electroluminescence peak from 553 to 613 nm by regulating the vibrational coupling.This work provides a novel concept for the design of helical CP-MR materials and CP-OLEDs,highlighting their potential for future applications in advanced optoelectronic devices.展开更多
In this work, novel phosphors Na5Gd(WO4)4: Tb^3+/Yb^3+ and Na5Gd(WO4)4: Tb^3+/Er^3+/Yb^3+ phosphors were synthesized by the solid state reaction method. The photoluminescence properties were investigated. The introduc...In this work, novel phosphors Na5Gd(WO4)4: Tb^3+/Yb^3+ and Na5Gd(WO4)4: Tb^3+/Er^3+/Yb^3+ phosphors were synthesized by the solid state reaction method. The photoluminescence properties were investigated. The introduction of Er^3+ to NGW: Tb^3+/Yb^3+ was used to modify the chromaticity coordinates, then providing a good color tunable property. The change in the chromaticity coordinates induces the shift of emission color from yellow-green to blue-green for NGW: Tb^3+/Er^3+/Yb^3+ as the temperature increases. All the results indicate that the NGW: Er^3+/Tb^3+/Yb^3+ phosphors may be used as optical temperature sensing materials.展开更多
A tunable luminescence from red to blue in Eu-doped mesoporous AIPO4 glass is achieved by adjusting the annealing temperature. With increasing annealing temperature, the increased Eu^3＋ ions reduction changes the lum...A tunable luminescence from red to blue in Eu-doped mesoporous AIPO4 glass is achieved by adjusting the annealing temperature. With increasing annealing temperature, the increased Eu^3＋ ions reduction changes the luminescence of the obtained glass. The abnormal reduction of Eu^3＋ to Eu^2＋ occurs in A1PO4 mesoporous glass at relative low annealed temperatures from 600 to 800 ~C in air. The presence of Eu^2＋ ions, which are reduced from Eu^3＋ by hole-electron pairs, is revealed by XPS spectra. Our results indicate the mesoporous AlPO4 glass is a suitable matrix to incorporate Eu ions as the tunable luminescent light sources or LEDs.展开更多
Nonconjugated polymer dots(PDs)without largely conjugated structures entitle their advantages such as environment friendliness,nontoxicity,and intrinsic fluorescence.However,color-tunable PDs remain a challenge.Herein...Nonconjugated polymer dots(PDs)without largely conjugated structures entitle their advantages such as environment friendliness,nontoxicity,and intrinsic fluorescence.However,color-tunable PDs remain a challenge.Herein,polyvinyl pyrrolidone(PVP)and ascorbic acid(AA)are used to synthesize nonconjugated PDs,namely,PA PDs with intensive blue emission.The introduction of a third component,m-phenylenediamine(MPD),redshifted the emission to green.The asprepared color-tunable blue to green emissive PDs exhibit excellent properties,whether in solution or in solid state,originated from the mechanism of clusteringtriggered emission(CTE)induced by the overlap of electron-rich atoms,the strong inter/intrachain interaction.The quantum yields of blue and green PDs reached up to 15.07%and 28.22%,respectively.Furthermore,PA PDs were successfully applied to the highly efficient photocatalytic degradation for dyes:methylene blue(MB)and methyl orange(MO)were degraded by 89.9%and 93.8%within 20 min under visible light,respectively.展开更多
Ionically bonded organic metal halide perovskite-like luminescent materials,which incorporate organic cations and metal halides,have emerged as a versatile multicomponent material system.However,these materials still ...Ionically bonded organic metal halide perovskite-like luminescent materials,which incorporate organic cations and metal halides,have emerged as a versatile multicomponent material system.However,these materials still face challenges in terms of low phosphorescence quantum yields and limited long persistent luminescence(LPL)colors.Herein,we present the design and synthesis of an intraligand chargetransfer organic-based metal halide perovskite-like material,in which organic cations form a compact supramolecular hydrogen-bonded organic framework(HOF)structure,exhibiting crystallization-induced phosphorescence emission of ligand,while metal halides form a unique two-dimensional(2D)structure that displays intrinsic self-trapped excitons(STE)emission under the radiation of UV light.Notably,the metal halide hybrid is found to exhibit enhanced phosphorescent photoluminescence efficiency of up to 81.05%and tunable LPL from cyan to orange compared to the pristine organic phosphor,due to the structural distortion and scaffolding effects of 2D metal halides as well as a well-packed HOF structure.Optical characterizations and theoretical calculations reveal that charge transfer from organic cations and halogen to ligand as well as STE from inorganic layers are responsible for the tunable LPL.Meanwhile,the high-efficiency phosphorescent quantum yield is attributed to stronger hydrogen bond stacking as well as structural distortion of metal halogen bands.Thus,the obtained LPL provides potentials in anti-counterfeiting,security systems,and so on.展开更多
Investigation on the bright and stable upconversion(UC)phosphors with multicolor emissions is fundamental and significant for the frontier applications of display and tempe rature probe.He re,dive rse emitting colors ...Investigation on the bright and stable upconversion(UC)phosphors with multicolor emissions is fundamental and significant for the frontier applications of display and tempe rature probe.He re,dive rse emitting colors with blue,cyan and yellowish green,which are caused by the energy transfer and crossrelaxation processes,are obtained by altering Er^3+,Tm^3+and Yb^3+concentrations in Er3+singly,Er^3+-Tm^3+-Yb^3+co-and tri-doped double perovskite La2ZnTiO6(LZT)phosphors synthesized by a simple solid-state reaction.In addition,excellent infrared emission at 801 nm located at"first biological windo w"is collected in Tm^3+-Yb^3+co-doped phosphors.Meanwhile,the temperature sensing properties based on the thermally coupled levels((^2H11/2)/(^4S3/2))of Er3+ions were analyzed from 298 to 573 K of LZT:0.15 Er^3+/0.10 Yb^3+phosphor,demonstrating that the maximal sensitivity value is about56×10^-4 K^-1 at 448 K.All these results imply that this kind of UC material has potential applications in display,bioimaging and optical device.展开更多
A series of single phase,warm white light emitting phosphors,Gd(P_(x)V_(1−x))O_(4):y at%Sm^(3+),with 1 at%Bi^(3+) doping concentration were synthesized by high temperature solid state method in this work.The experimen...A series of single phase,warm white light emitting phosphors,Gd(P_(x)V_(1−x))O_(4):y at%Sm^(3+),with 1 at%Bi^(3+) doping concentration were synthesized by high temperature solid state method in this work.The experimental results indicate broadband cyan emission of Bi^(3+)and characteristic orange-red emission of Sm^(3+)can be effectively tuned by changing the ratios of PO^(3−)_(4)/VO^(3−)_(4) in Gd(P_(x)V_(1−x))O_(4):1 at%Sm^(3+),1 at%Bi^(3+),and the energy transfer process among VO^(3−)_(4),Sm^(3+),Bi^(3+) also can be adjusted.Based on this,warm white light emitting can be realized by further optimizing the doping concentration of Sm^(3+) in the phosphors.At 423 K,the PL intensity of Gd(P_(0.7)V_(0.3))O_(4):2 at%Sm^(3+),1 at%Bi^(3+) remains~84.3%of the initial value at 293 K,while the measured quantum efficiency is 67.8%.EL spectrum analysis results of the fabricated white light emitting diode(wLED)based on a 310 nm UV-chip and Gd(P_(0.7)V_(0.3))O4:2 at%Sm^(3+),1 at%Bi^(3+)phosphors imply low correlated color temperature(3132 K)and appropriate color-rending index(R_(a)=82.7).These results demonstrate that Gd(P_(0.7)V_(0.3))O4:2 at%Sm^(3+),1 at%Bi^(3+)is a good candidate for manufacturing UV-activated warm white light emitting diodes.展开更多
The widespread applications of lanthanide-doped materials have fuelled a growing demand for precise control over the luminescence characteristics of these materials.However,the limitation imposed by concentration quen...The widespread applications of lanthanide-doped materials have fuelled a growing demand for precise control over the luminescence characteristics of these materials.However,the limitation imposed by concentration quenching remains a major obstacle in achieving efficient luminescence from lanthanide-doped materials.Herein,a novel strategy utilizing Sc_(2)O_(3):Ln^(3+) microflowers to enable confined energy migration in both microscopic quasi-zero-dimensional(0D)and mesoscopic twodimensional(2D)multi-coupling systems is proposed to overcome the concentration quenching limit of lanthanide emitters and achieve a remarkable doping amount of 48.14%on a single particle without resorting to complex core/multishell structure.Mechanistic studies reveal that the multi-confinement structure effectively restricts the range of energy migration and significantly reduces excitation energy migration to defects.Based on these highly doped Sc_(2)O_(3) microflowers,full spectrum and power-dependent tunable multi-color lanthanide emission in a single particle is successfully achieved.Furthermore,the 2D-encoded patterns derived from these microflowers hold great promise for anti-counterfeiting applications.Our findings emphasize the multi-coupling of confined quasi-0D&2D energy migration within a well-designed structure,providing valuable insights into concentration quenching mechanisms.This also opens up new opportunities for multi-level anti-counterfeiting systems and information security.展开更多
Mechanoluminescence has attracted increasing attentions because it can convert the kinetic energy during human daily motions into light to be used in sensors and displays. However, its practical applications are still...Mechanoluminescence has attracted increasing attentions because it can convert the kinetic energy during human daily motions into light to be used in sensors and displays. However, its practical applications are still hindered by the weak brightness and limited color while under large forces. Herein, we developed novel piezoluminescent devices(PLDs) which could effectively emit visible light under low pressing forces through the stress-concentration and enhancing deformation on the basis of carefully-designed array structures. The emitting colors were also tunable by using bilayer luminescent film under different pressures. This work not only provides a new strategy to effectively harvest mechanical energy into light,but also presents a scalable, low-cost and color-tunable PLD which shows great potentials in various applications such as luminescent floors, shoes and stress-activated displays.展开更多
Seeking pure organic functional luminescent materials that are processed from green, low-cost, and sustainable resources remains a challenging but beneficial task. As an abundant natural polymer composed of crosslinke...Seeking pure organic functional luminescent materials that are processed from green, low-cost, and sustainable resources remains a challenging but beneficial task. As an abundant natural polymer composed of crosslinked phenol ether units, lignin is a potential source of organic luminescent material because of the presence of extensive aromatic fragments. In the present work, a remarkable afterglow involving room-temperature phosphorescence(RTP) was achieved via simply embedding alkalized lignin into polyvinyl alcohol(PVA) matrix, and an ultralong luminescence lifetime of more than 160 ms was observed. More importantly, our study revealed that small fragments of hydrolyzed lignin(named LA-H) bearing extensive phenolic oxygen anions were the effective luminescent species. When embedded into a PVA matrix, LA-H showed remarkably high luminescence quantum yield and long lifetime of RTP emission compared with those of unprocessed lignin. Additionally, the various phenol oxygen anion moieties endowed LA-H with an excitation-dependent characteristic: the color-tunable RTP could be simply tuned from a maximum emission wavelength of 434–532 nm via altering the excitation wavelength. Thus, the color-tunable afterglow of emissive LA-H could be facilely obtained with a yield up to 38.4% using simple acid hydrolysis of lignin without other complex synthesis procedures. This work opens new avenues in the large-scale preparation of low-cost and sustainable pure organic RTP materials.展开更多
基金supported by the National Natural Science Foundation of China(No.22376111)Shandong Provincial Natural Science Foundation(No.ZR2024YQ026)+2 种基金for Excellent Young Scholars,Taishan Scholar Foundation of Shandong Province(No.tsqn202408237)Youth Innovation Team Project for Talent Introduction and Cultivation in Universities of Shandong Province(No.096-1622002)the Research Foundation for Distinguished Scholars of Qingdao Agricultural University(No.663-1117015)。
文摘In recent years,cellulose-based fluorescent polymers have received considerable attention.However,conventional modification methods face challenges such as insolubility in most solvents,fluorescence instability,and environmental risks.In this study,a novel biosynthesis strategy was developed to fabricate fluorescent cellulose by adding fluorescent glucose derivatives to a bacterial fermentation broth.The metabolic activity of bacteria is utilized to achieve in situ polymerization of glucose and its derivatives during the synthesis of bacterial cellulose.Owing to the structural similarity between triphenylamine-modified glucose(TPA-Glc N)and glucose monomers,the TPA-Glc N were efficiently assimilated by the bacterial cells and incorporated into the cellulose matrix,resulting in a uniform distribution of fluorescence.The fluorescence color and intensity of the obtained cellulose could be adjusted by varying the amount of the fluorescent glucose derivatives.Compared to the fluorescent cellulose synthesized through physical dyeing,the fluorescence of the products obtained by in situ polymerization showed higher intensity and stability.Furthermore,fluorescent bacterial cellulose can be hydrolyzed into nanocellulose-based ink,which demonstrates exceptional anti-counterfeiting capabilities under UV light.This biosynthesis method not only overcomes the limitations of traditional modification techniques but also highlights the potential of microbial systems as platforms for synthesizing functional polymers.
基金financially supported by the National Natural Science Foundation of China (No.21301046)
文摘Color-tunable phosphors Sr0.94MoO4：xEu^3＋, （0.06 - x）Tb^3＋ were synthesized rapidly by microwave ra- diation method with active carbon particle as microwave absorbent. The synthesized phosphors were investigated by X-ray powder diffraction （XRD） and fluorescence spec- trophotometer. The effects of the ratio of Eu^3＋ and Tb^3＋ on the phase structure and luminescent properties of the phos- phors were discussed. The results show that Eu^3＋,Tb^3＋-doped samples can be well indexed to the pure tetragonal scheelite- type SrMoO4, indicating that Eu^3＋ and Tb^3＋ are effectively doped into the SrMoO4 host lattices. The as-synthesized Sro.94MoO4：xEu^3＋,（0.06 - x）Tb^3＋ phosphors have two luminescent centers （Eu^3＋ and Tb^3＋）, which can show red and green emissions under ultraviolet light excitation, respec- tively. Doping concentration of Eu^3＋ and Tb^3＋ has great effect on the intensity of emission peaks and the chromaticity of the samples, and the full color between green and red light can be achieved by adjusting the relative concentration of Eu^3＋ and Tb^3＋.
基金Project supported by the National Natural Science Foundation of China(11864038)Natural Science Foundation of Gansu Province of China(18YF1NA104)+1 种基金the Scientific Research Projects of Gansu Colleges and Universities(2017A-009)Undergraduate Innovation Enhancement Program of Northwest Normal University (NWNU2019KT234,NWNU2019CX167)。
文摘A self-luminescence KYb3 F10 material was obtained via a mild hydrothermal method.Its structure,morphology and the corresponding luminescence properties were studied.There is a self-luminesce nce based on the effective recombination of electron and hole on surface defects or electronic centers in KYb3 F10.The pH values have significant impact on crystallinity and self-luminescent intensity of target products.With the introduction of Tb3+and Eu3+into KYb3 F10 matrix,a series of color-tunable emission can be achieved.Simultaneously,Tb3+and Eu3+can also affect the self-luminescent intensity of host slightly.Although there is no obvious energy transfer between host and activators,Tb3+has a distinct sensitive effect on Eu3+ascribed to the energy transfer between Tb3+and Eu3+.In addition,the thermal stability was carefully investigated,which demonstrate the materials can be as a candidate in fluorescent lamps and displays.
基金Project supported by the Gansu Industry and Information Technology Committee(773000054000001)the Fundamental Research Funds for the Central Universities(lzujbky-2014-37)+1 种基金Specialized Reserch Fund for the Doctoral Program of Higher Education(20120211130003)the National Natural Science Foundation of China(51372105)
文摘A series of color-tunable KLaSiO4：Ce3＋,Mn2＋phosphors were successfully prepared and the luminescent properties were investigated. Upon excitation at 290 nm, the emission spectra of KLaSiO4：Ce3＋,Mn2＋phosphors included a blue emission band and a red emission band. Increasing the doping concentration of Mn2＋ions, the red emission was strengthened considerably, and the blue emission of Ce3＋ was reduced, owing to the efficient energy transfer. The composition optimized KLa0.96SiO4：0.02Ce3＋,0.02Mn2＋sample exhibited the white light emission brightly with the chromaticity coordinates of （0.331, 0.337）. Therefore, KLaSiO4：Ce3＋, Mn2＋could be used as a white phosphor candidate for white light-emitting diodes devices.
文摘An efficient color-tunable hybrid white organic light-emitting diode is demonstrated with double interlayers of 2,7-bis(carbazol-9-yl)-9,9-ditoylfluo- rene/2-(diphenylphosphoryl) spiroflu-orene (DMFL-CBP/SPPO1) inserted between blue fluorescent and yellow phosphorescent-emitting layers, and exhibits Commission Internationale de l’Eclairage (CIE1931) ranging from warm white (0.4368, 0.4497) to cool white (0.2781, 0.2896) with driving current density from 0.2 to 40 mA/cm2. The recombination of singlet and the triplet excitons in blue fluores-cent-emitting layer and yellow phosphorescent-emitting layer, respectively, can be modulated by both the thickness of these double interlayers and the applied current densities.
文摘Using a color-tunable organic light-emitting diode (CT-OLED) can accord with the circadian cycle of humans and realize healthy lighting. The variation range of the correlated color temperature (CCT) is an important parameter to measure the performance of CT-OLEDs. In this paper, the effect of changing the utilization of phosphorescent materials and the position of the recombination zone (RZ) in the device are investigated by changing the thickness of the emissive layer (EML) and the doping ratio of the host and vip materials. The results show that reducing the red phosphorescent material and improving the blue phosphorescent material can affect the change direction of CCT, but it is not enough to expand the span of CCT (ΔCCT). It is more conducive to improving ΔCCT by more reasonable regulation of the position of the main RZ in EML and the energy transfer from the blue sub-EML to the red sub-EML. Device D obtains the best electro-optic and spectral characteristics, in which the maximum ΔCCT is 5746 K (2661 - 8407 K) as the voltage changes from 3.75 V to 9.75 V, the maximum current efficiency and luminance reach 18.34 cd·A<sup>-1</sup> and 12,100 cd·m<sup>-2</sup>, respectively.
文摘The color-tunable white organic light-emitting diode (CT-WOLED) with wide correlation color temperature (CCT) has many advantages in optimizing the artificial light source to adapt to the human physiological cycle. The research on the change trend of CCT and the law of extending the change range of CCT will help to further improve the performance of this kind of device. The present work fabricated a series of CT-WOLED devices with a simple structure, which are all composed of two ultra-thin phosphor layers (PO-01 and Flrpic) and a spacer interlayer. The yellow interface exciplex (TCTA/PO-T2T) formed between the spacer layer (PO-T2T) and transmission material (TCTA) in EML will decrease the CCT value at low voltage. The relationship between the energy transfer in EML and CCT change trend is investigated by adjusting the interface exciplexes and the thickness of the interlayer or the phosphor layer in devices A, B and C, respectively. The results demonstrate that a simple OLED device with an interlayer inserted between two ultra-thin phosphor layers can achieve a wider CCT span from 3359 K to 6451 K at voltage increases from 2.75 V to 8.25 V. .
文摘Four kinds of bis(N-alkylsalicylaldiminato) zinc(II) complexes were synthesized, and their molecular structures were determined by FT-IR and elemental analysis. Their photoluminescence properties were determined, which indicated that they could emit strong fluorescence varying from blue to yellow to reddish orange depending on their different molecular structures. They had good thermostability, solubility and film forming capability, and can be used as organic lectroluminescent materials. These new complexes may afford the feasibility to realize full-color display with materials based on similar molecular structures.
基金supported by the National Natural Science Foundation of China (22175149)the Natural Science Foundation of Hunan Province (NSFH 2021JJ30661)。
文摘Achieving color-tunable room-temperature phosphorescence(RTP),especially including blue RTP from a single-component polymer still faces a formidable challenge.Herein,we wisely choose conformation-dependent phenothiazine with trifluoromethyl substituent as the side group of the phosphor monomer(Cz PT)and then copolymerize it with N-isopropylacrylamide(NIPAM)through photopolymerization to obtain polymers PPCz PTs.Time-dependent color-tunable phosphorescence from unusual quasi-equatorial(eq)to quasi-axial(ax)conformers are obtained,and the RTP color changes from orange(550 nm)to blue(470 nm)with phosphorescence lifetime up to 0.96 s.The theoretical calculations confirm that the quasi-axial conformer is the preferred structure that facilitates the formation of intramolecular hydrogen bonds on the trifluoromethyl group.The EPR spectra illustrate that the persistent UV irradiation generates radical cations to induce the conformational transitions first,followed by photopolymerization immobilizing the ax conformation in PPCz PTs.Applications of data encryption and anti-counterfeiting are fabricated to show prompt and delayed multicolor information.This work affords a simple and feasible avenue for two-dimensional color tunable room temperature phosphorescence from a single-component polymer.
基金supported by the National Natural Science Foundation of China (92256304, 21975119)the China Post-doctoral Science Foundation (2022M710020)。
文摘Chiral B,N-doped polycyclic aromatic hydrocarbons with circularly polarized luminescence(CPL) and small full-width at halfmaxima(FWHM) are promising multiple resonance(MR) emitters for CP organic light-emitting diodes(CP-OLEDs).This work presents a pair of chiral MR enantiomers,P/M-o[B-N]_(2)N_(2),featuring B–N bonds incorporated within a[7]-helicene skeleton.These enantiomers exhibit narrow 0-0 and 0-1 electronic transition bands,whose relative intensity can be fine-tuned by increasing doping concentrations,resulting in redshifts of the emission peak from 542 to 592 nm.The enantiomers show mirrorsymmetric CPL spectra with an asymmetry factor(|g_(PL)|) of 1.0×10^(-3).The hyperfluorescent CP-OLEDs with double-sensitized emitting layers display a FWHM of 33 nm,an external quantum efficiency of 25.1%,and a|g_(EL)|factor of 7.7×10^(-4).Notably,the CP-OLEDs realize color-tunable CP electroluminescence peak from 553 to 613 nm by regulating the vibrational coupling.This work provides a novel concept for the design of helical CP-MR materials and CP-OLEDs,highlighting their potential for future applications in advanced optoelectronic devices.
基金supported by the Natural Science Foundation of Fujian Province(2017J01746)。
文摘In this work, novel phosphors Na5Gd(WO4)4: Tb^3+/Yb^3+ and Na5Gd(WO4)4: Tb^3+/Er^3+/Yb^3+ phosphors were synthesized by the solid state reaction method. The photoluminescence properties were investigated. The introduction of Er^3+ to NGW: Tb^3+/Yb^3+ was used to modify the chromaticity coordinates, then providing a good color tunable property. The change in the chromaticity coordinates induces the shift of emission color from yellow-green to blue-green for NGW: Tb^3+/Er^3+/Yb^3+ as the temperature increases. All the results indicate that the NGW: Er^3+/Tb^3+/Yb^3+ phosphors may be used as optical temperature sensing materials.
基金financially supported by the National Natural Science Foundation of China(Nos.51072207 and 61275208)the Shanghai Natural Science Foundation(No.11ZR1441500)Li acknowledges the financial support from National Youth Natural Science Foundation of China(No.61108062)
文摘A tunable luminescence from red to blue in Eu-doped mesoporous AIPO4 glass is achieved by adjusting the annealing temperature. With increasing annealing temperature, the increased Eu^3＋ ions reduction changes the luminescence of the obtained glass. The abnormal reduction of Eu^3＋ to Eu^2＋ occurs in A1PO4 mesoporous glass at relative low annealed temperatures from 600 to 800 ~C in air. The presence of Eu^2＋ ions, which are reduced from Eu^3＋ by hole-electron pairs, is revealed by XPS spectra. Our results indicate the mesoporous AlPO4 glass is a suitable matrix to incorporate Eu ions as the tunable luminescent light sources or LEDs.
基金Fundamental Scientific Research Business Expenses of Central Universities,Grant/Award Number:2342021DUT21ZD211。
文摘Nonconjugated polymer dots(PDs)without largely conjugated structures entitle their advantages such as environment friendliness,nontoxicity,and intrinsic fluorescence.However,color-tunable PDs remain a challenge.Herein,polyvinyl pyrrolidone(PVP)and ascorbic acid(AA)are used to synthesize nonconjugated PDs,namely,PA PDs with intensive blue emission.The introduction of a third component,m-phenylenediamine(MPD),redshifted the emission to green.The asprepared color-tunable blue to green emissive PDs exhibit excellent properties,whether in solution or in solid state,originated from the mechanism of clusteringtriggered emission(CTE)induced by the overlap of electron-rich atoms,the strong inter/intrachain interaction.The quantum yields of blue and green PDs reached up to 15.07%and 28.22%,respectively.Furthermore,PA PDs were successfully applied to the highly efficient photocatalytic degradation for dyes:methylene blue(MB)and methyl orange(MO)were degraded by 89.9%and 93.8%within 20 min under visible light,respectively.
基金National Natural Science Foundation of China,Grant/Award Numbers:22101162,92261114。
文摘Ionically bonded organic metal halide perovskite-like luminescent materials,which incorporate organic cations and metal halides,have emerged as a versatile multicomponent material system.However,these materials still face challenges in terms of low phosphorescence quantum yields and limited long persistent luminescence(LPL)colors.Herein,we present the design and synthesis of an intraligand chargetransfer organic-based metal halide perovskite-like material,in which organic cations form a compact supramolecular hydrogen-bonded organic framework(HOF)structure,exhibiting crystallization-induced phosphorescence emission of ligand,while metal halides form a unique two-dimensional(2D)structure that displays intrinsic self-trapped excitons(STE)emission under the radiation of UV light.Notably,the metal halide hybrid is found to exhibit enhanced phosphorescent photoluminescence efficiency of up to 81.05%and tunable LPL from cyan to orange compared to the pristine organic phosphor,due to the structural distortion and scaffolding effects of 2D metal halides as well as a well-packed HOF structure.Optical characterizations and theoretical calculations reveal that charge transfer from organic cations and halogen to ligand as well as STE from inorganic layers are responsible for the tunable LPL.Meanwhile,the high-efficiency phosphorescent quantum yield is attributed to stronger hydrogen bond stacking as well as structural distortion of metal halogen bands.Thus,the obtained LPL provides potentials in anti-counterfeiting,security systems,and so on.
基金supported by the National Natural Science Foundation of China(11464017,11864015)the Scientific Research Foundation for Universities from the Education Bureau of Jiangxi Province(GJJ170490)+1 种基金Foundation of Natural Science Funds for Distinguished Young Scholar of Jiangxi Province(20171BCB23064)the Science and Technology Major Project of Jiangxi Province(20165ABC28010).
文摘Investigation on the bright and stable upconversion(UC)phosphors with multicolor emissions is fundamental and significant for the frontier applications of display and tempe rature probe.He re,dive rse emitting colors with blue,cyan and yellowish green,which are caused by the energy transfer and crossrelaxation processes,are obtained by altering Er^3+,Tm^3+and Yb^3+concentrations in Er3+singly,Er^3+-Tm^3+-Yb^3+co-and tri-doped double perovskite La2ZnTiO6(LZT)phosphors synthesized by a simple solid-state reaction.In addition,excellent infrared emission at 801 nm located at"first biological windo w"is collected in Tm^3+-Yb^3+co-doped phosphors.Meanwhile,the temperature sensing properties based on the thermally coupled levels((^2H11/2)/(^4S3/2))of Er3+ions were analyzed from 298 to 573 K of LZT:0.15 Er^3+/0.10 Yb^3+phosphor,demonstrating that the maximal sensitivity value is about56×10^-4 K^-1 at 448 K.All these results imply that this kind of UC material has potential applications in display,bioimaging and optical device.
基金Project supported by the National Natural Science Foundation of China(51972181,61705231)Major Basic Research Projects of Shandong Natural Science Foundation(ZR2018ZB0650)+2 种基金China Postdoctoral Science Foundation(2015M580573)High Quality Course Construction Project of Graduate Education in Shandong Province(SDYKC18051)Postgraduate Tutor Ability Improvement Project of Shandong Province(SDYY17179)。
文摘A series of single phase,warm white light emitting phosphors,Gd(P_(x)V_(1−x))O_(4):y at%Sm^(3+),with 1 at%Bi^(3+) doping concentration were synthesized by high temperature solid state method in this work.The experimental results indicate broadband cyan emission of Bi^(3+)and characteristic orange-red emission of Sm^(3+)can be effectively tuned by changing the ratios of PO^(3−)_(4)/VO^(3−)_(4) in Gd(P_(x)V_(1−x))O_(4):1 at%Sm^(3+),1 at%Bi^(3+),and the energy transfer process among VO^(3−)_(4),Sm^(3+),Bi^(3+) also can be adjusted.Based on this,warm white light emitting can be realized by further optimizing the doping concentration of Sm^(3+) in the phosphors.At 423 K,the PL intensity of Gd(P_(0.7)V_(0.3))O_(4):2 at%Sm^(3+),1 at%Bi^(3+) remains~84.3%of the initial value at 293 K,while the measured quantum efficiency is 67.8%.EL spectrum analysis results of the fabricated white light emitting diode(wLED)based on a 310 nm UV-chip and Gd(P_(0.7)V_(0.3))O4:2 at%Sm^(3+),1 at%Bi^(3+)phosphors imply low correlated color temperature(3132 K)and appropriate color-rending index(R_(a)=82.7).These results demonstrate that Gd(P_(0.7)V_(0.3))O4:2 at%Sm^(3+),1 at%Bi^(3+)is a good candidate for manufacturing UV-activated warm white light emitting diodes.
基金supported by the National Natural Science Foundation of China(92361202,12204481)the Fund of Fujian Science&Technology Innovation Laboratory for Optoelectronic Information(2020ZZ114,2022ZZ204)+3 种基金the China Postdoctoral Science Foundation(2023M733498,2024T170925)the Natural Science Foundation of Fujian Province(2022J05102)the National Key Research and Development Program of China(2022YFB3503704)the Self-deployment Project Research Program of Haixi Institutes,Chinese Academy of Sciences(CXZX-2022-GS01).
文摘The widespread applications of lanthanide-doped materials have fuelled a growing demand for precise control over the luminescence characteristics of these materials.However,the limitation imposed by concentration quenching remains a major obstacle in achieving efficient luminescence from lanthanide-doped materials.Herein,a novel strategy utilizing Sc_(2)O_(3):Ln^(3+) microflowers to enable confined energy migration in both microscopic quasi-zero-dimensional(0D)and mesoscopic twodimensional(2D)multi-coupling systems is proposed to overcome the concentration quenching limit of lanthanide emitters and achieve a remarkable doping amount of 48.14%on a single particle without resorting to complex core/multishell structure.Mechanistic studies reveal that the multi-confinement structure effectively restricts the range of energy migration and significantly reduces excitation energy migration to defects.Based on these highly doped Sc_(2)O_(3) microflowers,full spectrum and power-dependent tunable multi-color lanthanide emission in a single particle is successfully achieved.Furthermore,the 2D-encoded patterns derived from these microflowers hold great promise for anti-counterfeiting applications.Our findings emphasize the multi-coupling of confined quasi-0D&2D energy migration within a well-designed structure,providing valuable insights into concentration quenching mechanisms.This also opens up new opportunities for multi-level anti-counterfeiting systems and information security.
基金supported by the National Key R&D Program of China (2016YFA0203302)the National Natural Science Foundation of China (21634003, 51573027, 51673043, 21604012, 21805044, 21875042, 11602058, and 11872150)+3 种基金Shanghai Science and Technology Committee (16JC1400702, 17QA1400400, 18QA1400700, and 18QA1400800)Shanghai Municipal Education Commission (2017-01-07-00-07-E00062)Shanghai Chenguang Program (16CG01)Yanchang Petroleum Group
文摘Mechanoluminescence has attracted increasing attentions because it can convert the kinetic energy during human daily motions into light to be used in sensors and displays. However, its practical applications are still hindered by the weak brightness and limited color while under large forces. Herein, we developed novel piezoluminescent devices(PLDs) which could effectively emit visible light under low pressing forces through the stress-concentration and enhancing deformation on the basis of carefully-designed array structures. The emitting colors were also tunable by using bilayer luminescent film under different pressures. This work not only provides a new strategy to effectively harvest mechanical energy into light,but also presents a scalable, low-cost and color-tunable PLD which shows great potentials in various applications such as luminescent floors, shoes and stress-activated displays.
基金supported by the National Natural Science Foundation of China (21788102, 22125803, 22020102006,21871083, 22101083)Shanghai Municipal Science and Technology Major Project (2018SHZDZX03)+3 种基金‘Shu Guang’ Project supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation (19SG26)the Innovation Program of Shanghai Municipal Education Commission (2017-01-07-00-02 E00010)the Fundamental Research Funds for the Central Universitiesthe China Postdoctoral Science Foundation (2021M691009)。
文摘Seeking pure organic functional luminescent materials that are processed from green, low-cost, and sustainable resources remains a challenging but beneficial task. As an abundant natural polymer composed of crosslinked phenol ether units, lignin is a potential source of organic luminescent material because of the presence of extensive aromatic fragments. In the present work, a remarkable afterglow involving room-temperature phosphorescence(RTP) was achieved via simply embedding alkalized lignin into polyvinyl alcohol(PVA) matrix, and an ultralong luminescence lifetime of more than 160 ms was observed. More importantly, our study revealed that small fragments of hydrolyzed lignin(named LA-H) bearing extensive phenolic oxygen anions were the effective luminescent species. When embedded into a PVA matrix, LA-H showed remarkably high luminescence quantum yield and long lifetime of RTP emission compared with those of unprocessed lignin. Additionally, the various phenol oxygen anion moieties endowed LA-H with an excitation-dependent characteristic: the color-tunable RTP could be simply tuned from a maximum emission wavelength of 434–532 nm via altering the excitation wavelength. Thus, the color-tunable afterglow of emissive LA-H could be facilely obtained with a yield up to 38.4% using simple acid hydrolysis of lignin without other complex synthesis procedures. This work opens new avenues in the large-scale preparation of low-cost and sustainable pure organic RTP materials.
