Effective Energy Transfer Research Articles

STRUCTURAL AND LUMIENESCENT STUDY OF EUROPIUM (III) DOPED TUNGSTATES

Motivated by the need of new red phosphor for white - light - emitting diodes (WLEDs) application, Eu3+ doped Sc2-xInx(WO4)3 (x = 0, 1, 2) solid solutions were synthesized by high temperature solid - state reaction. Structural and luminescent properties were obtained by using X - ray diffraction (XRD), infrared and photoluminescence spectroscopic techniques. IR spectrum of the ScIn(WO4)3 doped with Eu3+ contains the characteristic vibrations of the WO4 and MeO6 , (Me = Sc, In) polyhedral, building the Sc2(WO4)3 and In2(WO4)3 structures. An effective energy transfer from the tungstate matrix to the active Eu3+ ion was observed. Intense red luminescence was obtained in these samples under excitation at 394 nm using the sharp 7F0 → 5L6 transition of Eu3+. The calculated asymmetric ratio ( 5D0 → 7F2 / 5D0 → 7F1 ) was about 7.5, suggesting that the obtained materials are characterized with distorted environment around the rare earth ion and with high red emission intensity. The prepared ScIn(WO4)3 solid solution demonstrates the highest emission intensity. The obtained chromaticity coordinates of the Eu3+ doped Sc2-xInx(WO4)3 solid solutions were very close to the red standard recommended by National Television Standards Committee (NTSC).

Hexagonal Prism-Shaped AIE-Active MOFs as Coreactant-Free Electrochemiluminescence Luminophores Coupled with Hollow Cu2-xO@Pd Heterostructures as Efficient Quenching Probes for Sensitive Biosensing.

For most self-luminous metal-organic framework (MOF)-involved electrochemiluminescence (ECL) systems, the integration of exogenous coreactants is indispensable to promote ECL efficiency. However, the introduction of a coreactant into an electrolyte would result in poor stability, thereby inevitably affecting analytical accuracy. Herein, by employing aggregation-induced emission luminogens as ligands, we first synthesized one hexagonal prism-shaped MOF that displays robust and steady ECL signal without an exogenous coreactant. Furthermore, adenosine triphosphate (ATP), as the target analyte, can be fixed on the electrode surface directly owing to the strong coordination between Zr4+ and phosphate groups. According to the ECL resonance energy transfer effect, hollow Cu2-xO@Pd heterostructures are conveniently prepared and act as efficient quenching probes. Remarkably, the resultant urchin-like hollow structure could provide more active sites to anchor ATP aptamers, thus enhancing the ECL quenching efficiency. In this manner, an elaborate coreactant-free ECL system was developed to detect ATP, which demonstrates a remarkable detection limit of 0.17 nM, as well as excellent stability and reproducibility. The present work offers significant enlightenment for the further evolution of advanced ECL systems integrated with MOF-based luminophores.

A selective resonance Rayleigh scattering method for determination of iodine by graphene oxide surface molecularly imprinted polyacrylamide probe

A new graphene oxide nanosurface molecularly imprinted polymer (GO@MIP) probe was synthesized by microwave irradiation, using graphene oxide (GO) as the carrier, iodine as the template molecule, acrylamide as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent, azodiisobutyronitrile (AIBN) as the initiator, and acetonitrile as the pore forming agent. The nanoprobe recognizes the iodine, and exhibits significant resonance Rayleigh scattering energy transfer (RRS-ET) effect between iodine as the acceptor and the nanoprobe as donor. When iodine concentration was in the linear range of 0.02–0.5 mmol/L, the decreased RRS intensity was linear to the concentration. And it was used for the determination of iodine in water samples and iodate ions in salt samples.

Fluorescent Carbon Dots with Red Emission: A Selective Sensor for Fe(III) Ion Detection

We present a procedure for the synthesis and purification of p-phenylenediamine-based carbon dots that can be used for the recognition of Fe(III) ions. Carbon dots have an approximately spherical shape with an average size of 10 nm and are composed of a carbonaceous core surrounded by functional groups attached to it, both of which are responsible for their dual fluorescence properties. The emission bands have a different behavior, with a blue band dependent and a red emission independent of the excitation wavelength, respectively. Red emission is appropriate for the detection of ions and other molecules in biological environments because this high wavelength prevents the occurrence of processes such as resonance energy transfer and internal filter effects. In particular, the presence of Fe(III) ions produces an important quenching phenomenon that can be applied to the fabrication of a sensor. The platform is very sensitive, with a detection limit of 0.85 µM, which is within the lowest values reported for this ion, and a high selectivity that is believed to be due to the formation of a specific complex in the ground state through specific interactions of Fe (III) ions with pyridinic and amino groups on the surface of the nanomaterials.

Long-Wavelength Afterglow Emission with Nearly 100% Efficiency through Space-Confined Energy Transfer in Organic-Carbon Dot Hybrid.

Long-wavelength afterglow emitters are crucial for optoelectronics and information security; however, it remains a challenge in achieving high luminescence efficiency due to the lack of effective modulation in electronic coupling and nonradiative transitions of singlet/triplet excitons. Here, we demonstrate an organic-carbon-dot (CD) hybrid system that operates via a space-confined energy transfer strategy to obtain bright afterglow emission centered at 600 nm with near-unity luminescence efficiency. Photophysical characterization and theoretical calculation confirm efficient luminescence can be assigned to the synergistic effect of intermolecular energy transfer from triplet excitons of CDs to singlets of subluminophores and the intense restraint in nonradiative decay losses of singlet/triplet-state excitons via rationally space-confined rigidification and amination modification. By utilizing precursor engineering, yellow and near-infrared afterglow centered at 575 and 680 nm with luminescence efficiencies of 94.4% and 45.9% has been obtained. Lastly, these highly emissive powders enable superior performance in lighting and information security.

Hydrogen Sulfide (H2S)activatable Photodynamic Therapy Against Colon Cancer by tunable FRET Effect.

Developing activatable photodynamic agents is becoming a promising mode for realizing selective photodynamic therapy (PDT) in cancer treatment. However, till now only a few H2S-activatable photodynamic agents have been involved in this field. Here, we fabricated H2S-activatable nano-assemblies (P@TPPCY) for the treatment of colon cancer containing high concentration H2S. The H2S-activatable photosensitizer (TPPCY) was synthesized by covalent conjugation between tetraphenylporphyrin (TPP) and heptamethine cyanine (Cy7), and then TPPCY was encapsulated by an amphiphilic polymer DSPE-mPEG to form P@TPPCY nano-assemblies. We demonstrated that the photosensitizing effect of TPP was efficiently quenched by Cy7 with strong absorption in the NIR region via fluorescence resonance energy transfer (FRET) effect. Interestingly, the FRET effect between Cy7 and TPP was attenuated by the decrease of absorption of Cy7 in the NIR region after the Cy7 reacted with H2S, and then the photosensitizing effect of TPP in P@TPPCY was activated. Strikingly, the P@TPPCY showed efficient H2S-activatable photodynamic therapy (PDT) in vitro against HCT116 cells (human colon carcinoma cell line), thus this work provides a new method for realizing accurate treatment of colon cancer in virtue of high H2S concentration microenvironment.

Low driving voltage and high reliability 1.54 μm electroluminescence from SnO2:Er/p-Si heterostructured devices via energy transfer effect

Low driving voltage and high reliability 1.54 <i>μ</i>m electroluminescence from SnO2:Er/<i>p</i>-Si heterostructured devices via energy transfer effect

Fluorescence and colorimetric rapiddual-signal "on-off-on" switching detection of ascorbic acidbased on TSPP/DCIP.

Afluorescence and colorimetric dual-signal sensing system for the determination of ascorbic acid (AA) in complex media was developed by using 5,10,15, 20-tetrakis(4-sulfonyl) porphyrin (TSPP) as a sensing probe and sodium 2,6-dichloroindophenol (DCIP) as a bridge. A fluorescence resonance energy transfer (FRET) effect occurred when DCIP was added to the TSPP solution, resulting in the quenching of the fluorescence signal of TSPP and a change in the color of the solution from pink to blue. The DCIP in the system reacted with AA in a redoxreaction to produce colorless phenol imine, the color of the solution changed from blue to green causing an obvious colorimetric response, and the TSPP/DCIP sensing system's fluorescence signal restored owing to AA introduced. The fluorescence method for AAshowed good linearity in the ranges 0.08mM ~ 1mM and 1mM ~ 43.6mM with a detection limit of 6.4μM. And the colorimetric method for AAshowed excellent linearity in the range 0.46mM ~ 40.2mM with a detection limit of 76.0μM. Theconstructed "dual-signal" probe in the study has been successfully applied to the detection of AA in practical samples. The method proposed has great potential for practical applications and provides new ideas for the visual inspection of portable measurements.

Effects of Arrhenius activation energy and melting heat transfer on Carreau fluid through a stretching sheet

ABSTRACT This article investigates the effect of activation energy on Carreau fluid flow in the presence of variable thermal conductivity, inclined magnetic field, melting heat transfer, and Soret and Dufour phenomena. A set of suitable similarity transformations is applied for transforming the governing partial differential equations (PDEs) considered for the physical phenomena into non-linear ordinary differential equations (ODEs). We obtained the results by solving the non-linear ODEs numerically which describe the behavior of the velocity, temperature, and concentration profiles of the fluid against the governing parameters and illustrated these graphically. The velocity distribution decreases for angle of inclination while it is increasing against higher melting parameter. The temperature distribution enhances with higher modified Dufour parameter and Prandtl number while it declines for thermal conductivity, activation energy, and melting parameters. The concentration distribution increases for melting parameter, Soret number, and activation energy parameter while decreasing for temperature difference parameter, Schmidt number, and reaction rate parameter. Skin friction, Nusselt and Sherwood numbers are evaluated numerically against the various governing parameters. Accuracy of the present work is illustrated and established through comparison carried out for skin friction versus magnetic parameter with existing results in the literature.

Broadened and enhanced MIR emission in Yb3+/Er3+/Dy3+ triply-doped CaYAlO4 crystal

Yb3+/Er3+/Dy3+ triply-doped CaYAlO4 single crystal was successfully grown to obtain the broadened and enhanced 3 μm MIR emission. The structure characters were studied by XRD measurement. The optical properties and energy transfer mechanism between Yb3+, Er3+, and Dy3+ were investigated according to the measured absorption spectra, emission spectra, and fluorescence decay curves. The absorption spectra show that the triply-doped crystal could be effective pumped by 980 nm due to the introduced of Yb3+ and Er3+. In comparison with Dy3+ singly-doped CaYAlO4 crystal, a broadened and enhanced ∼3 μm MIR emission with a full width at half maximum (FWHM) of 286 nm was obtained due to the fact that there exists effective energy transfer process from Yb3+ and Er3+ to Dy3+. For Yb3+, it serves as an effective sensitized ion. For Er3+, it could be not only used as an effective sensitized ion, but also as a 2.7 μm MIR emission center. For Dy3+, it serves as a deactivating ion to solve the self-termination “bottleneck” effect of Er3+, and more importantly, as an emission center to achieve 3 μm emission. The comprehensive effect is to obtain enhanced and broadened MIR emission in the triply-doped crystal. In addition, the corresponding energy transfer efficiency from Yb3+: 2F5/2 to Dy3+: 6H5/2 is as high as 90 %. Hence, the Yb3+/Er3+/Dy3+: CaYAlO4 crystal could be used as promising medium for MIR broadband tunable laser applications.

Boron Nitride‐Supported Fluorescein Isothiocyanate for Improving Optical Performance and Stability

AbstractOrganic luminogens play an indispensable role in optoelectronic devices, yet there is a pressing need to address their aggregation‐caused quenching (ACQ) and stability. Here we designed and prepared multilayered boron nitride nanosheets/fluorescein isothiocyanate (MBNNSs/FITC) composite phosphors with tunable photoluminescence by controlling the FITC content and annealing temperature. The research results indicate that MBNNSs/FITC with low or high loading of FITC is not conducive to enhancing the emission intensity of FITC, which can be attributed to the fact that low loading leads to a decrease in the content of fluorescent groups, while high loading promotes intermolecular aggregation of FITC dyes. Interestingly, the emission intensity of FITC in MBNNSs/FITC‐6 composite phosphors can be further enhanced by annealing treatment (200 °C), which can be ascribed to the suppression of the ACQ and effective energy transfer from the MBNNSs to the FITC. Moreover, the resultant composite phosphor displays outstanding thermal stability, remarkable photo stability and exceptional water‐resistance. This work provides a new design space for the development of non‐rare‐earth fluorescent materials using organic fluorescent dyes.

When MnSiO3 meets ratiometric fluorescence: A facile, cost-effective ratiometric fluorescent platform based on oxidase-like MnSiO3 nanozyme for versatile Total Antioxidant Capacity (TAC) measurements

The level alterations of antioxidants are highly associated with various oxidative stress-related diseases, food quality and drug safety problems, which enables the reliable and accurate determination of total antioxidant capacity (TAC) become progressively significant. Herein, for the first time, we explored the catalytic effect of MnSiO3 nanozyme with oxidase-like activity towards different fluorescent substrates, and introduced ratiometric fluorescence to MnSiO3-based biosensing. By harnessing MnSiO3-propelled catalytic oxidation of two fluorescent substrates with contrary responses (Scopoletin, SC and o-phenylenediamine, OPD), we constructed a facile, cost-effective ratiometric fluorescent (RF) platform for TAC measurement. In the absence of antioxidants, SC and OPD can be oxidized, and the synergistic effect of fluorescence resonance energy transfer (FRET) and inner-filter-effect (IFE) between SC and oxidized OPD (Ox-OPD) will result in the weak fluorescence of Ox-SC at 465 nm and the strong one of Ox-OPD at 562 nm, respectively. However, the addition of antioxidants will dissociate MnSiO3, generating the recovered high/low fluorescence values of both substrates. Through monitoring the FI465/FI562 changes, the RF analysis of different antioxidants (Cys, AA, GSH) with satisfactory sensitivity is performed and the TAC measurements in diverse real samples (human serums, beverages, and drugs) are successfully accomplished. Moreover, the system demonstrates high selectivity and could compete with the commercial TAC test kits.

Effects of microwave energy transfer on release and degradation of anthocyanins in berry puree

Effects of microwave energy transfer on release and degradation of anthocyanins in berry puree

White light emission in Bi3+/Te4+ co‐doped Cs2SnCl6 for adjustable daily lighting and visible light communication

Abstractns2 ions‐doped lead‐free perovskites have garnered significant attention for their potential in diverse optoelectronic applications, owing to their broad emission characteristics arising from self‐trapped excitons (STEs). Herein, high‐performance white light‐emitting diodes (WLEDs) for intelligent lighting are developed by Bi3+/Te4+co‐doped Cs2SnCl6. Effective energy transfer between the dual STE emissions results in tunable broadband emissions covering the full‐color region. Adjustable WLEDs containing cold‐ and warm‐white lighting are fabricated. The WLEDs have excellent luminescent performances coupled with adjustable correlated color temperatures of 6417 and 3829 K. This versatility allows them to meet lighting demand for different scenarios, which is essential for future WLEDs to achieve healthy lighting. In addition, the excellent white light emission characteristics can also be applied in the visible light communication (VLC) system, achieving a −3 dB bandwidth of 13.3 MHz and opening eye diagrams in the data rate range of 10–60 Mbps. This work represents a significant advancement toward building intelligent health lighting applications and achieving high‐quality light sources for VLC based on lead‐free perovskites.

Broadband Unidirectional Thermal Emission

AbstractDirectional control of far‐field thermal emission plays a key role in effective heat and energy transfer. However, conventional photonic strategies are challenging to concurrently control the polar and azimuthal angle of thermal emission over broadband. Here both polar and azimuthal angles of thermal emission are constrained to narrow ranges over broadband by introducing in‐plane anisotropy combined with magneto‐optical materials in the epsilon‐near‐zero (ENZ) wavelength range. The physical mechanism of tunable perfect absorption/emission is explored by investigating the evolution of multiple topological phase singularity pairs (TPSPs). The structure consisting of a magnetized gradient‐ENZ emitter and anisotropic spacer that exhibits high (&gt;0.8) unidirectional emissivity (θ: 55°–79°, φ: 163.5°–196.5°) in the p‐polarization for a broad range of wavelength (22–26 µm) is demonstrated. The unveiled physics synergizing ENZ, anisotropy, and magneto‐optical properties that support broadband unidirectional thermal emission will bring new opportunities in applications such as thermal camouflaging, thermal photovoltaics, and infrared light sources.

Multiplexed bacterial recognition based on “All-in-One” semiconducting polymer dots sensor and machine learning

The accurate discrimination of bacterial infection is imperative for precise clinical diagnosis and treatment. Here, this work presents a simplified sensor array utilizing “All-in-One” Pdots for efficient discrimination of diverse bacterial samples. The “All-in-One” Pdots sensor (AOPS) were synthesized using three components that exhibit fluorescence resonance energy transfer (FRET) effect, facilitating the efficient integration of multiple discrimination channels to generate specific fluorescence response patterns through a single detection under single-wavelength excitation. Additionally, machine learning techniques were employed to visually represent the fluorescence response patterns of AOPS upon exposure to bacterial metabolites derived from diverse bacterial species. The as-prepared sensor platform demonstrated excellent performance in analyzing eight common bacteria, drug-resistant strains, mixed bacterial samples, bacterial biofilms and real samples, presenting significant potential in the identification of complex samples for bacterial analysis.

A Cr3+-Yb3+ co-doped high-efficiency near-infrared luminescent phosphor for NIR-II light source applications

Phosphor conversion light-emitting diode (PC-LED) technology has become a focal point of research for portable near-infrared light sources in recent years. One of the crucial aspects is to develop phosphor materials that can be effectively stimulated by commercial available blue light. Unfortunately, efficient phosphors in the NIR-II that can be excited by commercial blue light are particularly scarce. In this study, Mg4Ta2O9:0.04Cr3+,0.03Yb3+,0.07Li+ (MTO:0.04Cr3+,0.03Yb3+,0.07Li+) phosphor was synthesized using the high temperature solid phase method, and its emission spectrum covered the first and second near-infrared windows (700–1200 nm). The internal quantum efficiency (IQE) and external quantum efficiency (EQE) are 88.7 % and 45.6 %, respectively, due to the synergistic effect of energy transfer and Li-ion modification. Additionally, the doping of Yb3+ ions and Li+ ions enhances the thermal stability of luminescence. The thermal stability of MTO:0.04Cr3+,0.03Yb3+,0.07Li+ and MTO:0.04Cr3+,0.03Yb3+ is 9.81 % and 14.43 % higher, respectively, than that of MTO:0.04Cr3+,0.03Yb3+ and MTO:0.04Cr3+. To evaluate its potential applications, we developed a prototype PC-LED utilizing MTO:0.04Cr3+,0.03Yb3+,0.07Li+ phosphor as an emission emitter which demonstrated advantages in biomedical imaging, night vision, and non-destructive testing.

Photoluminescence properties of Eu3+ doped La(OH)3 phosphors: Fuel dependent combustion synthesis

In this study, we synthesized La(OH)3:Eu3+ phosphor using the combustion method with diverse fuels—urea, glycine, and dextrose. Through XRD patterns and Rietveld refinement, we confirmed a hexagonal crystal structure with a P63/m space group for all samples. Our analysis also delved into morphological properties and elemental composition, revealing intriguing differences in particle shapes despite similar sizes, depending on the fuel utilized. Interestingly, the PL excitation and emission characteristics remained consistent among the samples, displaying distinct bands. Spectroscopic investigation of Eu3+ activated La(OH)3 exhibits the strong red emission which indicated effective energy transfer among rare earth and host. Notably, when excited at 284/290 nm and 395 nm, the phosphor emitted multicolour bands spanning blue to red regions. However, some challenges and shortcomings were observed related to lanthanum hydroxide such as thermal stability, because at higher temperatures samples decompose easily which can limit their high-temperature applications. Additionally, some more issues are with this material i.e. complexity in synthesis, insolubility in water and ageing and exposure to atmospheric CO2 which can change its composition. Despite these challenges, our research focuses on optimizing and improving all these parameters. Addressing these shortcomings of lanthanum hydroxide can be beneficial for the advancement of applications. This impressive emission spectrum underscores the potential of this synthesized phosphor for lighting and display devices. The consistent photoluminescence features across different fuel variations suggest robustness and versatility, indicating promising avenues for future exploration in lighting technology research.

Tailoring scintillation and luminescence through Co-doping engineering: A comparative study of Ce,Tb Co-doped YAGG and GAGG garnet crystals

The development of scintillators with co-doping mechanisms has received significant attention due to the resulting enhancements in luminescence and scintillation properties. Scintillators such as Ce-doped (Gd,Tb)3(Al,Ga)5O12 have been recognized for their improved performance, attributed to the effective energy transfer between Ce3+ and Tb3+ ions. Nevertheless, the presence of Gd3+ introduced complexities, as its absorption lines strongly overlap with those of Tb3+, thus masking the details of mechanisms of the Tb3+↔Ce3+ energy transfer. This study endeavored to elucidate this mechanism by comparing the luminescence characteristics of Ce,Tb co-doped Y3Al2Ga3O12 (YAGG) and Gd3A2Ga3O12 (GAGG) single crystals. Through detailed photoluminescence spectral analysis, it was discerned that GAGG exhibited a more robust Tb3+↔Ce3+ energy transfer, as evidenced by a marked extension in the decay time of Ce3+ luminescence. Furthermore, GAGG demonstrated superior integrated radioluminescence intensity across all compositions which is a result of efficient energy transfer from Gd3+ to the luminescence centers. Additionally, comparative thermally stimulated luminescence glow curves, revealed distinctive spectral features between YAGG and GAGG, underscoring the complexity of their luminescence mechanisms. This comparative study not only augmented our comprehension of the intricate energy transfer processes in Ce, Tb co-doped garnet scintillators but also underscored the potential for tailored scintillator development through strategic ion co-doping.

High EQE of 43.76% in solution-processed OLEDs operating at a wavelength of 626 nm

Simultaneously achieving high-efficiency, deep-red emission, and solution-processed organic light-emitting diodes (OLEDs) remains a huge challenge. In this work, a thermally activated delayed fluorescent (TADF) material of CzPXZ that exhibits aggregation-induced emission property and a deep-red phosphorescent emitter of Ir(dmppy)(piq)2(od) are developed to build effective energy transfer pathways by dissolving them in a non-polar organic solvent. The electroluminescent emission peaks of CzPXZ:Ir(III)-based OLEDs are located at deep-red 626 nm, demonstrating efficient energy transfer from CzPXZ to the Ir(III) complex. Furthermore, an optimized DPEPO hole-blocking layer is utilized in such Ir(III)-doped OLEDs to enhance the radiative recombination. Therefore, a high external quantum efficiency of 43.76% is achieved for CzPXZ:Ir(III)-based OLEDs. This work sheds light on the great potential of energy transfer from AIE-TADF to red phosphorescent emitters for high-efficiency, solution-processed, deep-red OLEDs.