- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Fabrication and characterization of Ge–Ga–Sb–S glass microsphere lasers operating at $\sim 1.9\,{\rm{\mu }}{\rm{m}}$
摘要： We report the fabrication and characterization of germanium gallium antimony sul?de (Ge–Ga–Sb–S or 2S2G, doped with Tm3+ ions) microsphere lasers operating at ～1.9-μm spectral band. Compared to the chalcogenide glasses that are used in previous microsphere lasers, this 2S2G glass has a lower transition temperature and a higher characteristic temperature. This implies that 2S2G microspheres can be fabricated at lower temperatures and the crystallization problem in the sphere-forming process can be alleviated. We show that hundreds of high-quality microspheres (quality factors higher than 105) of various diameters can be produced simultaneously via a droplet sphere-forming method. Microspheres are coupled with silica ?ber tapers for optical characterizations. We demonstrate that Whispering Gallery mode (WGM) patterns in the 1.7–2.0 μm band can be conveniently obtained and that once the pump power exceeds a threshold, single- and multi-mode microsphere lasers can be generated. For a typical microsphere whose diameter is 258.64 μm, we demonstrate its laser threshold is 0.383 mW, the laser wavelength is 1907.38 nm, and the thermal sensitivity of the microsphere laser is 29.56 pm/?C.
关键词： chalcogenides,whispering gallery modes,microspheres laser
更新于2025-11-25 10:30:42
-
Enhancing photoluminescence of carbon quantum dots doped PVA films with randomly dispersed silica microspheres
摘要： As a kind of excellent photoluminescent material, carbon quantum dots have been extensively studied in many fields, including biomedical applications and optoelectronic devices. They have been dispersed in polymer matrices to form luminescent films which can be used in LEDs, displays, sensors, etc. Owing to the total internal reflection at the flat polymer/air interfaces, a significant portion of the emitted light are trapped and dissipated. In this paper, we fabricate free standing flexible PVA films with photoluminescent carbon quantum dots embedded in them. We disperse silica microspheres at the film surfaces to couple out the total internal reflection. The effects of sphere densities and diameters on the enhancement of photoluminescence are experimentally investigated with a homemade microscope. The enhancement of fluorescence intensity is as high as 1.83 when the film is fully covered by spheres of 0.86 μm diameter. It is worth noting that the light extraction originates from rather the scattering of individual spheres than the diffraction of ordered arrays. The mechanism of scattering is confirmed by numerical simulations. The simulated results show that the evanescent wave at the flat PVA/air interface can be effectively scattered out of the film.
关键词： silica microspheres,light extraction,photoluminescence,PVA films,carbon quantum dots
更新于2025-11-19 16:46:39
-
Hierarchical ZnO microspheres embedded in TiO2 photoanode for enhanced CdS/CdSe sensitized solar cells
摘要： Control of structural and compositional characteristics of photoanodes is a crucial step toward rapid transport of charges and high efficiency loading of dye or quantum dots in case of solar cell application. A hierarchical ZnO microspheres (ZMS) and TiO2 hybrid photoanode film was prepared for improved CdS/CdSe quantum dot sensitized solar cells (QDSCs). The addition of ZMS into TiO2 electrode films resulted in both increased short circuit current density (Jsc) and open circuit voltage (Voc). Such an improvement is ascribed to the increased light harvesting owing to scattering by ZMS and the reduced charge recombination due to the surface modification. TiO2/ZMS hybrid photoanode displays superior charge injection/transport performance due to the ZMS with unique hierarchical structure, providing charge transfer continuity and multiple electron transport channels for timely electron transport. As a result, the Jsc, Voc, and the photovoltaic conversion efficiency (PCE) were all remarkably enhanced with the insertion of hierarchical ZMS though varied appreciably with the amount of ZMS. Thus, the designed TiO2/ZMS heterostructure based QDSCs with an optimizing ZMS ratio of 20 wt% achieved a PCE of 5.99%, which is about 35% increase of the efficiency for the devices without ZMS (4.45%).
关键词： electron transport,ZnO microspheres,charge injection,quantum dot-sensitized solar cells,photoanode,light scattering
更新于2025-11-14 17:04:02
-
Hierarchical TiO <sub/>2</sub> microspheres composed with nanoparticle-decorated nanorods for the enhanced photovoltaic performance in dye-sensitized solar cells
摘要： Hierarchical TiO2 microspheres composed of nanoparticle-decorated nanorods (NP-MS) were successfully prepared with a two-step solvothermal method. There were three benefits associated with the use of NP-MS as a photoanode material. The decoration of nanoparticles improved the specific surface area and directly enhanced the dye loading ability. Rutile nanorods serving as electron transport paths resulted in fast electron transport and inhibited the charge recombination process. The three-dimensional hierarchical NP-MS structure supplied a strong light scattering capability and good connectivity. Thus, the hierarchical NP-MS combined the beneficial properties of improved scattering capability, dye loading ability, electron transport and inhibited charge recombination. Attributed to these advantages, a photoelectric conversion efficiency of up to 7.32% was obtained with the NP-MS film-based photoanode, resulting in a 43.5% enhancement compared to the efficiency of the P25 film-based photoanode (5.10%) at a similar thickness. Compared to traditional photoanodes with scattering layers or scattering centers, the fabrication process for single layered photoanodes with enhanced scattering capability was very simple. We believe the strategy would be beneficial for the easy fabrication of efficient dye-sensitized solar cells.
关键词： electron transport,dye-sensitized solar cells,solvothermal method,Hierarchical TiO2 microspheres,photovoltaic performance
更新于2025-11-14 17:04:02
-
Synthesis of porous NiMo sulphide microspheres for high-Performance dye-sensitized solar cells and supercapacitor
摘要： Novel hierarchical porous NiMoS4 microspheres with high electrochemical performance was successfully prepared using a facile one-step hydrothermal method. The dual application of porous NiMoS4 microspheres in energy harvesting and storage (ie, dye-sensitized solar cells (DSSCs) and supercapacitors (SCs) respectively) is explored. In contrast to NiS2 nanosheets, MoS2 nanosheets and Pt counter electrodes (CEs), the NiMoS4 microspheres CE demonstrated the lowest charge transfer resistance and highest electrocatalytic activity for the I3?/I? redox couple reaction. The NiMoS4-based DSSC showed a high power conversion efficiency (8.9%) even than that of Pt-based DSSC (8.7%) under simulated standard global AM 1.5G sunlight (100 mW cm?2). As an electroactive material for SCs, the assembled NiMoS4//AC asymmetric supercapacitor showed excellent specific capacitance (118.7 F g?1 at 1 A g?1), high energy density of 42.2 Wh kg?1 (with a power density of 799.2 W kg?1), and superior cycling durability with a specific capacitance retention of 79.5% after 9000 cycles at 3 A g?1.
关键词： Asymmetric supercapacitor,Ni-Mo sulfide,Microspheres,Dye-sensitized solar cells
更新于2025-11-14 17:04:02
-
The Size Effect of TiO2 Hollow Microspheres on Photovoltaic Performance of ZnS/CdS Quantum Dots Sensitized Solar Cell
摘要： Size controllable TiO2 hollow microspheres (HMS) were synthesized by a carbonaceous spheres (CS) template method. Based on TiO2 HMS, the ZnS/CdS quantum dots (QDs) were loaded to form a ZnS/CdS@TiO2 HMS photoanode for quantum dots sensitized solar cell (QDSSC). The size effects of TiO2 HMS on photovoltaic performance were investigated, and showed that TiO2 HMS with sizes ~560 nm produced the best short-circuit current density (Jsc) of 8.02 mA cm?2 and highest power conversion efficiency (PCE) of 1.83%, showing a better photovoltaic performance than any other QDSSCs based on TiO2 HMS with size ~330 nm, ~400 nm, and ~700 nm. The improvement of photovoltaic performance based on ~560 nm TiO2 HMS which can be ascribed to the enhanced light harvesting efficiency caused by multiple light reflection and strong light scattering of TiO2 HMS. The ultraviolet-visible (UV-vis) spectra and incident photo to the current conversion efficiency (IPCE) test results confirmed that the size of TiO2 HMS has an obvious effect on light harvesting efficiency. A further application of ~560 nm TiO2 HMS in ZnS/PbS/CdS QDSSC can improve the PCE to 2.73%, showing that TiO2 HMS has wide applicability in the design of QDSSCs.
关键词： titanium dioxide,quantum dots sensitized solar cells,hollow microspheres
更新于2025-11-14 17:04:02
-
Design of Mn-doped CdxZn1-xSe@ZnO triple-shelled hollow microspheres for quantum dots sensitized solar cells with improved photovoltaic performance
摘要： Mn-CdxZn1-xSe@ZnO multi-shelled (including single-shelled, double-shelled, and triple-shelled) hollow microspheres (HMS) were successfully synthesized for application in quantum dots sensitized solar cell (QDSSC). The influence of shell numbers on photovoltaic performance of QDSSC were investigated. The results showed that larger surface area, repeated light reflection and reinforced light scattering can be achieved with triple-shelled HMS, which can improve light harvesting efficiency. Furthermore, midgap state created by Mn-doping in CdxZn1-xSe will facilitate electrons injection and collection from excited CdxZn1-xSe quantum dots (QDs) to ZnO. The multi-shelled effects and Mn-doping finally improve the short-circuit current (Jsc) of Mn-CdxZn1-xSe@ZnO tripled-shelled HMS solar cell to 20.21 mA cm?2, leading to the power conversion efficiency significantly enhanced to 3.39%.
关键词： Zinc oxide,Solar cells,Quantum dots,Hollow microspheres
更新于2025-11-14 17:04:02
-
Mesoporous TiO2-BiOBr Microspheres with Tailorable Adsorption Capacities for Photodegradation of Organic Water Pollutants: Probing Adsorption-Photocatalysis Synergy by Combining Experiments and Kinetic Modeling
摘要： Understanding adsorption-photocatalysis synergy helps advance solar-driven photodegradation of organic wastewater pollutants. To evaluate the synergy, mesoporous TiO2(amorphous)-BiOBr microspheres were facilely synthesized as model photocatalysts and characterized by XRD, SEM, TEM/HRTEM, XPS, nitrogen adsorption-desorption, UV-vis DRS, photoluminescence, and FTIR. The characterizations and photodegradation tests suggested that the composites had both adsorption sites and photocatalysis sites on BiOBr phase, while homogeneously distributed TiO2 in BiOBr microplates tailored the size of BiOBr crystallites. Accordingly, surface areas of the composites spanned from 22 to 155 m2/g and adsorption capacities for methyl orange (MO) ranged from 16 to 54 mg/g, controlled by the TiO2 content. In addition to experiments, kinetic modeling that combined adsorption with photocatalysis was developed and aided elucidating the synergy and quantitatively evaluating the composites with extracted rate constants from experimental data. The rate constant of the composite (Ti/Bi = 0.6) was calculated to be 3 times that of the pure BiOBr. Though adsorption promoted MO photodegradation, the capacity of the composite for MO adsorption and photodegradation decreased dramatically during the cycling tests. Nevertheless, this problem did not happen during photodegradation of rhodamine B and phenol on the composite and photodegradation of MO on pure BiOBr. This was explained by possible accumulation of degradation intermediates on the composite surface. This study provides a useful approach to investigate the adsorption-photocatalysis synergy from the perspectives of experiments and kinetic modeling and implies the necessity of scrutinizing the adverse effects of high levels of adsorption on recyclability of the photocatalysts.
关键词： Organic pollutants photodegradation,Kinetic modeling,TiO2-BiOBr microspheres,Tailorable adsorption capacities,Adsorption-photocatalysis synergy
更新于2025-11-14 17:03:37
-
A new self-made digital slide scanner and microscope for imaging and quantification of fluorescent microspheres
摘要： Objective: A low-cost microscope slide scanner was constructed for the purpose of digital imaging of newborn piglet brain tissue and to quantify fluorescent microspheres in tissue. Methods: Using a standard digital single-lens reflex (DSLR) camera, fluorescent imaging of newborn piglet brain tissue was performed. A computer algorithm available for download was created to detect fluorescent microspheres in the brain tissue slides and to calculate regional cerebral blood flow (rCBF). The precision of the algorithm was tested by comparing with manual counting of the fluorescent microspheres. Finally, bright-field imaging was tested by adding light diffuser film. Results: Cost of the slide scanner was a fraction of the cost of a commercial slide scanner. The slide scanner was able to image a large number of tissue slides in a semiautomatic manner and provided a large field of view (FOV) of 101 mm2 combined with a resolution of 2.9 μm. The mean difference (SD) between manual and automatic counts was in absolute numbers 0.32 (1.5) microspheres ranging from -5 to 5 microspheres per slide. The relative total difference between automatic and manual counts was -3.1%. Conclusions: A slide scanner was constructed and an automatic algorithm to detect fluorescent microspheres in tissue was developed and validated and showed an acceptable difference to “gold standard” manual counting. The slide scanner can be regarded as a low-cost alternative for researchers when digital slide imaging and quantification of fluorescent microspheres are needed.
关键词： Slide scanner,Fluorescence,Bright-field,Microspheres,Microscopy,Cerebral blood flow
更新于2025-09-23 15:23:52
-
Magnetically Recoverable PEI/Titanate@Fe3O4 Photocatalysts: Fabrication and Photocatalytic Properties
摘要： The magnetically separable ternary polyetherimide/titanate@Fe3O4 (PTF) photocatalysts of special heterostructure between magnetite (Fe3O4) microspheres and titanates nanosheets modified by polyetherimide (PEI) were successfully fabricated via a simple facile hydrothermal deposition method. The as-prepared photocatalysts were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscopy and UV-vis diffuse reflectance spectroscopy etc. The results showed that the as-fabricated material had a structure of Fe3O4 microspheres coated with titanates nanosheets modified by PEI. The special interfacial contact between 3D microsphere and 2D nanosheets in the nanoarchitectures was formed via electrostatic attraction. Furthermore, the resulted photocatalysts were tested by degradation reaction of methylene blue under visible light irradiation and demonstrated an enhanced performance than the pure Fe3O4 microspheres, and the photocatalytic activity enhanced with the molar ratio of Fe3O4 microspheres and modified titanate gradually, which was attributed to the expansion of the surface area and the different electrostatic contact between the Fe3O4 microspheres and titanate nanosheets. Moreover, the obtained results revealed the high yield magnetic separation and efficient reusability of PTF-5 (96.7%) over 3 times reuse.
关键词： titanate,Fe3O4 microspheres,recyclability,photocatalyst,polyetherimide
更新于2025-09-23 15:23:52