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Photo-chemically derived Plasmonic Semiconductor Nanocrystals as Optical Switch for Ultrafast Photonics
摘要： Establishing new photonic material with large optical nonlinearity in the near-infrared regime is significant for ultrafast optical science and devices. In this paper, we developed a facile photochemical approach to fabricate covellite CuS plasmonic nanocrystals (NCs) with high chemical stability and strong oxidation resistance under ambient conditions. The photo-chemically derived CuS NCs possess strong absorption in the visible-to-near-infrared optical range caused by the localized surface plasmon resonance effect (LSPR). We further demonstrate superior saturable absorption behavior of CuS NCs with large modulation depth and high damage threshold. By using CuS as an optical switch, a highly-stable mode-locked pulsed laser operating in the telecommunication band with signal-to-noise ratio over 70 dB and pulse duration of 1.57 ps has been achieved. Our results suggest that the photochemical method is an effective technique to fabricate plasmonic NCs, which can be developed as an excellent candidate for ultrafast photonic devices in the visible-to-near-infrared region.
关键词： Optical switch,CuS nanocrystals,Photochemical synthesis,Ultrafast photonics,Plasmonic semiconductor nanocrystals
更新于2025-09-23 15:19:57
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Modular Nanocomposite Films with Tunable Physical Organization of Cellulose Nanocrystals for Photonic Encryption
摘要： Reported herein is the novel achievement of uniform and tunable interference colors of nanocomposite films containing organized cellulose nanocrystals (CNCs) from dynamic hydrogel precursors. Homogeneous and amendable interference colors with broad range are obtained either by stacking the nanocomposite films to adjust the amount of CNCs in the propagation pathway of light or by regulating the rotation angles between the individual films to alter the relative organization of CNCs within the system. Moreover, the precise and controllable patterned CNC composite films with multicolors in one film are facilely fabricated for the first time from the patterned hydrogel precursors. Based on this stacking/rotation-method, these patterned nanocomposite films with tunable interference colors can be further applied as fundamental elements for optical encryption by establishing a ternary-coded decimal system with encoded decimal numerals, paving the way for the development of photonic functional materials based on CNCs.
关键词： nanocomposites,interference colors,cellulose nanocrystals,photonic materials,encryption
更新于2025-09-23 15:19:57
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Morphological control of TiO2 nanocrystals by solvothermal synthesis for dye-sensitized solar cell applications
摘要： TiO2 nanocrystals TETA1, TPRA2, TIPA3, TBUA4, TTBA5, and TBNA6 were prepared using ethanol, 1-propanol, isopropyl alcohol, n-butanol, tert-butyl alcohol, and benzyl alcohol, through the alcohol-based solvothermal method. The morphology, size, and crystallinity of the TiO2 nanocrystals were characterized utilizing transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and high-resolution transmission electron microscopy analyses. These six TiO2 nanocrystals with different morphologies were used as photoanodes in dye-sensitized solar cells (DSSCs) and their cell efficiencies were 8.08 % (TETA1), 8.38 % (TPRA2), 9.18 % (TIPA3), 7.68 % (TBUA4), 7.85 % (TTBA5), and 6.10 % (TBNA6). Among them, the well dispersed rod-shaped one-dimensional TiO2 (TIPA3) photoanode based cell showed the best power conversion efficiency due to its highest dye loading and excellent light-harvesting capacity. This TIPA3 cell demonstrated a fast electron transport rate with suppressed charge recombination which was confirmed from electrochemical impedance spectroscopy.
关键词： dye loading,TiO2 nanocrystals,power conversion efficiency,solvothermal synthesis,dye-sensitized solar cells
更新于2025-09-23 15:19:57
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Probing the Advantageous Photosensitization Effect of Metal Nanoclusters over Plasmonic Metal Nanocrystals in Photoelectrochemical Water Splitting
摘要： Atomically precise metal nanoclusters (NCs)-based photocatalytic systems have garnered enormous attention owing to the fascinating merits including unique physicochemical properties, quantum confinement effect and photosensitization effect, which are distinct from conventional metal nanocrystals (NYs). Nevertheless, systematic comparison between electrons photoexcited from metal NCs and hot electrons from surface plasmonic resonance (SPR) effect of metal NYs in boosting photoelectrochemical water splitting reaction remains blank. Here, we report the strict and comprehensive comparison on the capability of electrons photoexcited from glutathione-capped gold nanoclusters (Aux@GSH) and hot electrons from plasmonic excitation of gold nanoparticles (Au NYs) self-transformed from Aux@GSH to trigger the PEC water splitting reaction under visible light irradiation. The results indicate photoelectrons of Aux NCs trigger more efficient charge transport rate than hot electrons of plasmonic Au NYs in terms of light harvesting and conversion efficiency under the identical conditions. Moreover, charge transfer characteristics in Aux NCs and Au NYs-based PEC systems were established. This work would reinforce our deep understanding on these two pivotal sectors of metal nanomaterials for solar energy conversion.
关键词： photosensitization effect,plasmonic metal nanocrystals,charge transfer,photoelectrochemical water splitting,metal nanoclusters
更新于2025-09-23 15:19:57
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Optical control of layered nanomaterial generation by pulsed-laser ablation in liquids
摘要： Pulsed-laser ablation in liquids capitalizes on combining chemical and optical control to rapidly generate size, composition, and phase-controlled nanostructures, without the need for surfactants. Very high temperatures, which we determined to be ca. (8,400 ± 1,300) K, pressures, and ion densities exist in the laser-induced liquid-confined plasma. These unique conditions, coupled with the rapid cooling during which nanoparticles are formed, permitted access to new extreme regions of materials’ phase diagrams. This way, we produced metastable layered copper and zinc hydroxide-based nanocrystals with interesting physical properties that can serve as precursors for two-dimensional inorganic semiconductor nanomaterials.
关键词： LTE spectra,optical control,electron temperature,layered nanocrystals,Pulsed-laser ablation in liquids,laser-induced plasma
更新于2025-09-23 15:19:57
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Photoluminescence and Raman spectroscopy of silicon thin films grown by laser ablation
摘要： Silicon thin films were prepared by Laser Ablation technique onto fused quartz substrates. The effect of thermal annealing on the silicon films and the pressure and temperature dependence show an unusual behavior of photoluminescence (PL) spectra of the silicon (Si) thin films. An intense PL energy band around 3.0 eV (400 nm) was observed at room temperature after thermal annealing. Raman spectra of the samples showed an asymmetric peak shifted to 517 cm?1; a broadening (7 cm?1) of the phonon line is also observed. These results agree quiet well with the relaxation of the q-vector selection rules for the Raman active optical phonons. The red-shifted asymmetric Raman line shape was fitted by using the phonon-confinement model, in order to estimate the size of the particles constituting the films.
关键词： Photoluminescence,Raman spectroscopy,Si-nanocrystals,Laser ablation
更新于2025-09-23 15:19:57
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Acoustic Vibrations of Al Nanocrystals: Size, Shape, and Crystallinity Revealed by Single-Particle Transient Extinction Spectroscopy
摘要： Acoustic vibrations in plasmonic nanoparticles, monitored by an all-optical means, have attracted significant increasing interest because they provide unique insight into the mechanical properties of these metallic nanostructures. Al nanostructures are a recently emerging alternative to noble metal nanoparticles, because their broad wavelength tunability and high natural abundance make them ideal for many potential applications. Here we investigate the acoustic vibrations of individual Al nanocrystals using a combination of electron microscopy and single-particle transient extinction spectroscopy, made possible with a low-pulse energy, high sensitivity, and probe-wavelength-tunable, single-particle transient extinction microscope. For chemically synthesized, faceted Al nanocrystals, the observed vibration frequency scales with the inverse particle diameter. In contrast, triangularly-shaped Al nanocrystals support two distinct frequencies, corresponding to their in- and out-of-plane breathing modes. Unlike ensemble measurements, which measure average properties, measuring the damping time of the acoustic vibrations for individual particles enables us to investigate variations of the quality factor on the particle-to-particle level. Surprisingly, we find a large variation in quality factors even for nanocrystals of similar size and shape. This observed heterogeneity appears to result from substantially varying degrees of nanoparticle crystallinity even for chemically synthesized nanocrystals.
关键词： quality factor,Al nanocrystals,single-particle transient extinction spectroscopy,acoustic vibrations,nanoparticle crystallinity
更新于2025-09-23 15:19:57
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Surface Engineering of Alla??Inorganic Perovskite Quantum Dots with Quasi Corea??Shell Technique for Higha??Performance Photodetectors
摘要： All-inorganic lead halide perovskites with good surface morphology show substantial prospect for optoelectronic devices. However, the anion exchange of coordinated alkylamine ligands (e.g., oleic acid and oleylamine) can detach ligands and induce more interface trap sites, subsequently to reduce device performance. In this paper, therefore, a simple solution-processed route is presented to synthesize quasi coreshell CsPbBr3formamidinium iodide (FAI = CH(NH2)2I) colloidal quantum dots (CQDs), and then it is applied as the active layer for photodetectors by finely controlling the ligands exchange. The presence of FAI = CH(NH2)2I on CsPbBr3 is confirmed by Fourier transform infrared spectroscopy. As a result, the photodetector ITO/ZnO (100 nm)/CsPbBr3 (150 nm)/Au show an enhanced specific detectivity over 1013 Jones with a responsivity of 19 A W1 under 3 mW cm2 405 nm illumination at 1.5 V. The experimental data show that the enhanced device performance is due to the improved crystallinity and less surface defects of CsPbBr3 CQDs, as the result of less alkylamine ligands is detached during its FAI passivation, thus the charge carriers’ mobility of the film is improved. Therefore, it provides a promising way for high-performance solution-processed all-inorganic CsPbBr3 based optoelectronic devices.
关键词： CsPbBr3 perovskite nanocrystals,solution-processed,surface passivation,recombination process
更新于2025-09-23 15:19:57
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Lead Free, Aqua Stable A3Bi2I9 Perovskites: Crystal Growth and Blue Emitting Quantum dots [A = CH3NH3+, Cs+ and (Rb0.05Cs2.95)+]
摘要： Despite a great success in the rise in the power conversion efficiency of lead-halide perovskite solar cells, the toxicity of lead and the unstable nature of materials are the major concerns for their wide range of implementation at the industrial level. Herein, we have developed large size single crystals (SCs) in HI solution using temperature lowering method and nanocrystals (NCs) in ethanol (EtOH) and toluene (TOL) solvents of A3Bi2I9 perovskites [where, A = CH3NH3+ (MA)+, Cs+ and (Rb0.05Cs2.95)+]. The stability of A3Bi2I9 perovskite is investigated by immersing the SCs for 24 h and pellet for 12 h into water. Moreover, the A3Bi2I9 perovskite NCs displays a promising photoluminescence quantum yield of 17.63% and a longer lifetime of 8.20 ns.
关键词： Pb-Free Perovskites,Crystal Growth,High PLQY,Water Stability,Phase Transition,Nanocrystals,Low Bandgap
更新于2025-09-23 15:19:57
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Embedding of WO3 nanocrystals with rich oxygen-vacancies in solution processed perovskite film for improved photovoltaic performance
摘要： Seeking strategies of promoting the charge separation and transport of the photo-active layer has been always of significance for the development of high-performance optoelectronic devices. We herein demonstrate an effective way of decorating WO3 nanocrystals in perovskite films for boosted photogenerated carriers transport. The WO3 nanocrystals are generated by a simple technique of pulsed laser irradiation in liquid, then introduced into the perovskite film based on the anti-solvent approach. Such decoration is found helpful for the increase of the short-circuit current density (Jsc) of the device, which leads to the increase of the photoconversion efficiency (PCE) from 17.72% to 19.29%. The improved PCE is mainly due to the decoration of the WO3 at the grain boundaries of perovskite films that facilitates the charge transport between the adjacent grains, which is evidenced by the quenching of the film photoluminescence, shortened carrier lifetime, and increased carrier mobility. We thus believe our study provides an effective way of embedding ordinary metal oxides in perovskite films for enhanced optoelectronic performance.
关键词： Hybrid perovskite solar cell,Pulsed laser irradiation in liquid,WO3 nanocrystals,Charge transport,Oxygen-vacancy
更新于2025-09-23 15:19:57