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Yb/Er/Tm tri-doped Na3ZrF7 upconversion nanocrystals for high performance temperature sensing
摘要： Non-contact optical thermometry based on fluorescence intensity ratio (FIR) technique has been widely researched over the past few decades. However, the reported systems exhibit two important shortcomings including the existence of a few interferential signals in addition to the required spectral bands for FIR and the absence of internal standard for reference signal. Herein, only two emission bands of Er3+: 4F9/2→4I15/2 (~673 nm) and Tm3+: 3H4 → 3H6 (~800 nm) are achieved in Yb/Er/Tm tri-doped Na3ZrF7 nano-system. Moreover, the upconversion (UC) emission intensity of Er3+ keeps unchanged with the rising of temperature, which is applied as reference signal; while that of Tm3+ enhances evidently, which is applied as temperature signal. The calculated maximum absolute temperature sensitivity (Sa) and relative temperature sensitivity (Sr) are 0.17 K-1 at 393 K and 1.76 %K-1 at 313 K, respectively.
关键词： Na3ZrF7 nanocrystals,self-reference,rare earth ions,temperature sensor,upconversion
更新于2025-11-14 17:04:02
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All-inorganic RbxCs1-xPbBrI2 perovskite nanocrystals with wavelength-tunable properties for red light-emitting
摘要： The outstanding photovoltaic performance of perovskite nanocrystals is attracting more and more attention. However, how to obtain stable wavelength-tunable red light-emitting perovskite materials is an urgent problem to be solved for the photovoltaic application. This paper reports a kind of orange to red light-emitting rubidium?cesium lead halide perovskite nanocrystals (RbxCs1-xPbBrI2, x = 0 to x = 0.6). By adjusting the rubidium?cesium ratios in the precursor solution, the peak wavelength can be tuned from 631 nm to 588 nm. The nanocrystals have narrow emission line-widths and bright photoluminescence. Furthermore, the polymer nanocrystals are prepared simply by mixing PMMA and perovskite nanocrystals solution in appropriate ratios, forming a series of stable orange to red emitting materials.
关键词： Nanocrystals,Rubidium,Stability,Photoluminescence,Perovskite
更新于2025-11-14 17:03:37
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Direct Hot-Injection Synthesis of Lead Halide Perovskite Nanocubes in Acrylic Monomers for Ultrastable and Bright Nanocrystal–Polymer Composite Films
摘要： In recent years, lead halide perovskite nanocrystals (NCs) have attracted significant attention in both fundamental research and commercial applications due to their excellent optical and optoelectrical properties. However, the protective ligands on the surface of the perovskites NCs could be easily removed after the tedious process of centrifugation, separation, and dispersion, which greatly hampers their stability against light, heat, moisture, and oxygen and limits their practical applications. Here we report a new post-processing-free strategy (i.e., without centrifugation, separation, and dispersion process) of using an UV-polymerizable acrylic monomer of lauryl methacrylate (LMA) as the solvent to synthesize CsPbBr3 NCs, and then adding polyester polyurethane acrylates oligomer, monomer (IBOA) and initiator for directly UV polymerization to fabricate NC-polymer composite films. These films exhibited an improved photoluminescence quantum yield (85-90%) than classic NC-film (40-50%), which were processed using octadecene (ODE) as the solvent for NC synthesis and post-processed for UV polymerization. Significantly, the as-fabricated films by post-processing-free strategy exhibited excellent photostability against strong Xe lamp illumination; while the other films using classic methods were quickly photo-degraded. Meanwhile, these NC-polymer composite films showed good stability against moisture and heating when aging in water at 50oC for over 200 hours. These films, along with K2SiF6:Mn4+ (KSF) phosphor emitters, were used as downconverters for blue LEDs in liquid crystal displays with a wide color gamut of 115% in the International Commission on Illumination (CIE) 1931 color space. This work provides a facile and effective strategy for the preparation of ultrastable and bright color-conversion NC films for the development of the next-generation wide color gamut displays.
关键词： display backlight,lead halide perovskite,colloidal nanocrystals,color-conversion optical films,photostability
更新于2025-11-14 17:03:37
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Highly efficient transparent nanophosphor films for tunable white light-emitting layered coatings
摘要： Bright luminescence in rare-earth (RE) nanocrystals, so-called nanophosphors, is generally achieved by choosing a host that enable the effective excitation of the RE activator through charge or energy transfer. Although tungstate, molybdate or vanadate compounds provide the aforementioned transfer, a comparative analysis of the efficiency of such emitters remains elusive. Herein we perform a combined structural and optical analysis, which reveals that the tetragonal GdVO4 matrix gives rise to the highest efficiency among the different transparent nanophosphor films compared. Then we demonstrate that by sequential stacking of optical quality layers made of Eu3+ and Dy3+ doped nanocrystals, it is possible to attain highly transparent white light emitting coatings of tunable shade with photoluminescence quantum yields above 35%. Layering provides precise dynamic tuning of the chromaticity based on the photoexcitation wavelength dependence of the emission of the nanophosphor ensemble without altering the chemical composition of the emitters or degrading their efficiency. Total extinction of incoming radiation along with the high quantum yields achieved make these thin layered phosphors one of the most efficient transparent white converter coatings ever developed.
关键词： rare-earth nanocrystals,transparent coatings,nanophosphors,phosphor materials,white-light emission
更新于2025-11-14 15:23:50
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Cesium lead halide perovskite nanocrystals for ultraviolet and blue light blocking
摘要： Direct exposure to ultraviolet (UV) light is closely related to various harmful effects [1-3], ranging from skin injures to cancer originated from DNA damage. Recent years, some studies reported that blue light are also detrimental to humans [4,5], for example, the blue light could cause photochemical lesions to human retinal within the intensity range of the natural light [6]. Furthermore, blue light is responsible for the solar retinitis and may play a role in age-related macular degeneration. Importantly, the harmful effects of blue lights generated from the electronic display devices should also be careful [7]. Thus, the development of new UV and blue light shielding materials has been received much attention [8]. In the past few years, there has been an increased awareness of the importance to develop UV shielding materials. A variety of materials have been used to prevent UV lesions. Organic molecules like avobenzone or oxybenzone have been used as a UV absorber for many years, but the self-degradation limits their usage time. Inorganic materials such as zinc oxide (ZnO) and titanium oxide (TiO2) have been used intensively for UV shielding [9-12]. However, photocatalytic properties and self-degradations of the ZnO and TiO2 based absorbers also hindered their applications [13,14]. Other materials, e.g., graphene oxide-poly(vinyl alcohol) composite film and lanthanide complex functionalized cellulose nanopaper were also reported for UV shielding [15,16]. Whereas, the excellent UV-filtering capability of these films was obtained by sacrificing the visible light transmittance. Therefore, fabricating UV and blue light blocking materials with good photostability and high transparency to the rest of visible light still remains a challenge and is urgently needed to be developed. Recently, because of the outstanding performance in photovoltaic applications, lead halide perovskite APbX3 (where A = CH3NH3+, (NH2)2CH+ and Cs+, X = Cl?, Br? and I?) has become the most noticeable materials [17-22]. These perovskite nanocrystals exhibit intriguing features [23], such as easy tunable band gap, sharp optical absorption edges and high quantum efficiency with narrow emission spectra. These nanocrystals have been studied extensively for various optical applications, especially light emitting diodes and lasers [24-27]. Post modification of perovskite nanocrystals by anion exchange enables the absorbance band gap tuned from ultraviolet to near infrared spectra [28,29]. In addition, the perovskite nanocrystals show large absorption range, which offers the great potential for UV and blue light shielding applications. Although the tunable absorption-band edge of perovskite nanocrystals has already been realized, there have not been reports on developing UV and blue light blocking material with tunable absorption-band edge. Herein, we aim to the development of a simple and easy way to fabricate UV and blue light blocking material by mixing pervoskite nanocrystals and ethyl cellulose (EC). In this study, EC was used as a host material for the CsPb(Cl/Br)3 pervoskite nanocrystals. By tuning the ratio of Br to Cl, the blocked wavelength range could be easily controlled. Using the sharp absorption edges, the material possesses excellent light blocking ability in the range of 200-460 nm and maintains high transparency (95%) to visible light in the range beyond blue light.
关键词： UV blocking,Cesium lead halide nanocrystals,Blue light blocking,Tunable adsorption edge,Perovskite nanocrystals
更新于2025-09-23 15:23:52
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Stark Effect and Environment-Induced Modulation of Emission in Single Halide Perovskite Nanocrystals
摘要： Organic-inorganic halide perovskites have emerged as promising materials for next generation solar cells. In nanostructured form also, these materials are excellent candidates for optoelectronic applications such as lasers and light emitting diodes for displays and lighting. While great progress has been achieved so far in optimizing the intrinsic photophysical properties of perovskite nanocrystals (NCs), in working opto-electronic devices external factors, such as the effects of conducting environment and of the applied electric field on exciton generation and photon emission have been largely unexplored. Here, we use NCs of the all-inorganic perovskite CsPbBr3 dispersed polyvinyl carbazole, a hole-conductor, and in polymethyl methacrylate, an insulator, to examine the effects of applied electric field and conductivity of the matrix on the perovskite photophysics at single-particle level. We found that the conducting environment causes a significant decrease of photoluminescence (PL) brightness of individual NCs due the appearance of intermediate-intensity emitting states with significantly shortened lifetime. Applied electric field has a similar effect and, in addition, causes a non-linear spectral-shift of the PL maxima, a combination of linear and quadratic Stark effect caused by environment-induced polarity and field-related polarizability. The environment and electric field effects are explained by ionization of the NCs through hole transfer and emission of the resulting negatively-charged excitons.
关键词： ionization,halide perovskite nanocrystals,single-particle spectroscopy,Stark effect,blinking
更新于2025-09-23 15:23:52
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Study on the preparation of CdTe nanocrystals on the surface of mesoporous silica and evaluation as modifier of carbon paste electrodes
摘要： Here CdTe nanocrystals were grown onto mesoporous silicas. The influence of the surface areas, volumes and pore diameters of the silica matrices on the spectroscopic properties of CdTe was evaluated. Emission properties of the CdTe were found to depend on the textural properties of silicas. Electrochemical characterization of different electrodes (unmodified carbon paste, and carbon paste modified with the mesoporous silica and with CdTe anchored onto mesoporous silica) evidenced that the presence of CdTe nanocrystals lead to a significant increase of the anodic peak referring to Cu2+ detection. The electrode with optimal characteristics responded to Cu2+ in the linear range from 5.0 × 10?8 to 2.3 × 10?6 mol L?1 and the calculated limit of detection was 6.4 × 10?8 mol L?1. The method developed here proved to be efficient for monitoring Cu2+ in sugar cane spirit (cacha?a), with quantitative results comparable to those obtained from Flame Atomic Absorbtion Spectroscopy.
关键词： CdTe nanocrystals,Mesoporous silicas,Electrochemical sensors
更新于2025-09-23 15:23:52
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Water-soluble titanium-oxides: Complexes, clusters and nanocrystals
摘要： The water-soluble titanium-oxide structures covered in this review span a continuum from molecular clusters to colloidal nanocrystals. Here, a deliberate distinction is made between titanium clusters and nanoparticles with organic ligands, soluble in organic solvents, and related structures prepared and soluble in water. This distinction is made in response to rapid developments in three areas covered in this article: small titanium-oxide clusters prepared at low pH values in water, heterpolytungstate macroanions with high-nuclearity titanium-oxide cores, and polyoxometalate complexes of anatase-phase TiO2. The latter nanostructures occupy a unique position between polyoxometalate macroanions and traditional colloidal TiO2. As such, the progressively larger water-soluble titanium-oxide structures covered in the three main sections of this review establish a continuum that begins to blur the longstanding divide between molecular and colloid science.
关键词： Polyoxometalates,Titanium oxide,Water soluble,Clusters,Nanocrystals
更新于2025-09-23 15:23:52
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Coating of 2D Flexible Metal–Organic Frameworks on Metal Nanocrystals
摘要： We report, for the first time, metal (Pd) nanocrystals (NCs) covered with a 2D flexible metal–organic framework (MOF) of [Zn(NO2-ip)(bpy)]n (NO2-ip: 5-nitro-isophthalate, bpy: 4,4′-bipyridine). The hybrid materials were characterized by powder X-ray diffraction measurements and transmission electron microscope techniques. The CO2 sorption and hydrogen storage properties revealed that both the flexible porous character of the MOF and the hydrogen absorption ability of Pd NCs were compatible in the hybrid.
关键词： Gate-opening behavior,Metal–organic frameworks,Metal nanocrystals
更新于2025-09-23 15:23:52
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Absence of free carriers in silicon nanocrystals grown from phosphorus- and boron-doped silicon-rich oxide and oxynitride
摘要： Phosphorus- and boron-doped silicon nanocrystals (Si NCs) embedded in silicon oxide matrix can be fabricated by plasma-enhanced chemical vapour deposition (PECVD). Conventionally, SiH4 and N2O are used as precursor gasses, which inevitably leads to the incorporation of ≈10 atom % nitrogen, rendering the matrix a silicon oxynitride. Alternatively, SiH4 and O2 can be used, which allows for completely N-free silicon oxide. In this work, we investigate the properties of B- and P-incorporating Si NCs embedded in pure silicon oxide compared to silicon oxynitride by atom probe tomography (APT), low-temperature photoluminescence (PL), transient transmission (TT), and current–voltage (I–V) measurements. The results clearly show that no free carriers, neither from P- nor from B-doping, exist in the Si NCs, although in some configurations charge carriers can be generated by electric field ionization. The absence of free carriers in Si NCs ≤5 nm in diameter despite the presence of P- or B-atoms has severe implications for future applications of conventional impurity doping of Si in sub-10 nm technology nodes.
关键词： photoluminescence,silicon nanocrystals,transient transmission,doping,atom probe tomography
更新于2025-09-23 15:23:52