Cyan Light Research Articles

Study on the structure, energy transfer, and color-tunable photoluminescence of the stable BaY2Si3O10: Bi/Tb/Sm phosphors

With the growing concern about energy consumption, white light-emitting diodes(wLEDs), as the fourth generation of lighting sources, are highly scrutinized by researchers. A series of Bi3+/Tb3+/Sm3+ (co)doped BaY2Si3O10 phosphors were prepared by traditional solid-state method, and the phase purity was analyzed by X-ray diffraction. In this work, Bi3+/Tb3+/Sm3+ theoretically occupies the Ba/Y sites, and this conjecture is also proved by spectral analysis. Under near ultraviolet (nUV) light excitation, Bi3+/Tb3+/Sm3+ is respectively used as the blue (3P1 → 1S0)/green (5D4 → 7Fj)/red (4G5/2 → 6Hj) luminescence center. Due to the energy transfer (ET) efficiency between Bi3+/Sm3+ is not ideal, Tb3+ is introduced as a bridge to improve the ET efficiency of the whole system to achieve spectral tunability and application in wLEDs. And at different excitation wavelengths, Bi3+ emits a wide range of blue to cyan light because it occupies two cation sites. We selected a proper excitation wavelength and obtained an emission spectrum covering the whole visible region. The CIE color coordinates (0.3487, 0.3313), the correlated color temperature (CCT, 4773.61 K), quantum efficiency (QE, 47.62 %), and thermal stability (T50 = 537 K) of BaY2Si3O10: Bi3+/Tb3+/Sm3+ are discussed in depth, Lu3+ was used instead of Y3+ to improve the thermal stability of BYS. Its excellent luminescence performance indicates that this phosphor has potential applications in nUV wLEDs.

Harnessing the inherent photoluminescence of Ba2MgTeO6 double perovskite phosphor for visible to near infrared pc-LED applications

Phosphor-converted LEDs (pc-LEDs) emitting in the visible region based on undoped tellurate double perovskites have not been explored till now. A cyan-emitting pc-LED is fabricated using the host Ba2MgTeO6 double perovskite for the first time. The as-fabricated cyan LED emits light in the visible region with the maximum emission at 484 nm. The obtained CIE coordinates of (0.26, 0.37) ensure a cyan light, and LED exhibits superior color stability even at higher input drive current. An attempt to develop a white emitting phosphor was done by substituting Eu3+ ions into the Ba2MgTeO6 matrix. Followed by this, a phosphor converted LED emitting in the bluish white region was fabricated by combining near UV chip and BMTO: 0.02 Eu3+ phosphor. Further, an inherent near-infrared (NIR) luminescence in Ba2MgTeO6 is also discovered and it originates from the 3T1u, 3A1u – 1A1g electronic transitions within the Te4+ ions. Upon 367 nm excitation, Ba2MgTeO6 exhibits strong broadband NIR emission, which spans from 780 nm to 1150 nm with a maximum emission at 889 nm and full width at half maximum (FWHM) of about 115 nm. Finally, an efficient pc-LED emitting in the NIR region is fabricated using the intrinsic near-infrared luminescence observed in the Ba2MgTeO6 phosphor. The pc-LED covering the near infrared region can be potentially used for various applications, including plant cultivation, biosensors, night vision cameras, etc.

Axial length reduction and choroidal thickening with short-term exposure to cyan light in human subjects.

Given the potential role of light and its wavelength on ocular growth, this study investigated the effect of short-term exposure to red, cyan and blue light on ocular biometry in humans. Forty-four young adults and 20 children, comprising emmetropes and myopes, underwent 2-h sessions of cyan (507 nm), red (638 nm) and broadband white light on three separate days via light-emitting glasses. Additionally, young adults were exposed to blue light (454 nm) on an additional day. Axial length (AL) and choroidal thickness (CT) were measured in the right eye before the light exposure (0 min), after 60 and 120 min of exposure and 30 min after light offset using an optical biometer and optical coherence tomographer, respectively. Compared to broadband light, exposure to red light resulted in a significant increase in AL (mean difference between white and red light at 120 min, +0.007 mm [0.002]), but no significant change in CT, while cyan light caused a significant AL reduction (-0.010 mm [0.003]) and choroidal thickening (+0.008 mm [0.002]) in young adults (p < 0.05). Blue light caused a significant decrease of -0.007 mm (0.002) in young adult eyes at 60 min (p < 0.05). In children, cyan light led to a significant reduction in AL (-0.016 mm [0.004]) and strong sustained choroidal thickening (+0.014 mm [0.004]) compared to broadband light at 120 min (p < 0.05). The effects of cyan light on AL and CT were found to be stronger in myopic young adults and emmetropic children. The opposing effects of red and cyan light on ocular biometry were similar between the two age groups (p > 0.05). Exposure to cyan light resulted in AL reduction and choroidal thickening in both young adults and children. Further research is needed to determine the application of these results in developing interventions for myopia control.

Broadband spectral cyan emission phosphor for full-spectrum LED caused by interstitial site occupation

The phosphor with a highly condensed, rigid framework structure and a single crystallographic site often exhibit symmetrical narrow-band emission. It is challenging to achieve broadband emission by doping Eu2+ ions in similar structures. Here, we propose to control the occupation and quenching concentration of Eu2+ ions in a single-site matrix Sc2Si2O7 to increase efficiency and precise regulation of luminescence spectra substantially. The analysis of photoluminescence spectroscopy through steady-state, transient-state, and Gaussian fitting techniques has discovered two emission centers despite the presence of a single rare-earth substitution site. The theoretical calculations and bond valence sum subsequently prove that Eu2+ ions prefer substituting the Sc3+ and interval sites to emit intense cyan light. Under 340 nm excitation, broad cyan-emission (FWHM = 115 nm) is exhibited with a high quantum yield of 60.67 %. The present phosphor exhibits pronounced thermal stability, and the emission intensity can still keep 68.3 % at 170 °C compared to that at atmospheric temperature. The Sc2Si2O7: Eu2+ phosphor boasts exceptional potential as a highly efficient cyan component in full-spectrum WLEDs. By replacing the blue light component commonly found in WLEDs, the intelligent and healthy alternative Sc2Si2O7: Eu2+ phosphor can effectively decrease the harmful blue light. This work also highlights the critical need to analyze local phosphor distortions upon rare-earth substitution, especially in single crystallographic site structures.

Garnet-type cyan-green-emitting SrLu2Ga1.5Al2.5SiO12:Ce3+ phosphor with high quantum efficiency, thermal stability, and water resistance for blue-excited WLEDs

Nowadays, high-quality phosphor-converted white light-emitting diodes (pc-WLEDs) ought to include cyan-emitting phosphors allowing for full-spectrum light similar to sunlight. Herein, we report a garnet-structured Ce3+-doped SrLu2Ga1.5Al2.5SiO12 (SLGASO) phosphor that significantly compensates for the absence of cyan light, known as the “cyan cavity”. The SLGASO host crystallizes into a cubic structure with the space group. The cell parameters were determined using Rietveld refinement. Under 430 nm blue excitation, SLGASO:Ce3+ emits intense cyan-green light in the 450‒700 nm wavelength range. The representative SLGASO:0.07Ce3+ phosphor has an internal quantum efficiency (IQE) of 95.4% and excellent thermal stability, remaining 92.7% of its initial emission intensity at 152 °C. After 155 d of immersion in water, the luminous intensity of SLGASO:0.07Ce3+ remains constant, confirming its waterproofness. Furthermore, a pc-WLED device with luminous efficiency (LE) of 101.58 lm/W, color rendering index (Ra) of 91, correlated color temperature (CCT) of 4536 K, and Commission Internationale de L’Eclairage (CIE) chromaticity coordinates of (0.3555, 0.3390) was fabricated by combining as-prepared cyan-green-emitting SLGASO:0.07Ce3+, yellow-emitting Y3Al5O12:Ce3+ (YAG:Ce3+), and red-emitting (Ca,Sr)AlSiN3:Eu2+ phosphors, as well as a 450 nm blue chip. These findings indicate that SLGASO:0.07Ce3+ phosphor can bridge the cyan gap and improve the performance of as-fabricated full-visible-spectrum WLEDs.

Tunable Narrowband to Wideband emission of Mn2+, Eu2+ Co-doped GdMgAl11O19 for multifunctional applications

As the widespread application of white light-emitting diodes (WLEDs) in lighting field and liquid crystal display (LCD) backlight, the development of phosphors toward multifunctional applications is considered to be an inevitable tendency. In this work, multi-color light emissions have been realized in Eu2+ and Mn2+-activated magnetoplumbite-type GdMgAl11O19 (GMAO) along with adjustable photoluminescence properties. Significantly, a promising narrow-band green light emission can be achieved by Mn2+-activated GMAO with the full width at half maximum (FWHM) of 27 nm, and such narrow emission band makes the as-prepared WLED device reach 121 % of National Television Standards Committee (NTSC), which can act as an ideal LCD backlight. On the other hand, the broad cyan light can be achieved in Eu2+-activated GMAO. Moreover, multi-color light emissions have been realized in Eu2+ and Mn2+ co-doped GMAO, and the energy transfer from Eu2+ to Mn2+ ions was established. Benefitting from the broad band cyan light emission of Eu2+ ion, a promising WLED device with high color rendering index (CRI) of 90 has been fabricated by using Eu2+ and Mn2+ co-doped sample. The result indicates the multifunctional applications of the GMAO modulated by Eu2+ and Mn2+ activators.

Enhancing the cyan light emission of Ba9Lu2Si6O24:Ce phosphors by crystal-site engineering for full spectrum lighting

Filling the cyan gap is the key element in achieving full-spectrum illumination using violet chip to excite red, green and blue phosphors. However, designing cyan phosphors suitable for violet light excitation with excellent performance remains challenging. Herein, a novel cyan phosphor Ba9Lu2-x-nSi6O24:xCe (n-BLS:Ce) with multiple crystal sites of Ba2+ and Lu3+ for Ce3+ ions was designed and prepared via crystal-site engineering. The Ce3+ ions at Ba2+ sites emit ultraviolet light at 385 nm under 325 nm ultraviolet light excitation, and the Ce3+ ions at Lu3+ sites emit cyan light at 485 nm under 395 nm violet light excitation. The favorable occupation of Ce3+ ions at Lu3+ sites could be realized by introducing Lu vacancies. Significantly, the cyan light emission intensity of Ba9Lu1.4Si6O24:0.3Ce (n0.3-BLS:Ce) with Lu vacancies is effectively improved by 47 % compared to Ba9Lu1.7Si6O24:0.3Ce (n0-BLS:Ce) without Lu vacancies. And the emission intensity at 150 °C retains 96 % of that at room temperature. The color rendering index increases from 87.9 to 94.5 after supplementing Ba9Lu2-x-nSi6O24:xCe cyan phosphor in w-LEDs devices combining commercial red, green, and blue phosphors with a violet chip, indicating its potential practical application in full-spectrum lighting. This work also provides new ideas for the design and development of new and efficient high-quality light-emitting materials.

Tunable Multicolor Emission and High Thermal Stability in Single‐Matrix Luminescent Crystals Based on Calcium Perovskites for Advanced Solid‐State Lighting Applications

AbstractThe development of environmentally friendly full‐inorganic luminescent materials with tunable emission properties and exceptional thermal stability is of paramount importance for applications in optoelectronic devices, solid‐state lighting, and anti‐counterfeiting technologies. In this study, a novel luminescent crystal based on calcium perovskites Cs2CaCl4·2H2O (CCCH) are explored using a hydrothermal method. Simultaneous co‐doping of CCCH with Sn2+ and Mn2+ yields the s‐p transition‐induced cyan light from Sn2+ and d‐d transition‐induced yellow light from Mn2+. It demonstrates effective energy transfer from self‐trapped exciton (STE) of matrix CCCH and s‐p transition of Sn2+ to Mn2+, synergizing composite white lights with tunable colors. Furthermore, the incorporation of Sn2+ into CCCH introduces a red shift from blue to cyan emission with a remarkable enhancement in luminescent intensity by a factor of 12 times. The crystal orbital Hamiltonian populations (─COHP) calculations revealed the crucial role of Mn2+ in lattice stability, as evidenced by the decomposition temperature exceeding 305 °C for CCCH:Sn2+,Mn2+ whereas 210 °C for undoped CCCH matrix. This research provides a comprehensive investigation of the luminescent properties of CCCH:Sn2+,Mn2+ crystal, holding significant promise for practical technological advancements in lighting and anti‐counterfeiting technologies.

Suppressing Self‐Oxidation of Eu2+ in Li2CaSiO4 for Full‐Spectrum Lighting and Accurate Temperature Sensing

AbstractEu2+‐doped phosphors have attracted the great attention of researchers in the past decade. However, Eu2+ dopant in inorganic hosts often suffers from the self‐oxidation effect, therefore causing the attenuated emission intensity and quantum efficiency. In this regard, developing Eu2+ doped phosphors with the prohibited self‐oxidation effect of Eu2+ and increased thermal stability is urgently required. Herein, an innovative cyan‐light emitting Li2CaSiO4:Eu2+/Eu3+, Lu3+ (LCSO) phosphor is designed. Both experimental results and theoretical calculations demonstrate that adding Lu3+ restricts the self‐oxidation of Eu2+ into Eu3+, thus improving the emission of Eu2+. Meanwhile, the Lu3+ introduction brings out excellent thermal stability. Finally, an efficient WLED with a color temperature (CCT) of 4573 K and a high color rendering index (Ra) of 84.2 is obtained using the as‐prepared phosphor due to the perfect compensation of the cyan light. As the introduction of Lu3+ improves the stability of Eu2+, a much greater difference in PL decay rate between Eu2+ and Eu3+ in LCSO is reached, thereby improving their sensitivity in temperature sensing. The strategy of Lu3+ introduction for prohibiting the self‐oxidation of Eu2+ for efficient and stable Eu2+ emission may stimulate some new ideas in designing high‐performance phosphors for more diverse applications.

Facile green synthesis of Zn doped MoO3 nanoparticles and its photocatalytic and photoluminescence studies

In the field of nanoscience, the use of plant components for the synthesis of nanoparticles (NPs) is currently gaining popularity and has several advantages over physicochemical methods. Murraya koenigii (MK) leaf powder was used as the green fuel in the effective synthesis of the Zinc-doped molybdenum trioxide (Zn-MoO3) NPs by the green combustion method. The green synthesized NPs were characterized using XRD, FTIR, SEM, EDAX, UV–Vis and Photoluminescence (PL) spectroscopy techniques. The XRD pattern revealed the presence of an orthorhombic phase. The Tauc relation was used to calculate the energy band gap value of the samples found to be between 2.9 and 3.1 eV. The prepared NPs emit cyan light. Latent fingerprint analysis has revealed more distinct patterns in the near UV region (365 nm) and is useful in forensic investigations. The Rose Bengal (RB) dye degradation experiments are carried out under UV light exposure. Zn-MoO3 NPs have greater degradation efficiency than pure MoO3 NPs. Up to 99 % dye degradation is achieved in 150 min. After 3 photocatalysis cycles, the recycling test detects only an 8% decrease in photocatalyst efficiency. The obtained results proved that Zn-doped MoO3 NPs are the most suitable photocatalyst for RB degradation.

Nanoactuator for Neuronal Optoporation.

Light-driven modulation of neuronal activity at high spatial-temporal resolution is becoming of high interest in neuroscience. In addition to optogenetics, nongenetic membrane-targeted nanomachines that alter the electrical state of the neuronal membranes are in demand. Here, we engineered and characterized a photoswitchable conjugated compound (BV-1) that spontaneously partitions into the neuronal membrane and undergoes a charge transfer upon light stimulation. The activity of primary neurons is not affected in the dark, whereas millisecond light pulses of cyan light induce a progressive decrease in membrane resistance and an increase in inward current matched to a progressive depolarization and action potential firing. We found that illumination of BV-1 induces oxidation of membrane phospholipids, which is necessary for the electrophysiological effects and is associated with decreased membrane tension and increased membrane fluidity. Time-resolved atomic force microscopy and molecular dynamics simulations performed on planar lipid bilayers revealed that the underlying mechanism is a light-driven formation of pore-like structures across the plasma membrane. Such a phenomenon decreases membrane resistance and increases permeability to monovalent cations, namely, Na+, mimicking the effects of antifungal polyenes. The same effect on membrane resistance was also observed in nonexcitable cells. When sustained light stimulations are applied, neuronal swelling and death occur. The light-controlled pore-forming properties of BV-1 allow performing "on-demand" light-induced membrane poration to rapidly shift from cell-attached to perforated whole-cell patch-clamp configuration. Administration of BV-1 to ex vivo retinal explants or in vivo primary visual cortex elicited neuronal firing in response to short trains of light stimuli, followed by activity silencing upon prolonged light stimulations. BV-1 represents a versatile molecular nanomachine whose properties can be exploited to induce either photostimulation or space-specific cell death, depending on the pattern and duration of light stimulation.

Performance study of Ca3Sc2Si3O12:Ce3+ cyan-green fluorescent converter for laser illumination

To address the problem of cyan-green light deficiency in fluorescent converters for laser diode (LD) illumination applications, Ca3-xSc2Si3O12:xCe3+ (CSS:xCe3+) cyan-green fluorescent ceramics and CSS:Ce3+ phosphor in glass (CSS:Ce3+-PiG) fluorescent converter were successfully prepared. Among them, the CSS:0.08Ce3+ cyan-green fluorescent ceramic and 20 wt% CSS:Ce3+-PiG fluorescent converter had the highest luminescence intensity. At 450 nm excitation, the emission spectra of both materials showed an asymmetric broadband band between 470 nm and 690 nm. And the two fluorescent converters are not appear of luminescence temperature quenching until more than 538 K. The performance of the white LDs synthesized with ceramic and PiG converters was investigated. Under different power excitation, the green emission intensity of both wLD is enhanced with increased incident laser power. The wLDs based on CSS:Ce3+ fluorescent ceramics have a luminous flux of 880 l m and the maximum luminescence efficiency of 176 l m/W at an incident power of 5 W. And the wLDs of PiG fluorescent converters have a maximum luminous flux of 584 l m and luminescence efficiencies of up to 117 l m/W. CSS:Ce3+ ceramics and CSS:Ce3+-PiG are green fluorescent converter with good luminescence performance and thermal stability. It will play an important role in the compensation of the cyan light in LD illumination.

Enhancing the UV resistance and flame retardancy of epoxy resin composites with fluorescent carbon dots

AbstractCarbon dots (CDs) are a novel class of carbon material which have gained widespread usages owing to their exceptional optical properties, low toxicity, and high biocompatibility. The nitrogen‐doped carbon dots (N‐CDs) using a normal curing agent of 4,4′‐diaminodiphenylmethane as resource was expected to not only have good compatibility with epoxy resin (EP), but also bring luminescent property to EP composites. It was interesting that the N‐CDs‐EP composites with 12.5 wt% addition exhibited a limiting oxygen index value of 31.4% and reached UL‐94 V‐1 grade, indicating a good flame retardancy. Compared with pure EP, the incorporation of N‐CDs formed more residual char and had extra smoke suppression effect. Besides, the N‐CDs‐EP composites exhibited a low transmittance less than 10% for the light wavelength below 490 nm. The N‐CDs contributed to the light shielding capabilities of the N‐CDs‐EP composites, which could effectively shield purple, blue, and cyan light. Furthermore, the mechanical properties including bending strength and impact strength, the dielectric property, and hydrophobicity of N‐CDs‐EP composites were also improved. The simple but effective modification strategy might be expected to be applied in many polymer systems.

Reversible Influence of Hemipiperazine Photochromism on the Early Development of Zebrafish Embryo.

This study explores the potential of controlling organismal development with light by using reversible photomodulation of activity in bioactive compounds. Specifically, our research focuses on plinabulin 1, an inhibitor of tubulin dynamics that contains a photochromic motif called hemipiperazine. The two isomeric forms, Z-1 and E-1, can partially interconvert with light, yet show remarkable thermal stability in darkness. The Z-isomer exhibits higher cytotoxicity due to stronger binding to α-tubulin's colchicine site. The less toxic E-1 form, considered a "pro-drug", can be isolated in vitro and stored. Upon activation by blue or cyan light, it predominantly generates the more toxic Z-1 form. Here we demonstrate that 1 can effectively photomodulate epiboly, a critical microtubule-dependent cell movement during gastrulation in zebrafish embryos. This research highlights the potential of photomodulation for precise and reversible control of cellular activities and organismal development.

Comparative Transcriptome Analysis Reveals the Light Spectra Affect the Growth and Molting of Scylla paramamosain by Changing the Chitin Metabolism.

Light is an essential ecological factor that has been demonstrated to affect aquatic animals' behavior, growth performance, and energy metabolism. Our previous study found that the full-spectrum light and cyan light could promote growth performance and molting frequency of Scylla paramamosain while it was suppressed by violet light. Hence, the purpose of this study is to investigate the underlying molecular mechanism that influences light spectral composition on the growth performance and molting of S. paramamosain. RNA-seq analysis and qPCR were employed to assess the differentially expressed genes (DEGs) of eyestalks from S. paramamosain reared under full-spectrum light (FL), violet light (VL), and cyan light (CL) conditions after 8weeks trial. The results showed that there are 5024 DEGs in FL vs. VL, 3398 DEGs in FL vs. CL, and 3559 DEGs in VL vs. CL observed. GO analysis showed that the DEGs enriched in the molecular function category involved in chitin binding, structural molecular activity, and structural constituent of cuticle. In addition, the DEGs in FL vs. VL were mainly enriched in the ribosome, amino sugar and nucleotide sugar metabolism, lysosome, apoptosis, and antigen processing and presentation pathways by KEGG pathway analysis. Similarly, ribosome, lysosome, and antigen processing and presentation pathways were major terms that enriched in FL vs. CL group. However, only the ribosome pathway was significantly enriched in up-regulated DEGs in VL vs. CL group. Furthermore, five genes were randomly selected from DEGs for qPCR analysis to validate the RNA-seq data, and the result showed that there was high consistency between the RNA-seq and qPCR. Taken together, violet light exposure may affect the growth performance of S. paramamosain by reducing the ability of immunity and protein biosynthesis, and chitin metabolism.

Enhanced Cyan Photoluminescence and Stability of CsPbBr3 Quantum Dots Via Surface Engineering for White Light‐Emitting Diodes

AbstractThe emission of cyan light (470‐500 nm) plays a vital role in the visible light spectrum and is essential for applications such as lighting, displays, and optical communication. Inorganic cesium lead bromide perovskite quantum dots (CsPbBr3 PQDs) have made significant progress in the field of luminescence materials and devices, however, the lack of techniques to obtain highly emissive and stable cyan‐emitting CsPbBr3 PQDs has limited their device applications. Here, it is demonstrated that the complete surface passivation by treatment of didodecyldimethylammonium bromide (DDAB) and lead bromide, which can enhance the photoluminescence and stability of cyan emitting CsPbBr3 PQDs. In particular, the photoluminescence quantum yield of CsPbBr3 QDs can be greatly improved from 10.5% to 83.8%. Through an effective PMMA passivation, the obtained stable and bright CsPbBr3 PQDs composite films as the cyan color converters can effectively emit the cyan light to fill the “cyan gap” of white light‐emitting diode (WLED). The color rendering index value of such WLED is remarkably enhanced from 73.6 to 82.5. This study paves the way for the application of PQD color converters in the next generation of full‐visible‐spectrum WLED lighting.

Observation of Visible Upconversion Luminescence of Soft Glass Multimode Fibers

This research investigates the visible upconversion luminescence which is induced by multiphoton absorption of soft glass fiber defects. The study of this phenomenon has thus far been restricted to standard silica fibers. We observed the emission of green and cyan light as a consequence of fiber material ionization. We investigate both the commercial ZBLAN step index and in-house-made tellurite nanostructured graded-index fibers. For the latter, the analysis of the luminescence signal permits us to determine the core and cladding refractive index difference. Upconversion luminescence is a powerful tool for characterizing soft glass fibers and a promising platform for innovative photonic technologies and mid-IR applications.

Two novel chiral AIEgens as coordination precursors: synthesis, structures and photophysical study

Two novel chiral molecules, (4S)-5,5-dimethyl-2-(4-oxo-4H-chromen-3-yl)thiazolidine-4-carboxylic acid (OCCA) and (4S)-5,5-dimethyl-2-(4-(1,2,2-triphenylvinyl)phenyl)thiazolidine-4-carboxylic acid (TPCA), were successfully synthesized by aldehyde amine condensation reaction, and their structures were characterized by 1H NMR and single crystal X-ray diffraction. The intensities of photoluminescence changed with the aggregation, exhibiting that OCCA and TPCA are aggregation-induced emission luminogens (AIEgens). After complete aggregation, OCCA emitted the purple-blue light at the peak of 388 nm and TPCA emitted the cyan light at the peak of 488 nm. The aggregation-induced emission (AIE) effects for OCCA and TPCA resulted from local state to twisted intermolecular charge transfer (TICT) and restriction of intramolecular motion (RIM), respectively. Other spectra including UV–vis, IR, and Raman spectra were also discussed in detail.

Structure modification and luminescence regulation in new violet light excitable Sr(2-y)BayY4La4(SiO4)6O2:xEu2+ phosphors via cation substitution.

Cyan-emitting phosphors are urgently needed to address the "cyan gap" in artificial full-spectrum lighting. In this research, a series of Sr(2-y)BayY4La4(SiO4)6O2:xEu2+ (0.005 ≤ x ≤ 0.08, 0.0 ≤ y ≤ 2.0) phosphors with tunable luminescence was synthesized. Through cation regulation, the luminescence color of Sr(2-y)BayY4La4(SiO4)6O2:xEu2+ can be adjusted from yellow to cyan. Crystal structure analysis revealed that Eu2+ ions simultaneously occupy [Sr1/Ba1Y1La1] and [Sr2/Ba2Y2La2] sites, resulting in multiple luminescence centers and a broadened emission spectrum. With increasing Ba2+ ion concentration, the PLE spectrum was red-shifted from 337 nm to 372 nm, and the excitation intensity in the violet region was significantly enhanced, making it more compatible with violet LED chips. Meanwhile, the PL spectrum was blue-shifted from 543 nm to 496 nm with increasing Ba2+ concentration, accompanied by an increase of about 10 times in the excitation and emission intensity. The optimized Ba2Y4La4(SiO4)6O2:0.02Eu2+ phosphor can be excited by violet light and emits bright cyan light effectively, which can be used to fill the "cyan gap". Eventually, a series of white LED devices was manufactured by combining the as-prepared luminescence-tunable phosphors with commercial phosphors. Among them, the 410 nm violet LED chip-based WLED(Ba2) device comprising Ba2Y4La4(SiO4)6O2:0.02Eu2+ exhibited the best electroluminescence performance, increasing the color rendering index from 82.0 to 98.6, verifying the compensation effect of the Ba2Y4La4(SiO4)6O2:Eu2+ phosphor on cyan light.

Enhanced detection of acrylamide using a versatile solid-state upconversion sensor through spectral and visual analysis

Acrylamide (AM) generally forms in high-temperature processes and has been classified as a potential carcinogen. In this study, we put forward a maneuverable solid-state luminescence sensor using polydimethylsiloxane (PDMS) as the matrix coupled with upconversion nanoparticles as the indicator. The core-shell upconversion nanoparticles emitting cyan light were uniformly encapsulated in PDMS. Then it was further modified with complementary DNA of AM aptamer. The nanocrystalline fluorescein isothiocyanate isomer (FITC), coupled with AM aptamer, was attached to the surface of PDMS. FITC effectively quenched the upconversion luminescence through fluorescence resonance energy transfer (FRET). The introduction of AM resulted in preferentially bound to aptamer caused the separation of the quencher and the donor, and led to luminescence recovery. The developed sensor was applied for both spectral and visual monitoring, demonstrating a detection limit (LOD) of 1.00 nM and 1.07 nM, respectively. Importantly, in the actual foodstuffs detection, there is no obvious difference between the results of this study and the standard method, which indicates the developed method has good accuracy. Therefore, this solid-state sensor has the potential for on-site detection using a smartphone device and an Android application.