Luminescent Patterns Research Articles

Remarkable laser-driven upconverting photothermal effect of Cs3LnF6@glass nanocomposites for anti-counterfeiting

Currently, advanced security strategies have aroused widely interest in anti-counterfeiting field to ensure the authentic items difficult to be replicated. Herein, cubic Cs3LnF6 (Ln = Y, Yb, Lu, Sc) nanocrystals embedded glasses are successfully prepared via an in-situ glass crystallization strategy. Emitting centers, such as Eu3+, Er3+, Ho3+ and Tm3+, can be incorporated into the precipitated Cs3YF6, Cs3YbF6 and Cs3LuF6 crystal lattices but remain in glass matrix rather than in Cs3ScF6 crystals for large ionic radius mismatch between lanthanide activators and Sc3+ host ions. It is demonstrated that upconverting quantum yields of all the Yb/Er: Cs3LnF6@glass samples are higher than those of well-known cubic/hexagonal Yb/Er: α/β-NaYF4@glass samples. Specifically, Yb/Er: Cs3LuF6@glass exhibits a maximal quantum yield of ~0.30%, which is superior to Yb/Er: β-NaYF4 @glass (~0.19%). Impressively, Er: Cs3YbF6@glass shows a remarkable 980 nm laser-induced photothermal effect, leading to significant alteration of upconversion emissive color from red to green with increase of incident laser power. As a prototype of the concept for practical application, a series of luminescent patterns using Er: Cs3YbF6@glass upconverting inks are constructed by a screen-printing technique and show distinct laser-power-sensitive emissive colors, being feasible for high-level anti-counterfeiting. The present work exploits a new anti-counterfeiting strategy by developing highly efficient laser-induced upconverting photothermal materials.

Making Graphene Luminescent by Direct Laser Writing

Graphene is not intrinsically luminescent, due to a lack of bandgap, and methods for its creation are tricky for device fabrication. In this study, we create luminescent graphene patterns by a simp...

In Vivo Shaping of Inorganic Functional Devices using Microalgae.

The usage of biomineralization processes performed by living microalgae to create 3D nanostructured materials are advantageous compared to conventional synthesis routes. Exploitation of in vivo shaping using living cells leads to inorganic intricate biominerals, produced with low environmental impact. Since biomineralization processes are genetically controlled, the formation of nanostructured materials is highly reproducible. The shells of microalgae, like coccoliths, are particularly of great interest. This study shows the generation of mesoporous highly structured functional materials with induced optoelectronical properties using in vivo processes of the microalga species Emiliania huxleyi. It demonstrates the metabolically driven incorporation of the lanthanide terbium into the coccoliths of E. huxleyi as a route for the synthesis of finely patterned photoluminescent particles by feeding the microalgae with this luminescent element. The resulting green luminescent particles have hierarchical ordered pores on the nano- and microscale and may act as powerful tools for many applications; they may serve as imaging probes for biomedical applications, or in microoptics. The luminescent coccoliths combine a unique hierarchical structure with a characteristic luminescence pattern, which make them superior to conventional produced Tb doted material. With this study, the possibility of the further exploitation of coccoliths as advanced functional materials for nanotechnological applications is given.

Tuning the luminescence spectra and spatial patterns of NaYF4 upconversion microrod arrays via morphology and Yb3+ concentration control

Lanthanide doped β-NaYF4 micro/nanocrystals have attracted extensive attentions for various applications by taking advantage of their ability to convert near-infrared into high-energy visible or ultraviolet emission. However, to date, achieving efficient photon upconversion (UC) and distinct far-field luminescent patterns of emission light in UC phosphors is still a fundamental challenge. Here, we report the utilization of the microrod cavity waveguide arrays with the concave top/bottom surfaces to manipulate energy flux and significantly enhance UC processes. By enhancing incident light harvesting and changing Yb3+ concentration, directional luminescence amplification and chrysanthemum-shaped luminescent pattern with various colors can be achieved relative to its disorderly microrod counterpart stackings. This design delineates a strategy of energy flux manipulation to converge a low-power incident light beam into a photonic hotspot of high field intensity and amplify the UC processes resulting in directional luminescence and stereoscopic luminescent patterns.

Highly luminescent and ultrastable cesium lead bromide perovskite patterns generated in phosphate glass matrices.

Owing to their exceptional optoelectronic properties, all-inorganic lead halide perovskites offer enormous potential for next generation photonic, light-emitting, and optoelectronic devices. However, their usage is significantly limited by their poor stability upon moisture exposure and lead toxicity issues. Moreover, many of the aforementioned applications rely on the development of confined perovskite patterns of various shapes and periodicities. Here we report a simple and low-temperature method enabling the controlled incorporation of photoluminescent all-inorganic metal halide PNCs into a silver phosphate glass (AgPO3) matrix which is transparent in most of the visible range. The developed fabrication protocol is based on a simple melting encapsulation process in which pre-synthesized perovskite crystals are inserted in the glass matrix, following the initial glass quenching. Using this novel approach, two types of composite perovskite glasses are prepared, one that hosts perovskite isles and the second in which a thin perovskite layer is embedded beneath the glass surface. Both types of composite glasses exhibit remarkable photoluminescence stability when compared to the ambient air-exposed perovskite crystals. More importantly, by means of a simple and fast cw-laser processing technique, we demonstrate the development of encapsulated dotted perovskite micropatterns within the composite perovskite glass. The ability of the proposed system to resolve stability and lead toxicity issues, coupled with the facile formation of highly luminescent perovskite patterns pave the way towards the broad exploitation of perovskite crystals in photonic applications.

In situ localized formation of cesium lead bromide nanocomposites for fluorescence micro-patterning technology achieved by organic solvent polymerization

A femtosecond laser processing strategy was proposed to fabricate luminescent patterns composed of in situ crystallized cesium lead bromide nanocomposites.

Self-suspended rare-earth doped up-conversion luminescent waveguide: propagating and directional radiation

Near-infrared excited rare-earth (RE)-doped up-conversion (UC)-luminescent materials have attracted enormous attention because of their unique emission properties, such as narrow emission bands, long luminescence lifetimes, and multiple colors. However, current development of RE-doped luminescent material is hindered by weak and narrowband absorption problems and low photon-conversion quantum efficiencies. In addition to conventional approaches to enhance fluorescence intensity, controlling emission directivity to improve detection efficiency has become a promising approach to obtain higher luminescence brightnesses. In this paper, a self-suspended RE-doped UC luminescent waveguide is designed to realize directional emissions. Benefitting from the special morphology of the crown-like NaYF4:Yb3+/Er3+ microparticle, the points contact between the waveguide and substrate can be obtained to decrease energy loss. An attractive UC luminescent pattern accompanied by powerful and controllable directional emissions is observed, and the spatial emission angle and intensity distribution are explored and analyzed in detail by introducing Fourier imaging detection and simulation. This work provides a new method for achieving controllable directional fluorescence emissions and obtaining improved detection efficiency by narrowing emission directivity, which has potential applications in 3-dimensional displays and micro-optoelectronic devices, especially when fabricating self-fluorescence micron lasers.

Fe3+ detection, bioimaging, and patterning based on bright blue-fluorescent N-doped carbon dots.

Bright blue fluorescent N-doped carbon dots (N-CDs) with satisfactory yield (54%) were successfully fabricated by one-step hydrothermal treatment of astragalus. The obtained N-CDs possessed superior stability, solubility and high resistance to photo bleaching, and can be used as label-free nanosensors for the determination of Fe3+. The quantitative analysis of Fe3+ showed a linear range of 50 to 250 μM with the detection limit as low as 42 nM. Moreover, the as-prepared N-CDs have been used in cellular imaging owing to their distinct merits of simplicity, convenience, fast response and good selectivity towards Fe3+. Besides, the N-CDs could also be further used as fluorescent inks for drawing luminescent patterns.

In situ fabrication of a luminescent copper nanocluster/eggshell membrane composite and its application in visual detection of Ag+ ions, light-emitting diodes and surface patterning.

In this work, we report a novel strategy for fabricating a luminescent 2D nanocomposite at room temperature by in situ generation of luminescent copper nanoclusters (Cu NCs) embedded in natural monolithic eggshell membrane (ESM) using dithiothreitol as the reducing and capping agent. The established fabrication is facile, cost-effective and viable. The as-prepared Cu NC/ESM nanocomposite exhibited excellent photoluminescence performance, improved chemical, thermal and photo stability, convenient tailoring and flexibility. Significantly, the nanocomposites could be employed as test strips for the visual detection of Ag+ ions based on the luminescence quenching phenomenon and as color conversion layers in light-emitting diodes. Furthermore, application of the proposed strategy for surface luminescence patterning was well demonstrated, indicating great potential in biomass based anti-counterfeiting, information encryption and security paper or sheets.

A broad overview on innovative functionalized paper solutions

Abstract Functionalized paper solutions have attracted the attention of many research groups in the 21st century, given the low cost, availability, flexibility and biodegradability of paper. Despite this material has been manufactured for more than two thousand years, its traditional uses hardly go beyond writing, printing, cleaning and packaging. This overview covers fascinating advances in the functionalization of paper that have taken place this century. This century, test strips for glucose and pH have evolved towards microfluidic paper analytical devices that allow for accurate quantitative determinations. In another context, paper electronics started with the first paper-based transistors and followed with more sophisticated electronic devices. Also, cheap paper-based membranes and adsorbents have been proposed for water treatment, and researchers have found innovative ways to confer antimicrobial and anti-counterfeiting properties to paper. Furthermore, numberless ways to functionalize paper are reported here. Fibers can be modified by chemical reactions, nanofibrillation or supramolecular interactions with certain reagents. The surface can be coated by diverse methods, including size press coating, sputtering, e-beam evaporation and the sol-gel process. Special inks can be printed onto paper to make hydrophobic, conductive or luminescent patterns. Brief opinions about future outlooks are given at the end.

Reversible Redox Switching of Concurrent Luminescence and Visual Color Change Based on Lanthanide Metallogel.

The development of reversible redox supramolecular gels capable of concurrent luminescence switch and visible color change with the facile redox process has always been an intriguing challenge. A redox-responsive supramolecular lanthanide metallogel with strong luminescence and yellow color is obtained via coordination interaction between 3,5-dinitrosalicylic acid (DNSA) and europium (Eu3+). Upon the addition of TiO2 to the prepared gel (DNSA/Eu3+ gel), the oxidation process of the gel (DNSA/Eu3+/TiO2 gel) can be easily achieved by UV irradiation. The DNSA/Eu3+/TiO2 gel exhibits a concurrent reversible "on-off" luminescence and color change in response to redox stimuli. The DNSA/Eu3+/TiO2 gel shows a concurrent quench of luminescence and a color change from yellow to red when the gel was stimulated by the reductant. Upon UV irradiation, the luminescence and color of the reduced DNSA/Eu3+/TiO2 gel restored to its initial state due to the strong oxidation ability of hydroxyl radicals derived from photocatalytic oxidation of TiO2. The results of UV-vis and mass spectroscopy indicated that the reversible redox responsiveness of DNSA/Eu3+/TiO2 gel depends on the reversible oxidation-reduction reactions of DNSA. Moreover, DNSA/Eu3+/TiO2 gel remains stable because the morphology of the gel had no change during the redox process. Exemplarily, the application of DNSA/Eu3+/TiO2 gels to achieve luminescent patterning was investigated. The results demonstrated that the prepared metallogel has potential applications in the fields of writable materials, anticounterfeiting, sensors, and others.

2136. Rapid Antimicrobial Susceptibility Testing using ATP Luminescence and Machine Learning Methods

BackgroundTo prevent the spread of drug-resistant bacteria, a rapid and accurate antimicrobial susceptibility test (AST) is necessary. Recently, morphokinetic microscopy approaches have been reported as a rapid AST method. However, these still require several hours to obtain a minimum inhibitory concentration (MIC). Adenosine triphosphate (ATP) luminescence has also been reported as a rapid AST method that can detect bacterial growth more rapidly than morphokinetic approaches, since ATP in bacteria increases prior to bacterial division. In this study, we designed a new machine learning-based algorithm that predicts MIC rapidly, using a dataset that contains ATP luminescence patterns and conventional MICs determined by turbidity. Essential agreement (EA) rates between rapid and conventional MIC were then evaluated.MethodsSixty-three strains of E. coli (ATCC 25922 and clinical isolates from Toyama University Hospital) were tested. Bacterial suspensions were diluted 500-fold in Mueller–Hinton broth from 0.5 McF solutions, and the final concentration of bacteria was 3×105 CFU/mL. The suspensions were dispensed into a 96-well microplate, which had 12 antimicrobials in two-fold dilution series, and the microplate was incubated at 35°C. At each measurement time point, the amount of ATP in a 10 μL aliquot from each well was evaluated by our original measurement system, which can sensitively detect ATP luminescence equivalent to a single bacterium. After 22 hours, MIC was determined conventionally by measuring turbidity. A rapid MIC for each bacterium was estimated by the algorithm based on the dataset consisting of the rest of the 62 strains (leave-one-out cross validation).ResultsTable 1 shows the EA rate for the 12 antimicrobials; EA rates > 90% were achieved for 7 antimicrobials in 2 hours and for 12 antimicrobials in 3 hours. In 6 hours, an average EA rate > 97% was achieved.ConclusionUsing the dataset, our new machine learning-based algorithm predicted MIC rapidly within 2 hours with an EA rate > 90% for 7 antimicrobials. The rapid AST detected by the ATP luminescence method will contribute toward both appropriate antimicrobial treatment and reduction in medication and admission charges. In the future, other species of bacteria will be evaluated by our ATP method. Disclosures All authors: No reported disclosures.

Design of core/active-shell NaYF4:Ln3+@NaYF4:Yb3+ nanophosphors with enhanced red-green-blue upconversion luminescence for anti-counterfeiting printing

Lanthanide-doped NaYF4 upconversion luminescent nanophosphors have attracted great interest for anti-counterfeiting applications. However, low luminescent intensity caused by surface defects and low extinction coefficients of lanthanide dopants greatly limits their practical applications. Herein, we developed core/active-shell NaYF4:Ln3+@NaYF4:Yb3+ (e.g. NaYF4:Er3+/Tm3+@NaYF4:Yb3+, NaYF4:Yb3+/Er3+@NaYF4:Yb3+, and NaYF4: Yb3+/Tm3+@NaYF4:Yb3+) nanophosphors with enhanced near-infrared (NIR)-to-visible upconversion luminescence by coating Yb3+-doped NaYF4 shell (active-shell) on NaYF4:Ln3+ upconversion core nanoparticles. The structure, morphology, and elemental composition of NaYF4:Ln3+@NaYF4:Yb3+ core/active-shell nanoparticles (CASNs), NaYF4:Ln3+@NaYF4 core/inert-shell nanoparticles, and NaYF4:Ln3+ core nanoparticles were characterized and compared systematically to reveal their structure-property relationship. Collective data showed that coating of a NaYF4:Yb3+ active shell on NaYF4:Ln3+ cores significantly enhanced upconversion luminescent intensity by ~21 times, while an inert (pure NaYF4) shell coated on the surface of NaYF4:Ln3+ core only resulted in 5.2 times luminescence enhancement. The enhanced upconversion luminescence intensity was mainly attributed to (i) the NaYF4 shell-reduced quenching effect and (ii) the promoted transformation of the absorbed NIR light from the pump source to the core nanoparticles by Yb3+ sensitizer in the active shell. Moreover, by tailoring dopant pairs and molar ratios of lanthanide ions in the core nanoparticles, three CASNs with enhanced red, green, and blue upconversion luminescence were obtained and fabricated into environmental benign luminescent inks. The inkjet printing of RGB CASNs inks on papers produced multiple-color, high-resolution, complex luminescent patterns under 980 nm laser. This work expands the lanthanide-doped NaYF4 materials for anti-counterfeiting applications.

Direct observation of multimode interference in rare-earth doped micro/nanofibers.

Modal inspection of optical fibers is important for multimode application but it is challenging to collect in-situ information of propagating modes for evaluation and manipulation. Here we demonstrate direct observation of multimode interference in Er3+/Yb3+ co-doped micro/nanofibers. Luminescent interference patterns are visualized by visible up-conversion of Er3+ ions and are used for establishing the existence of higher order modes co-propagating with fundamental modes. We use fast Fourier transform to analyze the patterns in detail and obtain excellent agreement between experiment and calculation on beat lengths of the interference. Effective index differences among higher order modes and a fundamental mode of a microfiber are also experimentally investigated with the assistance of interference patterns, revealing the characteristic of modal dispersions.

Rapid and Eco-Friendly Synthesis of Red Fluorescent Gold Nanoclusters for Sensing and Anti-Counterfeiting Applications

A rapid and eco-friendly synthesis method for the preparation of gold nanoclusters (Au NCs) with strong red emission has been developed. A one-pot microwave (MW) irradiation method yields bright red-emitting Au NCs, providing an easy route for the synthesis of fluorescent Au NCs without the need for a tedious operation, time-consuming procedure, or the use of toxic/corrosive agents and harsh conditions. The as-prepared Au NCs show a small-sized distribution, good dispersibility and a broad excitation band (from UV light to visible light). The optimal experimental conditions, including concentrations and order of addition of Na2CO3, bovine serum albumin (BSA), and HAuCl4and the time of MW irradiation, were investigated in detail. The as-synthesized Au NCs were well characterized by fluorescence spectroscopy, UV-Vis spectroscopy, infrared spectroscopy, high-resolution transmission electron microscopy-energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. Due to favorable photoluminescence features as well as minimal toxicity, the Au NCs could be applied to sensing, patterning and anti-counterfeiting. The Au NCs displayed strong red emission that was efficiently quenched by hydrogen peroxide (H2O[Formula: see text]. More strikingly, the obtained Au NCs were used as a fluorescent ink for producing luminescent handwriting and patterns, which may expand the potential applications of Au NCs in the fabrication of security inks.

Luminescent and DFT Study of Keto-Enol Tautomers of 5-Fluorouracil and Its Derivatives in Aqueous Solutions.

Fluorescence (FL) spectra were recorded and identified for the following 5-fluorouracil (FU) tautomers: 5-fluoropyrimidine-2,4(1H,3H)-dione (A), 5-fluoro-2-hydroxypyrimidine-4(3H)-one (B), and 5-fluoro-4-hydroxypyrimidine-2(1H)-one (D), as well as the corresponding tautomers A and D of 1-(tetrahydrofuranyl-2)-5-fluorouracil and 1-methyl-5-fluorouracil, tautomers A and B of 3-methyl-5-fluorouracil, and the diketo tautomer of 1,3-dimethyl-5-fluorouracil. It was shown that the FL of rare tautomers of FU derivatives occurs by the excitation of uracil homoassociates followed by intramolecular proton transfer (IPT), formation of a pair of rare tautomers, and radiative deactivation of one of them. The FL quantum yields φi were estimated. In the case of rare tautomers, the φi value includes the probability of IPT in the homoassociate, and density functional theory calculations in the TPSSTPSS/6-311+G(d,p) approximation were used to determine the relative energies of tautomers, associated FU forms, and their spectral properties that agree with the observed luminescence pattern.

Nanoscale mapping of quasiparticle band alignment

Control of atomic-scale interfaces between materials with distinct electronic structures is crucial for the design and fabrication of most electronic devices. In the case of two-dimensional materials, disparate electronic structures can be realized even within a single uniform sheet, merely by locally applying different vertical gate voltages. Here, we utilize the inherently nano-structured single layer and bilayer graphene on silicon carbide to investigate lateral electronic structure variations in an adjacent single layer of tungsten disulfide (WS2). The electronic band alignments are mapped in energy and momentum space using angle-resolved photoemission with a spatial resolution on the order of 500 nm (nanoARPES). We find that the WS2 band offsets track the work function of the underlying single layer and bilayer graphene, and we relate such changes to observed lateral patterns of exciton and trion luminescence from WS2.

Controllable planar electrodeposition of NaYF4: Yb3+, Er3+ thin films with efficient upconverting fluorescence

The lanthanide doped NaYF4, one of the most efficient upconverting materials, which shows great potential in the applications of future optoelectronic devices. Although there are many progress on the synthesis and performance modulations of upconversion fluorescence single crystal and nanoparticles, it is still a great challenge to fabricate upconverting thin film to compatible with modern planar silicon photoelectronic devices. In this work, patterned NaYF4: Yb3+, Er3+ thin films were prepared by a well-designed strategy combined with photolithography and electrodeposition at 50 °C. The thickness of NaYF4: Yb3+, Er3+ thin films could be modulated from 1.6 ± 0.3 to 6.1 ± 0.4 μm by the deposition time. After the further annealing at 300 °C, the NaYF4: Yb3+, Er3+ thin films present efficient green upconversion fluorescence with fine spectra from 510 to 720 nm, which resulted from the electronic transitions of doped Er3+ ions. The application of laser direct-writing mask could introduce the desired micropattern of NaYF4: Yb3+, Er3+ thin films, which show uniform distributed green upconversion fluorescence pixel with fine resolution of about 50 μm. The intense upconversion luminescence pattern with high spatial resolution show great application potential in the fields of displays, photodetectors, biological sensors, solar energy converter and commercial anticounterfeiting.

Förster Resonance Energy Transfer Regulated Multicolor Photopatterning from Single Quantum Dot Nanohybrid Films

Precise patterning and localization of functional nanomaterials is the key step for miniaturization and building of optoelectronic devices. Present study utilizes a robust methodology for the multicolor patterning of luminescent Indium Phosphide/Zinc Sulfide Quantum Dot (InP/ZnS QD) film, by taking the advantage of QD’s enhanced photostability over organic dyes. The photoirradiation regulates the composition of donor–acceptor pair, and thereby, the efficiency of Förster Resonance Energy Transfer (EFRET) in QD–dye nanohybrid film. The photopatterned films are reusable over multiple cycles without any compromise of the color clarity, owing to the reversible switching between FRET ON and OFF states. The highlight of the present work is the use of a single QD nanohybrid system to create multicolor luminescent patterns; as opposed to the common practice of using different-colored QDs. FRET assisted photopatterning of luminescent InP/ZnS QD films provides a fundamentally unique and cost-effective approach for the manufacturing of luminescent optoelectronic devices.

Multilevel Static–Dynamic Anticounterfeiting Based on Stimuli-Responsive Luminescence in a Niobate Structure

Anticounterfeiting is a highly required technique to protect the product and the consumer rights in the modern society. The conventional luminescent anticounterfeiting is based on downconversion luminescence excited by an ultraviolet light, which is easy to be faked. In this work, we realized six luminescent modes in a niobate-based structure (LiNbO3:RE3+, RE3+ = Pr3+, Tm3+, Er3+, Yb3+), in which photostimulated luminescence of LiNbO3:Pr3+, and upconversion luminescence color evolution of LiNbO3:Er3+ were first presented. Based on the above luminescent modes of LiNbO3:RE3+, multilevel anticounterfeiting devices were developed. By employing mechanoluminescence and persistent luminescence, we achieved dual-mode anticounterfeiting that could display the luminescent patterns without any direct irradiation. In addition, another dual-mode anticounterfeiting based on photostimulated luminescence and upconversion luminescence excited by a near-infrared light was realized, which could display the anticounterfeiting patterns in both static and dynamic states. To obtain an even higher anticounterfeiting level, downconversion luminescence, thermoluminescence, photostimulated luminescence, and upconversion luminescence were simultaneously applied in a food trademark. This four-mode anticounterfeiting trademark could not only show a static-dynamic luminescence that is hard to be faked but also allow consumers to distinguish the food freshness. The presented multilevel anticounterfeiting strategies could be employed to resolve the counterfeit issues in various fields.