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Highly stable all-inorganic CsPbBr <sub/>3</sub> nanocrystals film encapsulated with alumina by plasma-enhanced atomic layer deposition
摘要： All-inorganic CsPbBr3 nanocrystals (NCs) have been considered as promising candidates for many optoelectronic applications. However, their perspectives are primarily impeded by the material instability arising from the labile surface and ionic nature of CsPbBr3 NCs. Hence it is high desired to obtain robust CsPbBr3 NCs film for practical applications. Herein, we deposited Al2O3 on NCs film surface for film stabilization by plasma-enhanced atomic layer deposition. The dense Al2O3 film can yield an excellent encapsulation effect, leading to a dramatically improved stability of CsPbBr3 NCs film. This work not only provides a superior technique for NCs film coating but also contributes to address the stability issue of CsPbBr3 NCs.
关键词： PEALD,Encapsulation,Inorganic Materials,Stability,CsPbBr3 Nanocrystals
更新于2025-09-23 15:22:29
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A Visible Light-Near-Infrared Dual-Band Smart Window with Internal Energy Storage
摘要： The integration of electrochromic smart windows with energy storage is an appealing concept for green building development. Herein, we report a dual-band electrochromic energy storage (DEES) window capable of independent control of visible light (VIS) and near-infrared (NIR, solar heat) transmittance with a high internal charge storage. The key design feature is the use of composition-optimized Ta-doped nano-TiO2 nanocrystals as a multifunctional active material to deliver a high charge-storage capability concurrently with high bistability and long-cycle-life electrochromism in three distinct operating modes: (1) the VIS and NIR transparent "bright" mode; (2) the VIS transparent and NIR opaque "cool" mode; and (3) the completely opaque "dark" mode. The independent control of VIS (sunlight) and NIR (solar heat) modulation was successfully demonstrated in a DEES prototype with a high charge-storage capacity of 466.5 mA hr m?2 at 150 mA m?2 of current density.
关键词： nanocrystals,dual-band electrochromic,smart window,energy storage,Ta-doped TiO2
更新于2025-09-23 15:22:29
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The influence of Eu3+ concentration on the spectroscopic properties of YAG:Ti, Eu3+ nanocrystalline luminescent thermometer
摘要： The influence of Eu3+ co-dopant on the luminescent properties of an yttrium aluminum garnet co-doped with titanium and europium ions (YAG: Ti, Eu) nanocrystals has been investigated. This is a continuation of the search for novel materials suitable for luminescence thermometry using an approach based on inorganic nanocrystals co-doped with transition metal ions and lanthanides. The optical response of Ti3+, Ti4+ and Eu3+ ions present in the examined structures was analyzed in a wide range of temperatures. A model of distribution of energy levels of these ions explaining the observed spectra and their dependence on the Eu concentration was proposed. Moreover, the possibility of energy transfers between these ions and their dependence on the concentration of Eu ions and on the temperature was indicated. On this basis, a model was proposed, allowing for the optimization of the maximum sensitivity and the corresponding temperature.
关键词： Titanium,Luminescent thermometry,Europium,Eu3+,Nanocrystals
更新于2025-09-23 15:22:29
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Changes of the absorption cross section of Si nanocrystals with temperature and distance
摘要： The absorption cross section (ACS) of silicon nanocrystals (Si NCs) in single-layer and multilayer structures with variable thickness of oxide barriers is determined via a photoluminescence (PL) modulation technique that is based on the analysis of excitation intensity-dependent PL kinetics under modulated pumping. We clearly demonstrate that roughly doubling the barrier thickness (from ca. 1 to 2.2 nm) induces a decrease of the ACS by a factor of 1.5. An optimum separation barrier thickness of ca. 1.6 nm is calculated to maximize the PL intensity yield. This large variation of ACS values with barrier thickness is attributed to a modulation of either defect population states or of the efficiency of energy transfer between confined NC layers. An exponential decrease of the ACS with decreasing temperature down to 120 K can be explained by smaller occupation number of phonons and expansion of the band gap of Si NCs at low temperatures. This study clearly shows that the ACS of Si NCs cannot be considered as independent on experimental conditions and sample parameters.
关键词： silicon nanocrystals,average lifetime,absorption cross section,photoluminescence decay,nanocrystal distance
更新于2025-09-23 15:22:29
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Engineering Tunable Broadband Near-Infrared Emission in Transparent Rare-Earth Doped Nanocrystals-in-Glass Composites via a Bottom-Up Strategy
摘要： Applications of trivalent rare earth (RE3+)-doped light sources in solid-state laser technology, optical communications, biolabeling, and solar energy management have stimulated a growing demand for broadband emission with flexible tunability and high efficiency. Codoping is a conventional strategy for manipulating the photoluminescence of active RE3+ ions. However, energy transfer between sensitizers and activators usually induces nonradiative migration depletion that brings detrimental luminescent quenching. Here, a transparent framework is employed to assemble ordered RE3+-doped emitters to extend the emission spectral range by extracting photons from a variety of RE3+ ions with sequential energy gradient. To block migration-mediated depletion between different RE3+ ions, a nanoscopic heterogeneous architecture is constructed to spatially confine the RE3+ clusters via a 'nanocrystals-in-glass composite' (NGC) structure. This bottom-up strategy endows the obtained RE3+-doped NGC with high emission intensity (nearly one order of magnitude enhancement) and broadband near-infrared emission from 1300 to 1600 nm, which covers nearly the whole low-loss optical communication window. Most crucially, NGC is a versatile approach to design tunable broadband emission for the potential applications in high-performance photonic devices, which also provides new opportunities for engineering multifunctional materials by integration and manipulation of diverse functional building units in a nanoscopic region.
关键词： luminescence,rare earth doping,broadband emission,nanocrystals-in-glass composite,near-infrared emission
更新于2025-09-23 15:22:29
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A Strategy toward New Low-Dimensional Hybrid Halide Perovskites with Anionic Spacers
摘要： The low-dimensional halide perovskites have received enormous attention due to their unique photovoltaic and optoelectronic performances. Periodic spacers are used to inhibit the growth of 3D perovskite and fabricate a 2D counterpart with layered structure, mostly based on organic/inorganic cations. Herein, by introducing organic anions (e.g., pentanedioic acid (PDA) and hexanedioic acid (HDA) simultaneously), leaf-shaped (Cs3Pb2Br5)2(PDA–HDA) microplates with low-dimensional structure are synthesized. They also exhibit significant photoluminescence (PL) centered at 540 nm with a narrow emission peak. The synthesis of single crystals of Pb(PDA) and Pb(HDA) allows to further clarify the crystal structure of (Cs3Pb2Br5)2(PDA–HDA) perovskite and its structural evolution mechanism. Moreover, the cooperative introduction of dicarboxylic acid pairs with appropriate lengths is thermodynamically favored for the low-dimensional perovskite crystallization. The temperature-dependent PL indicates a V-shaped Stokes shift with elevated temperature that could be associated with the localization of excitons in the inorganic layers between organic dicarboxylic acid molecules. This work demonstrates low-dimensional halide perovskite with anionic spacers, which also opens up a new approach to the growth of low-dimensional organic–inorganic hybrid perovskite crystals.
关键词： photoluminescence,low-dimensional materials,nanocrystals,halide perovskites
更新于2025-09-23 15:22:29
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Photonic Titanium dioxide film obtained from hard template with chiral nematic structure for environmental application
摘要： In the present work, mesoporous TiO2 with a photonic structure was elaborated using cellulose nanocrystals (CNCs) as a biotemplate by two-step hard template methods. This strategy enables to replicate the chiral nematic (CN) structure of the photonic films (biotemplate) in TiO2 films. A series of iridescent CNCs films with different weight ratios of silica/CNCs composite photonic films were prepared via evaporation induced self-assembly (EISA) method. The films showed iridescent color and tuneable Bragg reflection wavelengths by solely changing the ratio between the silica and the CNCs biotemplate. Polarized optical microscopy (POM) performed on hydride SiO2/CNCs films showed a birefringence and typical fingerprint of chiral nematic structure. This birefringence was also observed for TiO2 films obtained using SiO2 films as a hard template, which suggested the transfer of the chiral nematic structure in TiO2 materials. Afterwards, their optical, morphological and electronic properties were studied by scanning electron microscope (SEM), POM, energy-dispersive X-ray spectroscope (EDX) and time resolved microwave conductivity (TRMC). The photocatalytic activities were evaluated by following the phenol degradation using high performance liquid chromatography (HPLC). The results showed that the structuration of the TiO2 film using a chiral nematic SiO2 film as hard template enhances the photocatalytic performance compared to non-structured mesoporous TiO2.
关键词： hard template,cellulose nanocrystals,iridescent film,evaporation induced self-assembly,light harvesting,phenol degradation,chiral nematic structure
更新于2025-09-23 15:22:29
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In-situ synthesis of gold nanocrystals anchored graphene oxide and its application in biosensor and chemical sensor
摘要： This research demonstrated the development of graphene oxide (GO)-gold nanocrystals (AuNCs) composite-modified glassy carbon electrode (GCE) for the sensitive detection of dopamine (DA), uric acid (UA), and 4-aminophenol (4-AP). The GO was synthesized by modified Hummer’s method, which was utilized to prepare GO-AuNCs composites by in situ synthesis method using sodium L(-) malate as a reducing agent. Morphological, X-ray diffraction, and spectral analysis revealed the homogeneous formation of AuNCs with high crystallinity and purity on the GO surface and the sizes of the NCs were decreased with increasing the concentrations of sodium L(-) malate. The optimal GCE/GO-AuNCs sensor exhibited excellent electrocatalytic activity towards the oxidation of DA, UA, and 4-AP. The sensor showed interference-free and selective detection of DA and UA with sensitivities of ca. 30.3 and 17.28 μA/cm2/μM, respectively, and detection limits of ca. 28 and 50 nM, respectively, with wider dynamic ranges, measured by differential pulse voltammetry (DPV) technique. Whereas, it displayed a sensitivity and detection limit of ca. 5.70 μA/cm2/mM and 0.017 nM, respectively, for the detection of 4-AP, using current density (J)-voltage (V) measurement method. The sensor also revealed excellent stability, reproducibility, and recoveries of DA, UA, and 4-AP in real samples.
关键词： dopamine,4-aminophenol,Graphene Oxide-Au nanocrystals,uric acid,electrochemical detection
更新于2025-09-23 15:22:29
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Atomic-thick TiO <sub/>2</sub> (B) nanosheets decorated with ultrafine Co <sub/>3</sub> O <sub/>4</sub> nanocrystals as a highly efficient catalyst for lithium-oxygen battery
摘要： Development of high efficient catalysts based on transition metal oxides (TMOs) is desirable, and remains a big challenge for lithium-oxygen (Li-O2) batteries. In the present work, atomic-thick TiO2(B) nanosheets decorated with ultrafine Co3O4 nanocrystals (Co3O4-TiO2(B)) was synthesized and utilized as cathode catalyst in Li-O2 batteries by designing a hybrid and inducing oxygen vacancies. The XPS characterization results suggested that the introduction of Co3O4 nanocrystals could induce numerous oxygen vacancies in the TiO2(B) nanosheets through Co doping in the hybrid catalyst. The subsequent electrochemical experiments indicated that the Li-O2 batteries with the prepared hybrid catalysts showed high specific capacity (11000 mAhg-1), and good cycling stability (200 cycles at a limited capacity of 1000mAhg-1) with low polarization (above 2.7V for discharge medium voltage and below 4.0V for charge medium voltage within 80 cycles). Furthermore, a possible working mechanism was proposed for a better understanding of the high performance of Co3O4-TiO2(B) catalysts for the Li-O2 batteries. This work also provided some new insights into designing efficient catalysts through interface engineering between 2D (two dimentional) TMOs and 0D (zero dimentional) TMOs for Li-O2 batteries or other catalysis related fields.
关键词： film-like Li2O2,oxygen vacancies,TiO2(B) nanosheets,Co3O4 nanocrystals,Li-O2 battery
更新于2025-09-23 15:21:21
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Achieving Near-Unity Photoluminescence Efficiency for Blue-violet Emitting Perovskite Nanocrystals
摘要： While the perovskite nanocrystals (NCs) have shown great promise as materials for efficient light emitting diodes (LEDs), low photoluminescence quantum yield (PLQY) of the blue-emitting perovskites is an impediment to the development of white LEDs of which blue is an essential component. Herein, we report that room temperature post-synthetic treatment of weakly blue-violet emitting (PLQY 3%) CsPbCl3 NCs with CdCl2 results in an instantaneous enhancement of the PLQY to near-unity without affecting the PL peak position (406 nm) and spectral width. The time-resolved PL and ultrafast transient absorption measurements confirm the removal of nonradiative defect states of the CsPbCl3 NCs in treated sample. The elemental composition and structural data of the treated sample reveal facile doping of Cd2+ into the crystal lattice without affecting the size and shape of the NCs. Extraordinary PLQY, high air- and photo-stability and ease of preparation of this Cd-doped CsPbCl3 make it by far the most attractive blue-emitting perovskite for development of efficient blue and white LEDs.
关键词： photoluminescence quantum yield,blue-emitting perovskites,perovskite nanocrystals,CdCl2 treatment,white LEDs
更新于2025-09-23 15:21:21