Bright Yellow Emission Research Articles

The Phase Transition and Photoluminescence Properties of (Ca9−x Sr x )Mg1.5(PO4)7:Eu2+ Solid-Solution Phosphors

A series of color-tunable (Ca9−x Sr x )Mg1.5(PO4)7:Eu2+ (0 ≤ x ≤ 9) phosphors are designed by using mineral-inspired structural design strategy and synthesized by solid-state reaction. The mineral structure β-Ca3(PO4)2-type compounds, Ca9Mg1.5(PO4)7 and Sr9Mg1.5(PO4)7 are chosen as structural prototypes. Both of them are hexagonal structure but have different space groups. The former has R3c space group, while the latter possesses R3m space group. When Ca9Mg1.5(PO4)7 compound is used as maternal materials, the powder X-ray diffraction results demonstrate that the successive substitution of Ca2+ with Sr2+ ions expands and distorts the lattice parameters and unit cell volume of Ca9Mg1.5(PO4)7 compound, rendering phase transition from the (Ca9−x Sr x )Mg1.5(PO4)7:Eu2+ (phase 1, 0 ≤ x < 3) with R3c space group to (Ca9−x Sr x )Mg1.5(PO4)7:Eu2+ (phase 2, 5 < x ≤ 9) with R3m space group. The phase transition causes noticeable spectral redshift from the original blue-violet emission of x = 0 to bright yellow emission of x = 9 sample. Importantly, at x = 1, a bright white-light emission with a full width at half maximum of ∼255 nm is discovered in Ca8SrMg1.5(PO4)7:Eu2+ phosphor, which is beneficial to achieve phosphor-converted white-light-emitting diodes with high color-rendering index. These findings indicate that the mineral-inspired structural design strategy is very helpful for the development of new phosphors.

Hydrothermal synthesis and luminescence properties of Dy3+ doped SrMoO4 nano-phosphor

Dysprosium (Dy3+) doped SrMoO4 nanophosphors were synthesized by hydrothermal method. The characterization of synthesized samples was done by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), High Resolution Transmission Electron Microscope (HR-TEM), Energy Dispersive Spectra (EDS), Ultraviolet–Visible microscope (UV), Fourier Transform Infrared (FT-IR) techniques and Photoluminescence (PL). The results reveal that the constituted SrMoO4 phosphor has a single phase scheelite structure with tetragonal symmetry and crystalline size is in the range of 10–50 nm. The formation of crystalline Nano rod nature of the sample has been confirmed by the TEM. Photoluminescence spectra show blue emission at 485 nm and bright yellow emission at 576 nm monitored at 353 nm excitation. The optimum concentration of Dy3+ doped SrMoO4 was found to be 6 mol %.

1-Oxo-1H-phenalene-2,3-dicarbonitrile Based Sensor for Selective Detection of Cyanide ions in Industrial Waste

A phenalenedicarbonitrile (1-oxo-1H-phenalene-2,3-dicarbonitrile) based probe 3 has been synthesized by following oxidative nucleophilic substitution of aromatic hydrogen reaction (SNArH) also called green reaction. Probe 3 is found to be selective towards detection of cyanide (CN−) ions even in the presence of other anions. It originally gives pink color in H2O-CH3CN (1:9, v/v) and is found to be non-emissive when observed under Ultraviolet (UV) lamp. Upon adding of CN− ions to solution of probe 3 (20 µM, H2O-CH3CN (1:9, v/v)) the pink color of probe 3 is bleached out and bright yellow emission is attained when observed under UV-lamp. The colorimetric changes are also accompanied by spectral changes. The absorption and low-intensity emission maximum of probe 3 have been observed at 527 nm and 567 nm, respectively but upon adding CN−, the absorption at 527 nm is quenched with formation of new band at 454 nm whereas enhancement in emission band at 567 nm is observed. Probe 3 shows strong binding for CN− ions and binding constant is calculated to be 1.1 × 104 M−1 through fluorescence titration profile and can detect CN− as low as 5.5 × 10−8 M. Binding mechanism of CN− with probe 3 is analyzed through infra-red spectroscopy and proton NMR titration, which reveals that CN− ions attack chemodosimetrically on -C=O of probe 3 to form cyanohydrin. Probe 3 is also used for detection of CN− in industrial waste water. The spectral changes of probe 3 in presence of a specific ion have been used to design a 1-to-2 decoder.

Investigation of Gd2O3: Er3+/Yb3+ Upconversion Nanoparticles (UCNPs) as a Multi-model Contrast Agent for Functional Optical Coherence Tomography (fOCT).

Currently, upconversion nanoparticles (UCNPs) implanted as a contrast agent for optical coherence tomography (OCT) system due to its biocompatibility, anti-stock emission, narrow emission bandwidth non-photobleaching effects etc., but it was not used as multi model imaging probe. We synthesized multimodal imaging probe having upconversion property along with paramagnetic property and used as dual contrast agents for Photothermal Optical Coherence Tomography (PTOCT) and Magnetomotive Optical Coherence Tomography (MMOCT). The synthesized Gd2O3:Er3+/Yb3+ UCNPs shows the bright yellow upconversion emission, biocompatibility with hydrophilic property. A custom built SSOCT setup modified for PTOCT and MMOCT imaging along with custom MATLAB algorithm for signal extraction. A dynamic study was performed with synthesized UCNPs as an imaging probe and functional OCT system for targeted imaging. This shows the utility of the Gd2O3:Er3+/Yb3+ UCNPs as molecular probe for targeted imaging applications.

Yellow emission carbon dots for highly selective and sensitive OFF-ON sensing of ferric and pyrophosphate ions in living cells

A simple “OFF-ON” fluorescent system was proposed for selective and sensitive detection of ferric ion (Fe3+) and pyrophosphate (PPi) in living cells. The method was constructed based on the bright yellow emission of carbon dots (y-CDs), which were prepared using o-phenylenediamine (OPD) as the precursor via a facile hydrothermal treatment. The as-obtained y-CDs, with an average size of 2.6 nm, exhibited an excitation-independent emission peak at 574 nm. The fluorescence of y-CDs can be remarkably quenched by Fe3+ with high selectivity and sensitivity. Interestingly, the quenched fluorescence can be recovered regularly upon addition of PPi, showing a promising detection for PPi. The linear ranges for Fe3+ and PPi detections were 0.05–80 and 0.5–120 μM, respectively, and the corresponding limit of detections (LODs) were 22.1 and 73.9 nM. As we proved the y-CDs have negligible cytotoxicity and excellent biocompatibility, further application to the fluorescence imaging of intracellular Fe3+ and PPi were conducted, suggesting the prepared y-CDs can be used to monitor Fe3+ and PPi variation in living cells. Overall, our developed y-CDs-based OFF-ON switch fluorescent probe has the advantages of simplicity, agility, high sensitivity and selectivity, which provides a promising platform for environmental and biology applications, and paves a new avenue for monitoring the hydrolysis process of adenosine triphosphate disodium salt (ATP) by detection of PPi in organisms.

Simultaneous visualization of lipid droplets and lysosomes using a single fluorescent probe

Lipid droplets (LDs) and lysosomes, as the important subcellular organelles, play vital roles in cell metabolism and physiology. The finding that LDs can be degraded by lysosomes through lipophagy demonstrated the communication between LDs and lysosomes. Thus, simultaneous visualization of LDs and lysosomes is extremely valuable for studying the LD-lysosome interplay. However, single fluorescent probe for simultaneous imaging LDs and lysosomes in live cells and tissues has been rarely reported. Herein, we developed a polarity-sensitive naphthalimide derivative LD-Lys as fluorescent probe with high photostability and low cytotoxicity. Due to its TICT feature, LD-Lys is highly sensitive to the nuance of polarity between LDs and lysosomes, and show strong and weak fluorescence, respectively. The simultaneous two-color imaging of LDs with bright yellow emission and lysosomes with weak red emission is also realized by using the Lambda mode of confocal laser scanning microscope. By monitoring the location changes, real-time tracking the movement of LDs and lysosomes in cells by LD-Lys could be visualized. Interestingly, the size, morphology and distribution of LDs and lysosomes in different tissues could be also visualized clearly. These excellent properties made LD-Lys a promising fluorescent agent for studying the LD-lysosome interplay and metabolism diseases.

Lanthanum mediated rutin yellow-fluorescent carbon dots as multifaceted sensing probes for the detection of calcium ions in melanoma and plant cells

Calcium (Ca2 +) as a signaling ion and intracellular second messenger plays a crucial role in living organisms for various cellular functions. In the present work, we have designed a novel yellow-fluorescent carbon dots (LERCDs) using lanthanum, ethylenediaminetetraacetic acid (EDTA), and rutin as precursors for the sensing of Ca2 + ions. In this sense, a combination of hydrothermal and reflux methods was adopted. The as-designed LERCDs display bright yellow color emission in the aqueous solutions with a high quantum yield (23.8%). The LERCDs showed excitation-independent emission property along with magnificent photostability and time stability. The LERCDs show potential fluorescence quenching response towards the Ca2+ ions in the concentration range of 0–25 μM with a detection limit of 2.19 μM. The LERCDs have studied for extracellular sensing of Ca2 + ions in both melanoma cell lines (A375) and onion epidermal cells by employing fluorescence microscopy. The LERCDs facilitate low cytotoxicity and superior biocompatibility features in A375 cells. The practicality of LERCDs was studied in biological samples like the human serum.

Synthesis and characterization of new yellow emitting mixed heteroleptic Ir(III) complexes with solution-processed phosphorescent organic light-emitting diodes

Two new yellow emitting heteroleptic Ir(III) complexes are designed and synthesized for solution-processed yellow phosphorescent organic light-emitting diodes (PHOLEDs) with the amide-bridge core as main ligand and 2-phenylpyridine (ppy) as the ancillary ligand, named as bis[5-(2-ethylhexyl)−8-(trifluoromethyl)benzo[c][1,5]naphthyrid in-6(5)one](phenylpyridine)iridium(III) (Ir-1) and bis[5-(2-ethylhexyl)benzo[c][1,5naphthyridin-6(5H)one](phenylpyridi ne)iridium(III) (Ir-2). Ir-1 and Ir-2 complexes emit bright yellow emission in dichloromethane solution at 298 K. The newly synthesized Ir(III) complexes reveals the higher quantum yields over 40% and relatively short triplet lifetimes (0.12–0.15 μs), both which warrant to both complexes highly electroluminescence active materials. Both Ir(III) complexes were utilized as emitters for yellow solution-process PHOLEDs and obtained better performance. In particular, maximum external quantum efficiency (EQEmax) and maximum current efficiency (CEmax) of of 13.38% and 39.54 cd A−1 with the CIE (x, y) coordinates of (0.45, 0.53) was achieved for Ir-1 based yellow device. Furthermore, PHOLEDs with Ir-2 as an emitter attained EQEmax of 11.71% and CEmax of 37.60 cd A−1 with good color purity.

KCa2Mg2V3O12: A novel efficient rare-earth-free self-activated yellow-emitting phosphor

The development of efficient near-ultraviolet (near-UV) excitable inorganic phosphors is highly important for application in near-UV-pumped white light-emitting diodes (LEDs). Herein, we reported on a novel efficient rare-earth-free yellow-emitting KCa2Mg2V3O12 vanadate phosphor. These phosphors were prepared by using a conventional high-temperature solid-state reaction method. Photoluminescence study revealed that KCa2Mg2V3O12 phosphor exhibited a broad excitation band in the 250−420 nm wavelength range with a peak at 346 nm, owing to the absorption of [VO4]3− groups. Upon 346 nm excitation, KCa2Mg2V3O12 phosphor showed bright yellow emission in the 400−800 nm range with a maximum at 540 nm and a full width at half maximum of 161 nm. Such self-activated broadband yellow luminescence was attributed to the 3T2→1A1 and 3T1→1A1 transitions of [VO4]3− groups. The Commission Internationale de l´Eclairage (CIE) color coordinates were calculated to be (0.3741, 0.4679), which were located in the yellow region in the CIE chromaticity diagram. Impressively, the internal quantum efficiency of KCa2Mg2V3O12 phosphor was measured to be as great as 41 %. In addition, the temperature-dependent emission spectra were recorded, and the activation energy Ea was determined to be 0.366 eV. The newly developed KCa2Mg2V3O12 phosphor might have application potential as color converter in white LEDs.

Selective and sensitive fluorescent nanoprobe based on AgInS2-ZnS quantum dots for the rapid detection of Cr (III) ions in the midst of interfering ions

We herein report a novel eco-friendly method for the fluorescent sensing of Cr (III) ions using green synthesized glutathione (GSH) capped water soluble AgInS2-ZnS (AIS-ZnS) quantum dots (QDs). The as-synthesized AIS-ZnS QDs were speherical in shape with average diameter of ∼2.9 nm and exhibited bright yellow emission. The fluorimetric analyses showed that, compared to Cr (VI) ions and other 20 metal ions across the periodic table, AIS-ZnS QDs selectively detected Cr (III) ions via fluorescent quenching. In addition, AIS-ZnS QDs fluorescent nanoprobes exhibited selective detection of Cr (III) ions in the mixture of interfering divalent metal ions such as Cu (II), Pb (II), Hg (II), Ni (II). The mechanism of Cr (III) sensing investigated using HRTEM and FTIR revealed that the binding of Cr (III) ions with the GSH capping group resulted in the aggregation of QDs followed by fluorescence quenching. The limit of detection of Cr (III) ions was calculated to be 0.51 nM. The present method uses cadmium free QDs and paves a greener way for selective determination of Cr (III) ions in the midst of other ions in aqueous solutions.

Time-resolved and fluorescence excitation-emission matrix measurements of lanthanide (Gd3+, Tb3+ and Dy3+) doped silver-zinc borate glasses

This paper reports the time-resolved luminescence and excitation-emission matrix measurements of three different lanthanide ions Gadolinium, Gd3+ (GdG), Terbium, Tb3+ (TbG) and Dysprosium, Dy3+(DyG) doped silver-zinc borate glasses. The GdG and TbG glasses were excited at 267 nm and 371 nm, respectively, and time-resolved luminescence measurements used to evaluate how the randomness of the network can influence the lanthanide ion emission. The GdG glass exhibited ultraviolet radiation (UVR) at around 310 nm with a 6P7/2 → 8S7/2 transition. Similarly, a sharp band at 545 nm with a 5D4 → 7F5 transition provided a bright green coloured emission from the TbG glass. To further elucidate the Dy3+ emission, steady-state luminescence (SSL), excitation-emission matrix (EEM) studies and decay associated spectra (DAS) were obtained. These showed a bright yellow emission transition (4F7/2 → 6H9/2), 571 nm composed of species with decay times of 0.062, 0.148, 0.337 and 0.701 ms. Among them, an ideal decay time was observed at 0.701 ms along with a dependency of the DyG glass lifetimes on the emission intensity.

Luminescent Cu(I) complex with bis(indazol-1-yl)phenylmethane as chelating ligand

The cationic Cu(I) complex [Cu(N^N)2]+, where N^N is bis(indazol-1-yl)phenylmethane, was synthesized as chloride or tetrafluoroborate salt by reacting CuCl or [Cu(NCCH3)4][BF4] with bis(indazol-1-yl)phenylmethane under mild conditions. The structure of [Cu(N^N)2]Cl was ascertained by single-crystal X-ray diffraction. The complex exhibited bright yellow emission upon excitation with near UV and violet light, attributed to triplet LLCT/MLCT transitions on the basis of experimental data and computational outcomes.

Spatiotemporal Dynamics of Aggregation‐Induced Emission Enhancement Controlled by Optical Manipulation

AbstractWe present spatiotemporal control of aggregation‐induced emission enhancement (AIEE) of a protonated tetraphenylethene derivative by optical manipulation. A single submicrometer‐sized aggregate is initially confined by laser irradiation when its fluorescence is hardly detectable. The continuous irradiation of the formed aggregate leads to sudden and rapid growth, resulting in bright yellow fluorescence emission. The fluorescence intensity at the peak wavelength of 540 nm is tremendously enhanced with growth, meaning that AIEE is activated by optical manipulation. Amazingly, the switching on/off of the activation of AIEE is arbitrarily controlled by alternating the laser power. This result means that optical manipulation increases the local concentration, which overcomes the electrostatic repulsion between the protonated molecules, namely, optical manipulation changes the aggregate structure. The dynamics and mechanism in AIEE controlled by optical manipulation will be discussed from the viewpoint of molecular conformation and association depending on the laser power.

Spatiotemporal Dynamics of Aggregation-Induced Emission Enhancement Controlled by Optical Manipulation.

We present spatiotemporal control of aggregation-induced emission enhancement (AIEE) of a protonated tetraphenylethene derivative by optical manipulation. A single submicrometer-sized aggregate is initially confined by laser irradiation when its fluorescence is hardly detectable. The continuous irradiation of the formed aggregate leads to sudden and rapid growth, resulting in bright yellow fluorescence emission. The fluorescence intensity at the peak wavelength of 540 nm is tremendously enhanced with growth, meaning that AIEE is activated by optical manipulation. Amazingly, the switching on/off of the activation of AIEE is arbitrarily controlled by alternating the laser power. This result means that optical manipulation increases the local concentration, which overcomes the electrostatic repulsion between the protonated molecules, namely, optical manipulation changes the aggregate structure. The dynamics and mechanism in AIEE controlled by optical manipulation will be discussed from the viewpoint of molecular conformation and association depending on the laser power.

Dual‐Guest Functionalized Zeolitic Imidazolate Framework‐8 for 3D Printing White Light‐Emitting Composites

AbstractMetal–organic frameworks (MOFs) stand as a promising chemically active host scaffold for the encapsulation of functional guests, because they could enhance luminescent properties by molecular separation of fluorophores in the nanoscale pores of the MOF crystals. Herein, simultaneous nanoconfinement of two fluorophores is shown, namely, A) fluorescein and B) rhodamine B in the sodalite cages of ZIF‐8, constructed under ambient conditions through a simple one‐pot reaction. A novel Dual‐Guest@MOF system is reported, termed: A+B@ZIF‐8, which overcomes the intrinsic problem of aggregation‐caused quenching in the solid state to gain bright yellow emission under UV irradiation. Subsequently, this yellow emitter is combined with a blue‐emitting photopolymer resin, to yield a 3D printable luminescent composite material. A number of 3D printable composite objects for converting UV into warm white light emission are designed, achieving a high quantum yield of ≈44% in the solid state 3D printed form. This research instigates the bespoke application of a vast range of 3D printable Guest@MOF designer composites targeting energy‐saving lighting devices, smart sensors, and future optoelectronics.

Plant habitat-conscious phosphors: Tuneable luminescence properties of Dy3+-doped Ca8ZnY(PO4)7 phosphors by co-dopants Mg2+ and B3+

Outdoor lighting and other lighting systems can disrupt natural plant growth habits. Thus, LED lighting that is not detrimental to plant growth is required. In our study, Dy3+-doped Ca8ZnY(PO4)7:Dy3+ phosphor with enhanced luminescence properties caused by the co-dopants Mg2+ and B3+ were synthesised. The samples had multiple excitation peaks, indicating they are excited by either near-ultraviolet (n-UV) or blue chips. All samples exhibited bright narrow yellow and blue emission corresponding to the transitions of Dy3+ ions with 4F9/2→6H13/2 and 4F9/2→6H13/2, respectively. Moreover, doping with Mg2+ and B3+ enhanced the luminescence intensity, reaching 113.6 and 119.7%, respectively. In addition, the luminescence emission intensity at 150 °C was maintained at approximately 95% of the initial value at 25 °C, and its thermal stability increased by 123%. Devices assembled with an n-UV chip (388 nm) and the as-obtained CZMYP:Dy3+ phosphor emitted a bright warm white light and simulated outdoor dark lighting for tobacco cultivation, indicating that the as-prepared phosphor is an excellent candidate material for plant habitat-conscious phosphors.

DMEDA]PbCl4: a one-dimensional organic lead halide perovskite with efficient yellow emission

By using a simple room temperature solution reaction, we prepared a new type of one-dimensional (1D) hybrid lead halide [DMEDA]PbCl4. The compound gives a bright yellow emission with efficient photoluminescence quantum efficiency (PLQE) and optical stability.

Novel luminescent homo/heterometallic platinum(ii) alkynyl complexes based on Y-shaped pyridyl diphosphines.

A series of dinuclear platinum(ii) alkynyl complexes [Pt2L2(C[triple bond, length as m-dash]CC6H4R-4)4] (R = H 1, CH32, But3) and unusual tetranuclear Pt(ii)-Ag(i) clusters [Pt2Ag2L(C[triple bond, length as m-dash]CC6H4R-4)6] (R = H, 4; CH3, 5; But, 6), together with novel polymer crystals [Pt2Ag2L(C[triple bond, length as m-dash]CC6H5)6]∞ ([4]∞), were synthesized by a self-assembly reaction between [NBu4]2[Pt(C[triple bond, length as m-dash]CC6H4-R-4)4] and [Ag6L6]6+ (L = 4-(3,5-(diphenylphosphine)phenyl)pyridine). These complexes were characterized by using a range of spectroscopic techniques and complexes 1, 3, 5, and [4]∞ were analysed by X-ray crystallography. Each platinum atom of the Pt(ii)-Ag(i) clusters shows an unusual asymmetric distorted square planar geometry with three alkynyl groups and one bridging L phosphorus atom. Dinuclear complexes 1-3 demonstrate solid-state weak blue luminescence, while tetranuclear Pt(ii)-Ag(i) clusters 4-6 show intense blue-green or yellow-green emission. Furthermore, the crystalline samples of polymer [4]∞ display bright yellow emission (518 nm) that is significantly red-shifted as compared to monomer crystal 4.

Lead‐Free Sodium–Indium Double Perovskite Nanocrystals through Doping Silver Cations for Bright Yellow Emission

AbstractLead‐free halide perovskite nanocrystals (NCs) have drawn wide attention for solving the problem of lead perovskites toxicity and instability. Herein, we synthesize the direct band gap double perovskites undoped and Ag‐doped Cs2NaInCl6 NCs by variable temperature hot injection. The Cs2NaInCl6 NCs have little photoluminescence because of dark self‐trapped excitons (STEs). The dark STEs can be converted into bright STEs by doping with Ag+ to produce a bright yellow emission, with the highest photoluminescence quantum efficiency of 31.1 %. The dark STEs has been directly detected experimentally by ultrafast transient absorption (TA) techniques. The dynamics mechanism is further studied. In addition, the Ag‐doped NCs show better stability than the undoped ones. This result provides a new way to enhance the optical properties of lead‐free perovskites NCs for high‐performance light emitters.

Lead-Free Sodium-Indium Double Perovskite Nanocrystals through Doping Silver Cations for Bright Yellow Emission.

Lead-free halide perovskite nanocrystals (NCs) have drawn wide attention for solving the problem of lead perovskites toxicity and instability. Herein, we synthesize the direct band gap double perovskites undoped and Ag-doped Cs2 NaInCl6 NCs by variable temperature hot injection. The Cs2 NaInCl6 NCs have little photoluminescence because of dark self-trapped excitons (STEs). The dark STEs can be converted into bright STEs by doping with Ag+ to produce a bright yellow emission, with the highest photoluminescence quantum efficiency of 31.1 %. The dark STEs has been directly detected experimentally by ultrafast transient absorption (TA) techniques. The dynamics mechanism is further studied. In addition, the Ag-doped NCs show better stability than the undoped ones. This result provides a new way to enhance the optical properties of lead-free perovskites NCs for high-performance light emitters.