Emission Color Research Articles

Multicolor luminescent rare-earth-free glass ceramic for thermal information indication

Temperature-dependent multicolor luminescent materials are widely used in optical temperature sensing and related applications. However, most of these materials derive their luminescence from the radiation transition of rare earth (RE) ions. Therefore, the development of RE-free luminescent materials is of great significance for RE resources and environmental protection. Here, we propose a novel RE-free multicolor luminescent glass-ceramic (GC) and offer a color regulation strategy for defect-induced luminescence. As the temperature rises, thermal expansion alters the state of the defects, causing the emission color to gradually shift from cyan-green to dark blue. This color shift is reversible, returning to the original color as the temperature decreases. Moreover, the GC retains 97.2 % of its luminescence intensity after being submerged in water for one year, highlighting its excellent physicochemical stability. A pattern label prepared by this GC, exhibits excellent luminescent color-temperature response, indicating its potential application in high-temperature information indication.

Impact of TBAI Doping on the Optical and Dielectric Features of PVC/MoO3/NiMoO4/PANI Polymer Composite for Optoelectronic and Energy Storage Applications

Poly (vinyl chloride, PVC)/MoO3/NiMoO4/polyaniline (PANI)/x wt% tetrabutylammonium iodide (TBAI) polymers were formed using casting and hydrothermal methods. The present study examined the nanocomposites’ structural, electrical, and optical features comprising PVC/MoO3/NiMoO4/PANI/x wt%TBAI polymers. X-ray diffraction and scanning electron microscopy were used to investigate the structure and morphology of different samples. The influence of different amounts of TBAI on the linear and nonlinear optical features of PVC/MoO3/NiMoO4/PANI/x wt%TBAI polymers was explored. Adding MoO3/NiMoO4/PANI.TBAI reduced the direct and indirect optical band gaps to their minimum values (3.88, 3.04) eV and (3.58, 2.13) eV, respectively. Doped polymer with MoO3/NiMoO4 has the highest refractive index value. Only PVC filled with MoO3/NiMoO4 exhibits the highest non-linear optical parameters within the visible range. The fluorescence intensity and emitted colors influenced by the kind of dopant. The dielectric constant and ac conductivity values of the host polymer were affected by the amount of TBAI. The maximum energy density value was observed in PVC/MoO3/NiMoO4/PANI/10 wt%TBAI polymer. The Cole-Cole plot demonstrated an irregular shift for doped samples relative to the undoped. The obtained results nominated the nanocomposite films of PVC/MoO3/NiMoO4/PANI/x wt%TBAI to be used in diverse electric and optoelectrical applications.

Inducing Multicolour emission in MEH-PPV/TiO2 nanocomposites

Fluorescence-based polymers have a wide variety of applications such as light-emitting diodes, optoelectronics, and biosensors. The present study endeavors towards the effect of TiO2 nanoparticles (calcined at various temperature) on the emission of Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) and to induce multicolor emission. The TiO2 nanoparticles synthesized by sol-gel method were calcined at 400°C and 600°C. In situ polymerization was adopted to synthesize MEH-PPV / TiO2 nanocomposites and the structural characteristics of the nanocomposites were studied using Fourier transformed Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The photo-physical characteristics of the nanocomposites were investigated using UV-Visible spectroscopy, Photoluminescence spectroscopy, and Fluorescence microscopy. TiO2 nanoparticles calcined at 400°C demonstrates anatase phase, whereas the particles calcined at 700°C exhibits mixed phase of rutile and anatase. The study reveal that calcination temperature has a strong impact on the morphology of the synthesized nanoparticles. The photoluminescence spectra reveal that the incorporation of TiO2 nanoparticles enhances the red orange emission intensity of MEH-PPV, additionally exhibits emission at multiple wavelengths. Fluorescence microscopy evidences multiple colour emission from MEH-PPV/TiO2 nanocomposites. The multiple emission in the polymer nanocomposite is arised from the oxygen vacancies present in anatase and rutile phases of TiO2 nanoparticle.

Super‐Sensitive Multi‐Modal Optical Manometer Based on Huge Pressure‐Induced Spectral Red‐Shift and Broadening of Mn2+ Emission Band in Green‐Emitting Zn2GeO4 Phosphors

AbstractTo overcome the small sensitivities of luminescent manometers, Mn2+‐activated Zn2GeO4 green‐emitting phosphors with admirable manometric characteristics are synthesized. The structural stability of the studied samples is theoretically and experimentally investigated. Moreover, as pressure elevates, a huge spectral red‐shift and a broadening of the emission band are observed in studied samples, contributing to color‐tunable luminescence, i.e., from green to yellow, and ultimately to orange–red. Specifically, when pressure increases to 6.76 GPa, the emission band centroid shifts from 535.9 to 634.9 nm, leading to a superior sensitivity of dλ/dp = 21.3 nm/GPa. Whereas, in the same operating pressure range, the full width at half maximum (FWHM) of the emission band rises from 32.3 to 102.9 nm, resulting in unprecedentedly high sensitivity of dFWHM/dp = 17.0 nm/GPa. Furthermore, through analyzing the pressure‐dependent color coordinates, a maximum sensitivity of 29.43% GPa−1 is achieved, when x‐coordinate is adopted. Additionally, the applicability of the developed manometer is confirmed by a simple uniaxial pressure experiments to showcase its practical use in industrial and daily‐life purposes. Notably, the designed sensor exhibits the highest pressure sensitivities reported to date in different modes, namely, emission band centroid, FWHM and color coordinate, making supersensitive multimodal optical manometry a reality.

Harvesting the tuning mechanism of strategic polychrome and white light emission in NapH dye based on excited state intermolecular proton transfer

Organic white light emitting (WLE) materials have sparked a research boom due to their promising applications in display devices, artificial lighting, and molecular sensors. However, the complex luminescence mechanism of full-spectra emitting materials has limited the development of white light materials with high stability and reproducibility. In this study, building on the full-spectra luminescent naphthimide dye (NapH) introduced by Xu et al., (Chin. Chem. Lett. 35(2024), 108348), we report the solvent-sensitive excited state proton transfer (ESPT) properties and white light emission mechanism in NapH. Our theoretical research results show that the ESPT process of NapH molecule is hindered in the low-polar solvent tetrahydrofuran (THF), so only the blue fluorescence from the Enol* is observed in the experiment. In contrast, in polar solvents such as water (H2O) and methanol (MeOH), the formation of strong intermolecular hydrogen bonds successfully initiates the ESPT process, leading to the dual fluorescence observed in experiments, with blue emission from the Enol* and red emission from the Nap anion. In essence, different solvent environments can adjust several emission colors. Furthermore, we theoretically verify that the optimal white light emission can be achieved when the mixed solvent ratio of dimethyl sulfoxide (DMSO) and dioxane (DIOX) is 5:5, which aligns well with experimental results. More importantly, we elucidate the specific WLE mechanism from multiple perspectives, including potential energy curves and electron spectra. Our work not only displays the interaction models of NapH molecule in various solvents, but also reveals the underlying luminescence mechanism, thus providing a valuable theoretical reference for the development and advancement of new white light materials.

Design and synthesis of dicyanoethylene derivatives functionalized with carbazole possessing the properties of obvious aggregation-induced emission and reversible high-contrast mechanofluorochromism

This study devotes to the design, preparation, and examination of two novel D-A structured molecules, designated as CCEDBF and BCCEDBF, which are derived from carbazole unit, dicyanoethylene segment, and dibenzofuran unit. The distinctive D-A molecular architectures and highly twisted spatial configurations of these compounds facilitate pronounced intramolecular charge transfer (ICT) while also imparting robust solid-state luminescence, exhibiting emission efficiencies of 0.518 and 0.739, respectively, and notable aggregation-induced emission (AIE) with AIE factors of 43 and 30. Significantly, both CCEDBF and BCCEDBF demonstrate reversible mechanofluorochromic (MFC) behavior characterized by high fluorescence contrast. Mechanical grinding of the initial powders results in a shift in their emission colors, transitioning from green and yellow-green to yellow and orange-red, respectively, alongside a corresponding shift in emission peaks from 525 nm to 536 nm–558 nm and 597 nm. Powder X-ray diffraction (PXRD) examination of the initially synthesized, mechanically processed, and vaporized samples reveals that the observed fluorescence color change is due to a structural transformation between ordered crystalline and disordered amorphous configurations induced by the application of the external force. The red shift in photoluminescence (PL) spectra post-grinding is attributed to a reduced band gap, driven by factors such as extended π-conjugation length, enhanced planar intramolecular charge transfer (PICT) effect, strengthened π-π interactions and exciton coupling, as well as the increase in the orbitals overlap between neighboring molecular. Moreover, the presence or absence of tert-butyl substituents attaching to the 3- and 6-positions of the carbazole units significantly impacts the photophysical properties of these materials.

Water‐Involved Carbon‐Nitrogen Triple‐Bond Monomer Based Polymerization toward Processable Functional Polyamides under Ambient Conditions

AbstractPolyamide plays a pivotal role in engineering thermoplastics. Constrained by the harsh conditions and arduous procedures for its industrial synthesis, developing facile synthesis of polyamides is still challengeable and holds profound significance. Herein, we successfully utilized water as one of the monomers to synthesize functional polyamides under ambient conditions. A powerful multicomponent polymerization of water, isocyanides, and chlorooximes was established in phosphate‐buffered saline. Soluble and thermally stable polyamides with high weight‐average molecular weights (up to 53 900) were obtained in excellent yields (up to 95 %). The polymerization exhibits unique polymerization‐induced emission characteristics, successfully converting non‐emissive monomers into unconventional emissive polymers. Notably, the resultant polyamides could undergo effective post‐modification via the hydroxyl‐yne click reaction. By incorporating various functional groups into the polyamide, its emission color could be fine‐tuned from blue to green and to red. Remarkably, the refractive index (n) of the polyamide at 589 nm could be increased from 1.6173 to 1.7227 and the Δn could be unprecedentedly as high as 0.1054 for non‐heavy atom‐containing polymers after post‐modification, and its micron‐thick films exhibited excellent transparency in the visible region. Thus, this work not only establishes a powerful polymerization toward novel polyamides but also opens up an avenue for their versatile functionalization.

Water-Involved Carbon-Nitrogen Triple-Bond Monomer Based Polymerization toward Processable Functional Polyamides under Ambient Conditions.

Polyamide plays a pivotal role in engineering thermoplastics. Constrained by the harsh conditions and arduous procedures for its industrial synthesis, developing facile synthesis of polyamides is still challengeable and holds profound significance. Herein, we successfully utilized water as one of the monomers to synthesize functional polyamides under ambient conditions. A powerful multicomponent polymerization of water, isocyanides, and chlorooximes was established in phosphate-buffered saline. Soluble and thermally stable polyamides with high weight-average molecular weights (up to 53 900) were obtained in excellent yields (up to 95 %). The polymerization exhibits unique polymerization-induced emission characteristics, successfully converting non-emissive monomers into unconventional emissive polymers. Notably, the resultant polyamides could undergo effective post-modification via the hydroxyl-yne click reaction. By incorporating various functional groups into the polyamide, its emission color could be fine-tuned from blue to green and to red. Remarkably, the refractive index (n) of the polyamide at 589 nm could be increased from 1.6173 to 1.7227 and the Δn could be unprecedentedly as high as 0.1054 for non-heavy atom-containing polymers after post-modification, and its micron-thick films exhibited excellent transparency in the visible region. Thus, this work not only establishes a powerful polymerization toward novel polyamides but also opens up an avenue for their versatile functionalization.

Achieving Controllable Thermochromic Fluorescence via Synergistic Intramolecular Charge Transfer and Molecular Packing

Thermochromic fluorescent materials (TFMs) have attracted significant attention due to their unique fluorescent colorimetric response to temperature. However, existing TFMs still suffer from weak stimulus responsiveness, broad temperature response ranges, uncontrollable emission color changes, and low quantum yields. In this study, we address these issues by designing and synthesizing three diketone‐boron complexes with distinct emission wavelengths (NWPU‐(2‐4)). Utilizing a molecular engineering strategy to manipulate intramolecular charge transfer transitions and molecular packing modes, our synthesized complexes exhibit efficient fluorescence emission in both solution and solid states. Moreover, their emission wavelengths are highly sensitive to environmental polarity. By incorporating these compounds into thermosensitive matrices of long‐chain alkanes, we produced TFMs with varied fluorescence emission peak variation ranges. Notably, the TFM based on NWPU‐4, owing to its strong charge transfer transitions and dense J‐aggregate packing configuration, not only exhibits intense fluorescence emission spanning the deep red to near‐infrared spectrum but also displays a remarkable 90 nm broad range of thermochromic properties. Ultimately, it was successfully applied to programmable, thermally controlled, multi‐level information encryption.

Reversible Emission Color, Brightness, and Shape Changes of AIEgen‐containing Bulk Polymers

AbstractBulk polymers generally exhibit faster response, higher shape‐deformation speed, and stronger mechanical properties than the hydrogels. However, it still remains a formidable challenge to enable bulk polymers to exhibit reversible changes in shape and fluorescence simultaneously. Herein, for the first time, the temperature‐responsive reversible changes in fluorescence color, brightness, and shape of semi‐crystalline poly(ε‐caprolactone) (PCL) network doped with a D‐A based aggregation‐induced emission luminogen (AIEgen) is realized. The fabricated flower‐like and dragonfly‐shaped actuators show reversible blooming‐closing and wing fanning behaviors, respectively, as well as reversible fluorescence‐changing effects. Notably, the response and shape‐deformation speed as well as mechanical properties of the system is much better than the reported hydrogels. Moreover, a smart switch is developed to demonstrate the potential applications. The stick fabricated by the sample can lift and release an object 1000 times larger than its weight, serving as a color‐changing artificial muscle. This material design strategy may shine light on the design and preparation of other reversible shape‐deformation polymers in combination with stimuli‐responsive luminescence‐changing AIEgens, such as mechanochromic, thermochromic, and photochromic luminogens.

Achieving Controllable Thermochromic Fluorescence via Synergistic Intramolecular Charge Transfer and Molecular Packing.

Thermochromic fluorescent materials (TFMs) have attracted significant attention due to their unique fluorescent colorimetric response to temperature. However, existing TFMs still suffer from weak stimulus responsiveness, broad temperature response ranges, uncontrollable emission color changes, and low quantum yields. In this study, we address these issues by designing and synthesizing three diketone-boron complexes with distinct emission wavelengths (NWPU-(2-4)). Utilizing a molecular engineering strategy to manipulate intramolecular charge transfer transitions and molecular packing modes, our synthesized complexes exhibit efficient fluorescence emission in both solution and solid states. Moreover, their emission wavelengths are highly sensitive to environmental polarity. By incorporating these compounds into thermosensitive matrices of long-chain alkanes, we produced TFMs with varied fluorescence emission peak variation ranges. Notably, the TFM based on NWPU-4, owing to its strong charge transfer transitions and dense J-aggregate packing configuration, not only exhibits intense fluorescence emission spanning the deep red to near-infrared spectrum but also displays a remarkable 90 nm broad range of thermochromic properties. Ultimately, it was successfully applied to programmable, thermally controlled, multi-level information encryption.

Multistimuli Luminescence and Anthelmintic Activity of Zn(II) Complexes Based on 1H-Benzimidazole-2-yl Hydrazone Ligands

Three novel Zn(II) mononuclear complexes with the general formula ZnL2Cl2 (L = 2-(4-R-phenylmethylene)benzimidazol-2-hydrazines; R-H (1), R-CH3 (2), and R-OCH3 (3)) were synthesized and fully characterized by various means. These complexes demonstrate excitation-dependent emission, which is detected by a change in the emission color (from blue to green) upon an increase in the excitation wavelength. Moreover complex 1 shows reversible mechanochromic luminescence behavior due to the reversible loss of solvated methanol molecules upon the intense grinding of crystals. In addition, 1 exhibits vapochromic properties, which originate from the adsorption methanol vapor on the crystal surface. The strengthening of anthelmintic activity at the transition from free hydrazones to zinc-based complexes is shown.

Marine eukaryote bioluminescence: a review of species and their functional biology

AbstractBioluminescence, the ability of organisms to produce visible light, has intrigued scientists for centuries. Studies have examined bioluminescence, using a wide range of approaches and organisms, from its ecological role to its underlying molecular mechanisms, leading to various applications and even a Nobel prize. Over the last ten years, an increasing amount of data has been collected leading to a growing number of recognized marine bioluminescent species. This review provides and describes a referenced listing of the eukaryotic luminous marine species, including information related to: (i) intrinsic versus extrinsic source of the bioluminescence, (ii) the color and maximum wavelength of emission, (iii) the bioluminescent system (substrate and enzyme) and the associated molecules, (iv) the availability of light organ/cell(s) pattern and histological structure, (v) the physiological control of the light production, and (vi) the demonstrated or suggested bioluminescent function(s). This listing provides basic information and references for researchers in or entering in the field of marine bioluminescence. Using a semi-quantitative approach, we then highlight major research gaps and opportunities and reflect on the future of the field.

Tunable Emission and Structural Insights of 6-Arylvinyl-2,4-bis(2'-hydroxyphenyl)pyrimidines and Their O∧N∧O-Chelated Boron Complexes.

In this study, we present the synthesis and photophysical characteristics of a novel series of 6-arylvinyl-2,4-bis(2'-hydroxyphenyl)pyrimidines. These compounds exhibit nonemissive properties attributed to the potential occurrence of a excited-state intramolecular proton transfer process from the OH groups to the nitrogen atoms of the pyrimidine ring. The introduction of an acid for protonation of the pyrimidine ring results in a significant enhancement of the fluorescence response, easily perceptible to the naked eye. Notably, these molecules serve as intriguing rigid O∧N∧O ligands for boron chelation. The incorporation of boron atoms promotes structural planarity, increases rigidity, and successfully restores fluorescence in both solution and the solid state. Moreover, the photoluminescence was found to be strongly influenced by the nature of the end groups on the arylvinylene fragment, allowing for the modulation of the emission color and covering the optical spectrum from blue to red. Strong emission solvatochromism was observed in various solvents, a finding that supports the formation of intramolecular charge-separated emitting states, particularly when terminal electron-donating groups are present in the structure. X-ray diffraction analysis enables the determination of inter- and intramolecular interactions, as well as molecular packing structures, aiding in the rationalization of distinct luminescent behaviors in the solid state. All experimental findings are elucidated through extensive density functional theory (DFT) and time-dependent DFT calculations.

Incorporation of ESIPT into pillar[5]arene for solid-state dual emission responsive to n-hexane vapor

Abstract Pillar[5]arene is a promising macrocyclic receptor of a chemical sensor showing shape-selective encapsulation of neutral molecules into the cavity, but the poor fluorescence properties remain a challenge. Herein, we report a pillar[5]arene coupled with 2-(2-hydroxyphenyl)benzoxazole (HBO), which displays bright fluorescence in both solution and the solid state. Owing to the excited-state intramolecular proton transfer (ESIPT) in the HBO moiety, greatly improved fluorescence is observed for the pillar[5]arene derivative in CHCl3 (Φlum = 11%) and powder form (Φlum = 25%). Moreover, the emission color changes from light green to blue when the powder sample is exposed to n-hexane vapor. The color change derives from variable dual emission via ESIPT and excimer-forming pathways, as suggested by fluorescence lifetime measurements at different wavelengths. Powder x-ray diffraction indicates that increased crystallinity and a small alteration in the solid-state structure leads to visible fluorescent chromism upon vapor encapsulation.

A red-emitting phosphor Na3AlF6:Mn4+: Green synthesis, optical characteristics, thermal stability and application in high-performance warm WLED

Mn4+-doped fluoride red phosphors have been widely used in warm WLEDs, but the preparation of such phosphor requires the use of a large amount of HF as a fluorine source and an acidic environment. How to reduce the excessive use of highly toxic HF in the preparation process and achieve green synthesis has become a hot research topic. Therefore, a simple green synthesis strategy is proposed in this work to synthesize a series of red-emitting phosphors Na3AlF6:Mn4+. The highly toxic HF solution is replaced by using a low toxicity reaction system (HCl/HNO3 + NH4F), which reduces the direct use of HF. X-ray powder diffraction, energy-dispersive X-ray spectrometer and scanning electron microscope are employed to determine the crystal structure, composition and morphology of all samples. Optical properties are characterized using excitation spectra, emission spectra and fluorescence lifetime curves. The calculation results indicate that the red-light has low correlated color temperature and the excellent color purity, and Na3AlF6 host can provide a strong crystal field environment for Mn4+. In addition, different aluminum sources and Mn4+ doping concentrations are used to explore the optimal preparation condition. The mechanisms of concentration quenching and thermal quenching have also been systematically explored. The stabilities of red-light emission intensity and color are investigated under the high temperature. The integral PL intensity at 423 K is 47 % of the initial value at 298 K. The activation energy, the chromaticity shift and the chromaticity coordinate variation are also systematically calculated. More importantly, a high-performance warm WLED with low correlated color temperature (CCT = 3296 K) and high color rendering index (Ra = 94.7) is achieved by using Na3AlF6:Mn4+ as a red-emitting material. Not only that, the warm WLED exhibits strong output stability under high driving current. The discovery of this work provides a comprehensive understanding for the rational design of high-performance Mn4+-activated fluoride red phosphors via a simple green synthesis strategy.

High‐Efficiency Circularly Polarized Luminescence Regulation of a Dye‐Doped Polymer Film by Acid/Aggregation

AbstractSmart materials with circularly polarized luminescence (CPL) tunable ability show great potential for advanced information storage and encryption. While an effective integration of high photoluminescence quantum yield (PLQY) and facile regulation of CPL property in thin films are of great significance, it is challenging due to the scarcity of suitable materials and complexity of systems. Herein, a novel acid‐responsive CPL tunable molecule is designed by combining an aggregation‐induced emission (AIE) component (TPE), an acid‐responsive luminophore (Rhodol), and a chiral aniline. Benefitting by the “AIE” effect of TPE and acid‐sensitive nature of Rhodol, the acidified molecule (S‐Rhodol‐TPE) exhibits a high PLQY even when doped in the polymer substrate at high concentrations. In addition, due to the fluorescence resonance energy transfer (FRET) process between TPE and Rhodol, the emission color of S‐Rhodol‐TPE can be easily regulated by the doped ratio and acidified degree of S‐Rhodol‐TPE in the polymer film. This work exhibits a unique approach to achieving smart CPL‐tunable films with high PLQYs and multiple emission color‐regulation properties, which can undoubtedly facilitate the progress of CPL tunable materials.

Analyzing JWST/NIRSpec Hydrogen Line Detections at TWA 27B: Constraining Accretion Properties and Geometry

Hydrogen lines from forming planets are crucial for understanding planet formation. However, the number of planetary hydrogen line detections is still limited. Recent JWST/NIRSpec observations have detected Paschen and Brackett hydrogen lines at TWA 27 B (2M1207b). Although classified as a planetary- mass companison (PMC) rather than a planet due to its large mass ratio to the central star, TWA 27 B’s hydrogen line emissions are expected to be same as the planetary one, given its small mass (≈5M J). We aim to constrain the accretion properties and accretion geometry of TWA 27 B, contributing to our understanding of hydrogen-line emission mechanisms common to both PMCs and planets. We conduct spectral fitting of four bright hydrogen lines (Pa-α, Pa-β, Pa-γ, Pa-δ) with an accretion-shock emission model tailored for forming planets. We estimate the mass accretion rate at Ṁ≈3×10−9MJyr−1 with our fiducial parameters, though this is subject to an uncertainty of up to factor of ten. Our analysis also indicates a dense accretion flow, n ≳ 1013 cm−3 just before the shock, implying a small accretion-shock filling factor f f on the planetary surface (f f ≲ 5 × 10−4). This finding suggests that magnetospheric accretion is occurring at TWA 27 B. Additionally, we carry out a comparative analysis of hydrogen-line emission color to identify the emission mechanism, but the associated uncertainties proved too large for definitive conclusions. This underscores the need for further high-precision observational studies to elucidate these emission mechanisms fully.

Advanced multicolor dynamic fluorescence anti-counterfeiting and encryption strategy based on light-induced reversible perovskite lattice distortion

Time-dynamic fluorescence encryption and anti-counterfeiting technology have garnered significant attention in the high-end information security field. However, developing tunable multicolor solid-state photoluminescent systems that are low-cost, easy to manufacture, scalable, and convenient to verify remains a considerable challenge. In this study, we finely tuned the luminescence behavior of CsCdCl3 all-inorganic perovskite crystals using a halogen doping strategy, resulting in reversible lattice distortion under UV light and endowing them with photoactivated luminescence properties to produce dynamic fluorescence. Upon the introduction of Br-, the optical properties of CsCdCl3 changed significantly, with the fluorescence emission color shifting from orange to white-green under UV irradiation. By adjusting the Br- doping ratio and UV irradiation intensity, the fluorescence color change time of CsCdCl3 can be controlled. Multiple cycle light exposure tests demonstrated that the luminescence properties of CsCdCl3 remained identical to the initial state, indicating high stability in response to UV stimulation. Consequently, we successfully realized advanced anti-counterfeiting and 4D code encryption modes based on dynamic fluorescence. The introduction of a time variable imparts extremely high security to these strategies. This work provides an exciting approach for designing information encryption materials with higher security requirements and offers a promising high-sensitivity UV detection material.

Rare earth Nd3+-doped organic-inorganic hybrid perovskite quantum dots for white LED

Lead halide perovskite quantum dots (QDs) have garnered significant attention due to their tunable band gaps, unique quantum confinement effects, and high photoluminescence quantum yields (PLQYs). Among them, Organic-inorganic QDs make them promising candidates for optoelectronic devices such as quantum dot light-emitting diodes (QLEDs), solar cells, lasers, and photodetectors. However, the toxicity of lead (Pb) has raised environmental and health concerns, hindering their industrial application. To alleviate concerns about heavy metals Pb, extensive research has been conducted on B-site doping and the development of lead-free perovskites. Herein, we firstly developed B-site doping strategy on organic-inorganic hybrid perovskite QDs via rare-earth elements. Neodymium (III) (Nd3+) doped FAPbBr3 QDs were prepared through the ligand-assisted reprecipitation method at room temperature. The B-site doping strategy could alleviate the heavy metal problem of Pb and modulate the band gap of FAPbBr3 QDs facilely. The results demonstrated that increasing the concentration of Nd³⁺ can change the emission of FAPbBr₃ QDs from pure green to deep blue. Specifically, we achieved highly pure blue emission (∼438 nm) with a full width at half maximum (FWHM) of 13 nm for Nd³⁺-doped FAPbBr₃ QDs. Time-resolved photoluminescence (TRPL) spectroscopy revealed a decrease in the lifetime of FAPbBr₃ QDs from 22.86 to 15.46 ns as the doping concentration increased. Additionally, we fabricated a white LED (WLED) utilizing blue-emitting Nd³⁺-doped FAPbBr₃, green-emitting FAPbBr₃ QDs, and red QDs, achieving a white emission color coordinate of (0.33, 0.36). This study pioneers the application of B-site rare-earth doping in organic-inorganic hybrid perovskite QDs, demonstrating that B-site composition engineering is a reliable strategy to further exploit the perovskite family for wider optoelectronic applications.