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Regulating the Phase Separation of Ternary Organic Solar Cells via 3D Architectured AIE Molecules
摘要： An optimized bulk heterojunction (BHJ) interface, certifying enhanced exciton-splitting, charge separation and recombination inhibition, is vastly desired to obtain high power conversion efficiencies (PCEs). Herein, the ternary strategy has been employed to effectively modify the phase separation between the J71:ITIC blend by incorporating a 3D aggregation-induced emission (AIE) material, Tetraphenylethylene (TPE). Hence, as a consequence of improved charge mobility, lower bimolecular recombination and enhanced fill factor (FF), an excellent PCE of 12.16% has been achieved; a 21.23% increment over the PCE of binary devices. Likewise, Flory-Huggins parameter (c ) and surface free energy analysis reveals a high degree of miscibility between J71 and TPE, that leads to a rearrangement at the D-A interface such that TPE settles in between the D and A and thus forces the ITIC away from J71 and out of the mixed phase, indicating relatively higher average acceptor domain purity at the interface and ultimately better FF and PCE for the ternary devices. Likewise, TPE inclusion in various other fullerene and nonfullerene systems also leads to similar results, signifying this to be an effective methodology to boost the PCEs of the organic solar cells, especially for the systems with low FF.
关键词： energy transfer,aggregation-induced emission,3D molecule,ternary organic solar cells,bulk heterojunction interface,phase separation
更新于2025-09-12 10:27:22
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High efficiency dye-sensitized solar cells with <i>V</i> <sub/>OC</sub> – <i>J</i> <sub/>SC</sub> trade off eradication by interfacial engineering of the photoanode|electrolyte interface
摘要： Interfacial modification of the photoanode|electrolyte interface using oleic acid (OA) is thoroughly investigated in this present study. The overall photoconversion efficiency of 11.8% was achieved under the illumination of 100 mW cm?2 with an optical filter of AM 1.5 G. OA molecules were meant to be adsorbed on to the vacant areas of the TiO2 and the OA moieties leached out the aggregated C106 dye molecules from the TiO2 surface. There was a strong spectral overlap between the absorption spectrum of donor (OA) and the emission spectrum of acceptor (C106), leading to effective F?rster Resonance Energy Transfer (FRET) between OA and C106 and suggested an excellent opportunity to improve the photovoltaic performances of DSSCs. UV-vis DRS and UPS analysis revealed that OA molecules created new surface (mid-gap energy) states (SS) in TiO2 and these SS played a major role in the electron transport kinetics. Mott–Schottky analysis of DSSCs under dark conditions was carried out to find the shift in the flat band potential of TiO2 upon OA modification. Surprisingly, no trade off between VOC and JSC was observed after interfacial modification with OA. The dynamics of charge recombination and electron transport at the photoanode|electrolyte interface were studied in detail using electrochemical impedance spectroscopy.
关键词： interfacial engineering,F?rster Resonance Energy Transfer,oleic acid,photoconversion efficiency,dye-sensitized solar cells
更新于2025-09-12 10:27:22
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Aqueous Carbon Quantum Dot-Embedded PC60-PC <sub/>61</sub> BM Nanospheres for Ecological Fluorescent Printing: Contrasting Fluorescence Resonance Energy-Transfer Signals between Watermelon-like and Random Morphologies
摘要： To go beyond the PC60 surfactant structure, the double-layer micelle morphology in water motivates exploration of altered protocols to produce new morphologies. Furthermore, the low photoluminescence quantum yield of aqueous fullerene-based particles encourages high fluorescence to create a light-emitting display. With this in mind, we established new hybrid n-type nanospheres with carbon quantum dot (CQD)-embedded PC60-PC61BM particles, processed using two different protocols. The homogenizer-assisted PC60-CQD-PC61BM resulted in a watermelon-shaped spherical particle, whereas a circular morphology with randomly embedded CQDs was observed in the microwave-treated hybrids. More surprisingly, the watermelon-shaped colloid induced efficient fluorescence resonance energy transfer (FRET) between the CQD and C60 molecules of PC61BM, and the FRET-mediated emission signature diminished gradually as the stripe patterns collapsed. This phenomenon allowed different fluorescent colors in the colloidal printing film. We thereby provided the new carrier dynamics of the particle photonic activities of the developed aqueous PC60-based colloids with the possibility of ecological utilization.
关键词： water-processable organic semiconductor colloids,fullerene-based nanoparticles,fluorescence resonance energy transfer,ecological fluorescent printing,carbon quantum dots
更新于2025-09-11 14:15:04
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Interfacial Energy Transfer in Hollow Double-Shelled TiO <sub/>2</sub> : <i>x</i> %Eu <sup>3+</sup> @SiO <sub/>2</sub> : <i>y</i> %Tb <sup>3+</sup> Nanospheres for Tissue Imaging
摘要： In this paper, hollow double-shelled TiO2:x%Eu3+@SiO2:y%Tb3+ nanospheres (C1-Ti-x/Si-y) were fabricated using carbon spheres as hard template followed by a two-step sol-gel coating process. The results demonstrate that there is strong interaction between inner TiO2 layer and outer SiO2 layer, which can be characterized by the high surface content of Ti-O-Si bonds. The strong interaction makes it possible to achieve efficient energy transfer from Tb3+ to Eu3+ ions through crossing the double-shelled interface. The interfacial energy transfer (IET) efficiency from Tb3+ to Eu3+ions is strongly influenced by the doping concentration of Eu3+ ions whose maximum is determined to be 30.2%. Furthermore, the surface of inner TiO2 layer is modified by the outer SiO2 layer through this strong interaction, which significantly enhances the emission intensity and suppresses the concentration quenching of Eu3+ ions. Under 377 nm excitation, C1-Ti-x/Si-y simultaneously exhibits red and green emissions derived from Eu3+ and Tb3+ ions, respectively. Moreover, by varying doping concentration of Tb3+ and Eu3+ ions, the luminescence color of the samples can be tuned from green to orange and red. The characterization results show that our proposed phosphors may provide potential applications in tissue imaging.
关键词： Multicolor phosphors,Hollow double-shelled nanostructure,Interfacial energy transfer,Concentration quenching suppressed,Surface modification
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Toward Coupling Color Centers in Single Crystal Diamond to Two-Dimensional Materials
摘要： Individual nitrogen vacancy (NV) color centers in diamond are bright, photo-stable, atomic-sized dipole emitters [1]. Consequently, they represent optimal candidates for novel scanning near field microscopy techniques [2]. Here, NV centers form one member of a F¨orster Resonance Energy Transfer (FRET) pair. Due to their broadband emission (> 100 nm), NVs are versatile donors for FRET to systems absorbing in the near infrared spectral range. Highly-promising applications include, e.g., nanoscale imaging of fluorescent molecules or nanomaterials like graphene [2]. Critical parameters for FRET are the NV’s quantum efficiency, charge state stability and NV-sample-distance. Previous experiments used NVs in nanodiamond for FRET [2], however these NVs might suffer from quenching, instability and badly controlled surface termination. We here address this issue by using shallowly implanted NV centers in optimized cylindrical nanostructures [3] used as scanning probes in our homebuilt combination of a confocal and an atomic force microscope. In recent years, two-dimensional materials especially monolayers of semiconducting materials are of major interest in research. Particularly, dichalcogenides like, e.g., tungsten diselenide (WSe2) are promising candidates for a varity of applications [4]. WSe2 emits photons at a wavelength of around 750 nm while absorbing photons below 700 nm [4] which renders WSe2 as a promising FRET partner for NV centers. Here, we present first results towards demonstrating the interaction of NV color centers in single crystal diamond with WSe2. We envisage using quenching of the NV center sued as a donor in FRET in close proximity to the 2D material as a valuable sensing ressource.
关键词： F¨orster Resonance Energy Transfer (FRET),tungsten diselenide (WSe2),nitrogen vacancy (NV) color centers,diamond,two-dimensional materials
更新于2025-09-11 14:15:04
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A multiplexed FRET aptasensor for simultaneous detection of mycotoxins with magnetically controlled graphene oxide/Fe3O4 as single energy acceptor?
摘要： Aflatoxin B1 (AFB1) and fumonisin B1 (FB1) are the most common mycotoxins and often coexist in agricultural products, which are known to be a toxic superposition and even carcinogenic effects on humans. We proposed a multiplexed fluorescence resonance energy transfer (FRET) aptasensor for simultaneous detection of mycotoxins with magnetically controlled graphene oxide (GO)/Fe3O4 as single energy acceptor. CdTe quantum dots emitting green (GQDs) and red (RQDs) fluorescence are modified by aptamers specifically for AFB1 and FB1 and used as dual energy donors. Compared with conventional FRET system based on GO quencher, GO/Fe3O4, a single energy acceptor, can not only quench the fluorescence of aptamer-modified GQDs and RQDs with different emission peaks simultaneously, but also be removed by effective magnetic separation to eliminate the interference of background. In the absence of GO/Fe3O4 nanocomposites, the aptamer modified GQDs and RQDs give off strong fluorescence under ultraviolet radiation. The fluorescence of GQDs and RQDs is quenched when GO/Fe3O4 nanocomposites is added to the system owing to the π–π stacking interaction between GO/Fe3O4 nanocomposites and GQDs- and RQDs-labeled aptamer. However, in the presence of AFB1 and FB1, the binding of aptamers to their specific targets will fold their single stranded structures and hinder the contact between base group in aptamers and GO/Fe3O4, which cause the fluorescence recovery of GQDs and RQDs. With the help of one step of magnetic separation, the supernatants can be collected for fluorescence analysis. After optimization of detection conditions, the developed method had a wider linear range of 10 pg mL?1–100 ng mL?1 for AFB1 and 50 pg mL?1–300 ng mL?1 for FB1 and showed no cross-reactivity with other closely related mycotoxins, respectively. The limit of detection for AFB1 and FB1 are calculated to be 6.7 and 16.2 pg mL?1 based on S/N=3. The detection of mycotoxins has been successfully realized in peanut samples and a new application field of FRET system is expected for various targets.
关键词： aptasensor,fluorescence resonance energy transfer,aflatoxin B1,fumonisin B1,simultaneous detection
更新于2025-09-11 14:15:04
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Hydrothermal Synthesis and Upconversion Properties of About 19?nm Sc2O3: Er3+, Yb3+ Nanoparticles with Detailed Investigation of the Energy Transfer Mechanism
摘要： The Sc2O3: Er3+, Yb3+ nanoparticles (NPs) with the size of about 19 nm were synthesized by a simple oleic acid-mediated hydrothermal (HT) process. X-ray diffraction (XRD), transmission electron microscopy (TEM), upconversion luminescence (UCL) spectra, and decay curves were used to characterize the resulting samples. The Sc2O3: Er3+, Yb3+ NPs made by HT method exhibit the stronger UCL, of which the red UCL are enhanced by a factor of 4, in comparison with those samples prepared by solvothermal (ST) method at the same optimized lanthanide ion concentrations. The UCL enhancement can be attributed to the reduced surface groups and longer lifetimes. Under 980 nm wavelength excitation, the decay curves of Er3+: (2H11/2, 4S3/2) → 4I15/2 and 4F9/2 → 4I15/2 emissions for Sc2O3: Er3+, Yb3+ NPs samples are both close to each other, resulting from the cross relaxation energy transfer from Er3+ to Yb3+, followed by an energy back transfer within the same Er3+-Yb3+ pair. Also, under the relatively low-power density, the slopes of the linear plots of log(I) vs. log(P) for red and green emissions are 2.5 and 2.1, implying the existence of three-photon processes. Our results indicate that Sc2O3: Er3+, Yb3+ NPs is an excellent material for achieving intense UCL with small size in the biological fields.
关键词： Hydrothermal synthesis,Upconversion,Sc2O3,Energy transfer,Er3+/Yb3+
更新于2025-09-11 14:15:04
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Concentration dependent Dy3+ activated LiPbB5O9 phosphor: Structure and luminescence studies for white LED applications
摘要： In this study, distinct concentrations of Dy3t ions (0.04, 0.07, 0.1, 0.4 and 0.7 mol%) doped LiPbB5O9 phosphors were fabricated via solid state reaction technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric studies (TG-DSC) and photoluminescence characterizations were performed to LiPbB5O9:Dy3t phosphors. Photoluminescence excitation and emission spectra were recorded at 576 nm and 349 nm, respectively. The stress, the critical distance (Rc) and energy transfer parameters (Q) between the Dy3t ions were evaluated for all concentrations. To interpret the white light emission ability of the LiPbB5O9:Dy3t phosphor, yellow to blue (Y/B) intensity ratios have been calculated. The decay curves of 4F9/2 level of Dy3t ions were studied. The CIE color co-ordinates and coordinate color temperatures (CCT) were also calculated. From these studies, it is mentioned that LiPbB5O9:0.4Dy3t phosphor is a suitable material for fabrication of WLEDs and laser applications.
关键词： William-Hall analysis,Energy transfer,Lifetime,Photoluminescence,White light
更新于2025-09-11 14:15:04
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Structure of a cyanobacterial photosystem I tetramer revealed by cryo-electron microscopy
摘要： Photosystem I (PSI) functions to harvest light energy for conversion into chemical energy. The organisation of PSI is variable depending on the species of organism. Here we report the structure of a tetrameric PSI core isolated from a cyanobacterium, Anabaena sp. PCC 7120, analysed by single-particle cryo-electron microscopy (cryo-EM) at 3.3 ? resolution. The PSI tetramer has a C2 symmetry and is organised in a dimer of dimers form. The structure reveals interactions at the dimer-dimer interface and the existence of characteristic pigment orientations and inter-pigment distances within the dimer units that are important for unique excitation energy transfer. In particular, characteristic residues of PsaL are identified to be responsible for the formation of the tetramer. Time-resolved fluorescence analyses showed that the PSI tetramer has an enhanced excitation-energy quenching. These structural and spectroscopic findings provide insights into the physiological significance of the PSI tetramer and evolutionary changes of the PSI organisations.
关键词： cyanobacterium,excitation energy transfer,tetramer,Photosystem I,cryo-electron microscopy
更新于2025-09-11 14:15:04
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Quantum Dots Improve Photovoltaic Properties of Purple Membranes under Near-Infrared Excitation
摘要： Purple membrane (PMs), in which the photosensitive protein bacteriorhodopsin (bR) naturally occurs, have photovoltaic properties and are promising for optoelectronic applications. However, PMs cannot effectively absorb light in the NIR spectral region. Semiconductor quantum dots (QDs), which have high two-photon absorption cross-sections in the NIR region, can significantly improve the light sensitivity of PMs by means of F?rster resonance energy transfer (FRET) from QDs to bR inside PMs. The purpose of this study was to improve the photovoltaic properties of PMs by means of FRET from QDs to bR under NIR two-photon excitation. We made the QD-PM complexes and showed high FRET efficiency in them. Finally, we found that the current signal from the QD-PM material was higher than that in the case of PMs alone under NIR excitation. The obtained results clearly demonstrate improvement of the photovoltaic properties of PMs under NIR two-photon excitation due to the FRET from QDs to bR and show the prospect of designing new photosensitive bio-nanohybrid devices.
关键词： Near-Infrared Excitation,F?rster Resonance Energy Transfer,Purple Membranes,Photovoltaic Properties,Quantum Dots
更新于2025-09-11 14:15:04