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Controlled Assembly of Upconverting Nanoparticles for Low-Threshold Microlasers and Their Imaging in Scattering Media
摘要： Micron-sized lasers fabricated from upconverting nanoparticles (UCNP) coupled to whispering gallery mode (WGM) microresonators can exhibit continuous-wave anti-Stokes lasing useful for tracking cells, environmental sensing, and coherent stimulation of biological activity. The integration of these microlasers into organisms and microelectronics requires even smaller diameters, however, which raises threshold pump powers beyond practical limits for biological applications. To meet the need for low lasing thresholds and high ?delity fabrication methods, we use correlative optical and electron microscopy to uncover the nanoparticle assembly process and structural factors that determine e?cient upconverted lasing. We show that 5 μm microspheres with controlled submonolayer UCNP coatings exhibit, on average, 25-fold lower laser thresholds (1.7 ± 0.7 kW/cm2) compared to the mean values of the lowest threshold UCNP lasers, and variability is reduced 30-fold. WGMs are observed in the upconversion spectra for TiO2-coated microspheres as small as 3 μm, a size at which optical losses had previously prevented such observations. Finally, we demonstrate that these upconverting microlasers can be imaged and distinguished through tissue-mimicking phantoms. These advances will enable the fabrication of more e?cient upconverting lasers for imaging, sensing, and actuation in optically complex environments.
关键词： self-assembly,nanoparticle,upconversion,anti-Stokes laser,microlaser
更新于2025-09-19 17:13:59
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Tin-(IV) dopant-controlled synthesis of Yb3+/Er3+:NaGdF4 nanocrystals: Morphology transformation and intensified upconversion performance
摘要： Hexagonal Yb3t/Er3t:NaGdF4 nanocrystals codoped with Sn4t ions were produced via an adjustive solvothermal approach. Simultaneous morphology regulation and intensified upconversion (UC) luminescence of Yb3t/Er3t:NaGdF4 nanocrystals were achieved through Sn4t ions doping. Upon introducing Sn4t ions into the NaGdF4 host, a part of the nanocrystals were converted to nanocubes. By optimizing the Sn4t ions doping content to 40 mol%, UC luminescence intensity of the green and red emissions were intensified by 21 and 31 times, respectively. Moreover, the possible mechanisms for morphology transformation and UC luminescence enhancement of Sn4t-doped Yb3t/Er3t:NaGdF4 nanocrystals were discussed elaborately. Additionally, in contrast to the sample fabricated by co-precipitation method, the result indicated that the UC luminescence intensity with 40 mol% Sn4t ions doping was about 2.5 times higher than the former one. This research could be helpful for designing high-performance UC materials and fulfilling their practical applications.
关键词： Sn4t,Upconversion materials,NaGdF4,Upconversion performance,Morphology
更新于2025-09-16 10:30:52
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Ultrasensitive broadband photodetector using electrostatically conjugated MoS2-upconversion nanoparticle nanocomposite
摘要： Hybrid or composite nanomaterials have emerged that demonstrates superior optoelectronic performance over pure nanomaterials that lacks broadband usage, or responsivity, or both, mainly because of the limitation of the collection of photogenerated carriers. We have addressed this problem by using a composite of MoS2 and a multi-photon absorbing lanthanide doped upconversion nanoparticles (UCNPs), that emits in the visible, to make a photodetector (PD) device with ultrahigh broadband responsivity. Single flake MoS2 electrostatically conjugated with UCNPs were used to fabricate the PD device with platinum, and gold contacts. The device was irradiated with UV-to-NIR illumination, at different power density, to study its broadband photosensitivity. Photoresponsivities in excess of 100 AW-1 is easily obtained; a highest responsivity of 1254 AW-1 is reported for 980 nm at 1.0 V bias. An unprecedented normalized gain of 7.12 x 10-4 cm2 V-1, and Detectivity of 1.05 x 1015 Jones (@980 nm, 1V) was obtained which is, to the best of our knowledge, the highest reported till date for this device class. Under vacuum conditions even higher values of these device parameters were obtained, while losing on the response speeds. The photoresponsivity in the nanocomposite followed the trend of the convoluted optical absorption of the individual components. Real application of the PD device was demonstrated using non-laser domestic appliances such as sodium vapour lamp, mobile phone flash light, and air-condition remote controller.
关键词： Nanocomposites,Responsivity,Molybdenum disulphide,Photodetectors,Broadband,Upconversion nanoparticles
更新于2025-09-16 10:30:52
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High-performance upconversion luminescent waveguide using a rare-earth doped microtube with beveled ends
摘要： Upconversion luminescence-based waveguides can achieve optical signal transmission and visible light emission with near-infrared light excitation and their quality is highly dependent on the coupling efficiency between the light and waveguide. Here, a new luminescent waveguide formed by a rare-earth doped microtube with beveled ends was designed to increase the optical coupling efficiency for vertical waveguide-excitation. The beveled end enabled the near-infrared light to effectively couple into the waveguide and produce a visible transmission pattern and directional emission, which was not possible using conventional luminescent waveguides without beveled ends. It was found that the beveled end can not only improve the input and the output signal efficiency, but also control the coupling efficiency and transmission pattern. In particular, a coupling efficiency of B68% could be obtained with the optimized beveled waveguide with a rotation angle of 301. The high optical coupling efficiency and multi-channel luminescent waveguide enabled by the microtube with beveled ends allowed for a deeper understanding of vertical waveguide excitation, and it extends the potential applications of luminescent waveguides for bioimaging and optical communication.
关键词： rare-earth doped microtube,beveled ends,upconversion luminescence,waveguide,optical coupling efficiency
更新于2025-09-16 10:30:52
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Effects of La3+ on the enhancement NIR quantum cutting and UC emissions in Nd3+–Yb3+ co-doped transparent silicate glass-ceramics for solar cells
摘要： Near-infrared (NIR) quantum cutting (QC) and upconversion (UC) emission of Nd3+–Yb3+ co-doped in Si–Al–Ba–La transparent silicate glass-ceramics (SGC) were prepared. Influence of La3+ on the enhancement NIR QC and UC emission intensity of the co-doped Nd3+–Yb3+ in SGC were investigated. Thereby, NIR QC and UC emission intensity of the co-doped Nd3+–Yb3+ were increased strongly with increasing concentration of LaF3 from 5 up to 25 mol. %. The value of NIR QC emission intensity of the co-doped Nd3+–Yb3+ band centered at ~890, 947, 1071, 1339 and 1430 nm is maximized when the concentration of LaF3 reaches 25 mol. %. At the same time, with the increasing concentration of Yb3+, NIR QC emission intensity of the co-doped Nd3+–Yb3+ bands centered at ~890, 1071, 1339 and 1430 nm of Nd3+ and 947 nm of Yb3+ were gradually increased and reaches its maximum at 2.5 mol. % Yb3+, then decreased owing to the self-quenching effect. In addition, NIR QC mechanism and energy transfer (ET) processes between 2F5/2 → 2F7/2 transition of Yb3+ and transitions of Nd3+ are discussed.
关键词： Solar cells,Upconversion,Near-infrared quantum cutting,Nd3+–Yb3+ co-doped
更新于2025-09-16 10:30:52
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Upconversion luminescence of CaF2-SrF2-ErF3 single crystals upon 1.5 μm laser excitation
摘要： In present work, the spectral-luminescent properties of CaF2-SrF2-ErF3 (CaF2-SrF2:Er) single crystals were investigated. The upconversion luminescence (UCL) of CaF2-SrF2: Er in the visible and infrared spectral regions upon excitation of the 4I13/2 level Er3+ ions were studied for the first time. The absolute energy yields of the UCL upon laser excitation at 1.5 μm are determined for CaF2-SrF2:Er. The possible application of fluoride crystals for increasing the efficiency of solar cells was discussed.
关键词： upconversion luminescence,single crystals,solar cells,CaF2-SrF2-ErF3
更新于2025-09-16 10:30:52
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Performance enhancement of bulk heterojunction organic solar cells using photon upconverter
摘要： In this article, we show that significant performance enhancement can be obtained by incorporating a photo upconverter layer in bulk heterojunction organic solar cells (BHJ OSCs). We systematically optimize the photon upconversion process for P3HT:PCBM, PSBTBT:PCBM, PBDTTT-C:PCBM and PTB7-Th:PCBM based BHJ OSCs using a simple numerical model followed by optoelectronic simulations. After verifying the integrated model of upconversion with experimental reports, we analyze each type of BHJ OSC incorporating photon upconversion layer having optimized spectral characteristics and estimate efficiency enhancement of ~30.8% (4.55% → 5.95%), ~24.3% (5.02% → 6.24%), ~28.9% (6.35% → 8.19%) and ~16.9% (10.55% → 12.34%) for P3HT:PCBM, PSBTBT:PCBM, PBDTTT-C:PCBM and PTB7-Th:PCBM based OSCs, respectively. We then show that effect of photon upconversion and localized surface plasmon resonance on the best performing OSC material considered in this work i.e. PTB7-Th:PCBM, is non-linear and predict a performance boost of mere ~2.3% (12.32% → 12.62%) from additional effort (due to plasmon resonance). Finally, we discuss possibility of extending the efficiency of PTB7-Th:PCBM based BHJ OSC beyond 16% using concentrated sunlight and a practically realizable upconverter layer.
关键词： Organic solar cell,Photon upconversion,Bulk heterojunction,Concentrated sunlight
更新于2025-09-16 10:30:52
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Graphene quantum dot-rare earth upconversion nanocages with extremely high efficiency of upconversion luminescence, stability and drug loading towards controlled delivery and cancer theranostics
摘要： The study reported one concept for fabrication of functional graphene quantum dot-rare earth upconversion nanocage. The nanocage exhibits extremely high efficiency of upconversion luminescence, stability and drug loading toward controlled delivery and cancer theranostics.
关键词： Cancer theranostics,Rare earth-based upconversion nanoparticle,Graphene quantum dot,Drug delivery
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing ADVANCES IN BASIC SCIENCE (ICABS 2019) - Bahal, India (7–9 February 2019)] ADVANCES IN BASIC SCIENCE (ICABS 2019) - Upconversion emission of Ag nanoparticles with Er3+/Yb3+ ions in tellurite glasses under 980nm laser excitation
摘要： The light upconversion in Er3+ - Yb3+ doped TeO2 -WO3- Li2O (TWLEY) doped glass containing silver nanoparticles (NPs) has been reported. Tellurite based glasses have been prepared by melt quenching technique with small amount Ag nanoparticles(NPs). The optical excitation is made at 980 nm in resonance with the 2F5/2→2F7/2 transition of Yb3+ ions in glass system. Intense emission bands centered at 525nm, 550nm, and 654 nm were observed corresponding to Er3+ ions transitions. Upconversion fluorescence Intensity of the glasses samples are also observed at 980nm femtosecond laser excitation using two photons microscope. For this green and red colour intensity measurement of the TWLEY with Ag NPs glass sample has been analyzed by intensity histograms. Results show that plasmon enhances upconversion of silver and rare-earth doped glasses may be utilized to explore its potential for multiphoton microscopy.
关键词： Tellurite glasses,Ag nanoparticles,Er3+/Yb3+ ions,980nm laser excitation,Upconversion emission
更新于2025-09-16 10:30:52
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Controlled patterning of upconversion nanocrystals through capillary force
摘要： Lanthanide-doped upconversion nanoparticles (UCNPs) can absorb near-infrared photons and convert them into visible and ultraviolet emissions. These nanomaterials possess extraordinary optical performance and hold potential as active platforms for a variety of technological applications. The ability to fabricate highly ordered nanoparticle-based photonic elements over a large area is of fundamental significance for luminescence tuning. Despite all the efforts made, however, large-area spatial patterning of UCNPs into ordered arrays with high controllability remains a challenge. In this study, we report a high-throughput strategy to pattern optical nanomaterials through the use of polymer microspheres and templated assembly of UCNPs. This technique utilizes capillary force to drive hybrid clusters into the physical template, resulting in large-area, spatially ordered arrays of particles. The findings reported in this work may promote the development of novel nonlinear optical devices, such as solid-state laser arrays, high-density optical storage, and anti-counterfeiting labels.
关键词： self-assembly,rare earths,patterning,upconversion nanoparticles
更新于2025-09-16 10:30:52