White Light-emitting Diode Device Research Articles

Light-induced synthesis of Highly stable CsPbCl3:Mn2+@mSiO2 nanocomposites for white Light-Emitting Diodes

All-inorganic perovskite nanocrystals (NCs) exhibit great promise in optoelectronics and photovoltaics. However, their intrinsic low-thermal/oxygen/moisture stability and the rigorous synthesis procedures have limited the practical applications. Here, we present a facile, one-step, light-induced method to synthesize CsPbCl3:Mn2+ NCs at room temperature by using carbon tetrachloride (CCl4) as the halide source. The corresponding formation mechanism of CsPbCl3:Mn2+ NCs is revealed, where CsPbCl3:Mn2+ NCs are formed through the direct incorporation of [MnCl6]4− octahedral into the perovskite lattice during the nucleation and growth process. Additionally, we demonstrate the in-situ growth of CsPbCl3:Mn2+ NCs within mesoporous silica (mSiO2) spheres to form CsPbCl3:Mn2+@mSiO2 nanocomposites via the light-induced method, resulting in a remarkable improvement in high-temperature and long-time stability. As a prototype experiment, a white light-emitting diode (WLED) device is constructed using CsPbCl3:Mn2+@mSiO2 nanocomposites, which exhibits a bright white-light emission with the CIE chromaticity coordinate of (0.352, 0.340). It is anticipated that light-induced synthesis method provides a straightforward strategy for synthesizing multifunctional halide perovskite nanocrystals and nanocomposites for versatile applications.

Emergent updates and future directions on white light emitting diodes based on luminous lead-free halide perovskites

Lead halide perovskites possess exceptional optical and electrical properties, yet their inherent toxicity and instability present significant challenges for practical application in white light-emitting diodes (WLEDs) for displays and lighting. Alhough, techniques such as reduced dimensionality, transition metal doping, and protective encapsulation have shown some success in enhancing stability. These advancements remain limited and do not fully meet the requirements for real-world WLED devices. This featured letter delves into the emerging advancements in lead-free halide perovskite WLEDs includes color-conversion WLEDs, and single-emissive-layer WLEDs. Despite significant advancements, issues with stability, efficiency, and scalable fabrication still exist. Future approaches centre on methods to enhance these features, opening the door for lead-free perovskite WLEDs to become commercially viable and bringing in a new age of environmentally friendly lighting options. Additionally, this featured letter provides a comprehensive review of the current advancements and future possibilities in white light-emitting diodes based on lead-free halide perovskites materials. This letter serves as an invaluable resource for researchers, scientists, and engineers dedicated to advancing this field.

Anion regulation for surface passivation enables ultrahigh-stability perovskite nanocrystals.

All-inorganic perovskite CsPbBr3 nanocrystals (NCs) display high photoluminescence quantum yield and narrow emission, which show great potential application in optoelectronic devices. However, the poor environment stability of NCs will hinder their practical application. Herein, a series of ionic liquids with different anions (BF4-, Br-, and NO3-) were used as a sole capping ligand to synthesize NCs. Among the three samples, 1-hexadecyl-3-methylimidazolium tetrafluoroborate ([C16MIM]BF4) capped NCs have the highest stability in light, thermal, and water, possibly attributing to the in situ passivation of bromine vacancy via pseudohalogen BF4- and tight binding of ionic liquid ligands and lead atoms. In addition, green-emission [C16MIM]BF4 NCs were used to assemble a white light-emitting diode device, and it possessed a wide National Television System Committee color gamut of 124.5% and a stable emission peak at high driving currents of 380 mA. This work paves the way for resurfacing perovskite NCs with ultrahigh stability, thereby driving the perovskite NC display industry closer to real-world application.

High color rendering index WLEDs enabled by multi-band tuning of InP quantum dots

Quantum dots (QDs) represent a significant class of fluorescent materials, offering the potential to reduce power consumption and enhance the color rendering index (CRI) of white light-emitting diode (WLED) devices. However, the presence of toxic elements such as Cd and Pb in traditional fluorescent QDs limits their widespread commercial application. Compared to the broad emission characteristics of environmentally friendly AgInS2 and CuInS2 QDs, the narrower linewidth of InP-based core-shell QDs is advantageous for developing WLED devices with a higher CRI. In this study, we employed a multistage heating method to synthesize a series of amino-phosphine-based InP/ZnSe core-shell QDs, which exhibited emission wavelengths ranging from 535 to 650 nm, narrow emission linewidths of 43-47 nm, and high photoluminescence quantum yields of 60%-80%. Subsequently, six different color QDs are used to fabricate a WLED device. The best WLEDs show not only bright warm light (correlated color temperature = 3323 K) with a maximum luminous efficacy of 74.1 lm W-1, but also excellent color quality (CRI Ra = 93, as well as R9 = 94.8, and R13 = 97.1). These results indicate remarkable progress in InP-based WLEDs for high-quality lighting applications.

Spectral characteristics and luminescence applications of Eu3+-activated fluorosilicate Na2MgGd2[SiO3]4F2

This work reports the luminescence spectra and application of novel Eu3+-doped Na2MgGd2[SiO3]4F2 phosphor. The X-ray powder diffraction confirmed the pure phase formation of the samples with the monoclinic space group P21/c (No:14). The phosphors demonstrated efficient red emission at 613 nm from the electric dipole transitions 5D0→7F2. The optimal doping concentration was found to be approximately 25 mol%. Na2MgGd2[SiO3]4F2:0.25Eu3+ exhibits a high quantum efficiency (QE) of 57 % with excellent thermal stability and pure chromaticity. Red- and the white light-emitting diode devices were packaged using InGaN chips and Na2MgGd2[SiO3]4F2:0.25Eu3+. The fabricated WLED has CIE coordinates of (x = 0.33, y = 0.34), which are very close to the white point in the National Television System Committee (x = 0.33, y = 0.33). The color rendering index (CRI, Ra) and correlated color temperature (CCT) of the WLED are 91 and 4400 K, respectively. The results show that as a red luminescent phosphor, it is a potential candidate for the preparation of near-UV/blue InGaN-based WLEDs.

Mn2+ doped aluminum-rich spinel transparent ceramic phosphor with higher performance for wide color-gamut backlight display

Due to the great potential of narrow-band green-emitting phosphors for wide color-gamut white light-emitting diodes (WLED) backlight displays, there is great interest in finding host materials with the desired luminescent properties and high quantum efficiency. Herein, a series of Mg0.98-xAl2(1+x/3)O4: 0.02Mn2+ (x = 0, 0.125, 0.25) powders were synthesized using high-temperature solid-phase reactions, followed by a combination of pressureless sintering and hot isostatic pressure sintering to fabricate transparent ceramic phosphors. The crystal structure refinement, NMR spectroscopy, and photoluminescence results show tetrahedral coordination of Mn2+ ions and an increase in cation vacancies and disorder with increasing x. These transparent ceramics exhibit narrow-band green emission, which shifts from 523 to 520 nm with increasing x. The Mg0.855Al2.08O4: 0.02Mn2+ ceramic sample has an in-line transmittance of over 80 % above 500 nm and internal quantum efficiencies as high as 96.2 %. The luminous intensity of the Mg0.855Al2.08O4: 0.02Mn2+ ceramic remains above 88.6 % at 425 K compared to room temperature, with a thermal conductivity of 12.4 W·m−1·K−1. A WLED device fabricated using the Mg0.855Al2.08O4: 0.02Mn2+ ceramic, K2SiF6:Mn4+ phosphors, and a blue chip show a wide color gamut of 126 % National Television System Committee standard. The results show that Mn2+-doped aluminum-rich spinel transparent ceramics have great potential for application in wide color gamut WLED backlight devices.

Full-Visible-Spectrum White LEDs Enabled by a Blue-Light-Excitable Cyan Phosphor.

Efficient blue-light-excitable broadband cyan-emitting phosphors may yield full-visible-spectrum white light-emitting diodes (WLEDs) with ultrahigh color rendering (Ra > 95). However, this requires closing the "cyan gap" in the 480-520 nm region of the visible spectrum, which is challenging. Herein, a well-performed cyan-emitting garnet phosphor Ca2LuAlGa2Si2O12:Ce3+ (CLAGSO:Ce3+) is reported. Under 430 nm excitation, the optimal CLAGSO:5%Ce3+ compound exhibits a broadband cyan emission (peak, 496 nm; bandwidth, 102 nm) with a high internal quantum efficiency of 85.6% and an excellent thermal resistance performance (69.1% at 423 K). Importantly, this as-prepared cyan-emitting phosphor provides sufficient cyan emission and enables filling the well-known so-called "cyan gap" between the blue LED chip and the commercial Y3Al5O12:Ce3+ (YAG:Ce3+) yellow phosphor. Impressively, a WLED device fabricated with the optimal CLAGSO:5%Ce3+ sample shows a low correlated color temperature (4053 K) and an ultrahigh color rendering index (Ra = 96.6), as well as an excellent luminous efficacy (74.09 lm W-1). These results highlight the importance of blue-excited broadband cyan-emitting phosphors in closing the cyan gap and enabling human-centric full-visible-spectrum warm WLED devices for high-quality solid-state lighting.

Up-conversion luminescence and multimodal temperature sensing behaviors in the visible and infrared region of Er3+ and (Er3+, Yb3+) ions in Ca3Ta2Ga3O12 phosphors

Ca3Ta2Ga3O12 - CTGG ceramic phosphors doped with xEr3+ ions, x = (0.1, 1, 3, 5, 7, and 9 at.%) and (5Er, yYb), y = (0.1, 1, 3, 5, and 7 at.%) were investigated. The emission spectra of Er3+ ions were measured under 973 nm and 1550 nm excitations and the optimal concentrations of Er3+ and (Er3+, Yb3+) ions allowing to obtain the maximum emission intensities in the visible range were determined to be 5Er and (5Er, 5Yb), respectively. The best results in terms of correlated color temperature (CCT) and color purity (CRI) were obtained under λex = 973 nm. High values of CCT (between 5000 K and 6000 K) and CRI (in the range of 80 - 92) parameters indicate their potential as efficient materials for white light-emitting diode devices. The temperature dependence of Er3+ luminescence in 5Er:CTGG and (5Er, 5Yb):CTGG samples was investigated by the luminescence intensity ratio for different thermally coupled (TCLs) and non-thermally coupled (NTCLs) levels and the fluorescence lifetime. The highest value of the relative thermal sensitivity parameter (Sr) for 5Er:CTGG sample, Sr = 1.41 % K-1 at 325 K, was obtained from TCLs (2H11/2/4S3/2) under λex = 973 nm. For (5Er, 5Yb):CTGG sample, the highest values of Sr were obtained as follows: Sr = 1.77 % K-1 at 325 K from TCLs (2H11/2/4S3/2), Sr = 1.19 % K-1 at 150 K from TCLs (4I13/2(2)/4I13/2(3)), and Sr = 0.62 % K−1 at 450 K from 4S3/2 lifetime, under λex = 973 nm, and Sr = 1.23 % K-1 at 325 K from TCLs (2H11/2/4S3/2) and Sr = 1.21 % K-1 at 325 K from NTCLs (2H11/2/4F9/2) under λex = 1550 nm. These results indicate that 5Er:CTGG and (5Er, 5Yb):CTGG ceramic phosphors have high potential for applications in the field of optical temperature sensors.

Unraveling the Ultrasonic-Assisted Synthesis of Green-Emitting CsPbBr3@Cs4PbBr6: Reaction Process, Luminescence Property, and Display Application.

The pursuit of stable and highly emissive perovskite materials has garnered increasing attention in optoelectronic applications. Green-emitting CsPbBr3@Cs4PbBr6, as a green-emissive material in the solid-state form, has great potential as a color conversion material for full-color displays. However, it is a challenge to achieve mass preparation under ambient conditions. Meanwhile, the formation mechanism is ambiguous. This study reports a ligand-free and rapid mass synthesis of nanomicrosized CsPbBr3@Cs4PbBr6 solid via an ultrasonic-assisted method. The synthesized CsPbBr3@Cs4PbBr6 solids exhibit uniform morphology, high stability, and solid-state quantum efficiency of approximately 55%. Moreover, the transformation mechanism from Pb-Br complexes in the synthesis process is fully investigated by monitoring the phase and spectral evolution. By employing it as a green emitter, the obtained white light-emitting diode (LED) device shows high performance with a correlation color temperature of 7635 K and a wide color gamut of 123% NTSC. This study offers a low-cost and simple operation mass production method for solid-state perovskite powders with excellent chemical stability. Additionally, it provides new insights into the formation mechanism of highly efficient perovskite materials and promotes their practical applications.

Realizing Stable Luminescence in Antimony Doped Hybrid Tin(IV) Chloride toward Full Spectrum WLED and Anticounterfeiting Applications.

The outstanding optical properties empower Sb3+-doped zero-dimensional hybrid metal halides as cutting-edge luminescent materials. In this research, we present an efficient hybrid tin chloride, TEA2SnCl6:Sb3+ (TEA = tetraethylammonium), with broad dual emission bands peaking in the blue and orange regions that arise from the singlet and triplet state emissions of [SbCl5]2-, respectively. TEA2SnCl6:Sb3+ demonstrates a high photoluminescence quantum yield (PLQY) of 83.5% under 328 nm excitation, while 358 nm light induces an orange emission with a PLQY of 92.5% and a low thermal quenching behavior (73.9% at 423 K). Benefiting from the appealing luminescence properties of TEA2SnCl6:Sb3+, a full spectrum white light-emitting diode (WLED) device and an anticounterfeiting model were constructed, affirming the potential use of Sb3+-doped TEA2SnCl6 hybrid metal halide in versatile application fields.

Dual-functional application of Ca2Ta2O7:Bi3+/Eu3+ phosphors in multicolor tunable optical thermometry and WLED

A series of Bi3+/Eu3+ co-doped Ca2Ta2O7 (CTO:Bi3+/Eu3+) phosphors were prepared by high-temperature solid-state method for dual-emission center optical thermometers and white light-emitting diode (WLED) device. By modulating the doping ratio of Bi3+/Eu3+ and utilizing the energy transfer from Bi3+ to Eu3+, the tunable color emission ranging from green to reddish-orange was realized. The designed CTO:0.04Bi3+/Eu3+ optical thermometers exhibit significant thermochromism, superior stability, and repeatability, with maximum sensitivities of Sa = 0.055 K−1 (at 510 K) and Sr = 1.298% K−1 (at 480 K) within the temperature range of 300−510 K, owing to the different thermal quenching behaviors between Bi3+ and Eu3+ ions. These features indicate the potential application prospects of the prepared samples in visualized thermometer or high-temperature safety marking. Furthermore, leveraging the excellent zero-thermal-quenching performance, outstanding acid/alkali resistance, and color stability of CTO:0.04Bi3+/0.16Eu3+ phosphor, a WLED device with a high Ra value of 95.3 has been realized through its combination with commercially available blue and green phosphors, thereby demonstrating the potential application of CTO:0.04Bi3+/0.16Eu3+ in near-UV pumped WLED devices.Graphical abstract

A new zero-dimensional hybrid antimony halide of (C25H46N)2SbCl5 with dual-emission and high quantum-efficiency for light-emitting application

Zero-dimensional (0D) organic-inorganic hybrid metal halides (OIHMHs) have received extensive attention due to their excellent photoelectric properties. Herein, a new 0D OIHMH single crystal, (C25H46N)2SbCl5, has been synthesized by slow antisolvent diffusion. In this crystal structure, C25H46N+ (C25H46N+ = Cetyldimethylbenzylammonium cations) cations separated SbCl52− to form a 0D square pyramid structure. (C25H46N)2SbCl5 single crystals (SCs) manifest bright orange-yellow dual-emission bands at 472 and 616 nm, while having a high photoluminescent quantum yield of 97.5 %. The lifetime of high energy (HE) emission and low energy (LE) emission at room temperature is 9.73 ns and 4.61 μs, respectively. Based on lifetime differences and temperature-dependent spectra, the HE emission band is ascribed to singlet self-trapped excitons (STEs), while the LE emission band with a broad full width at half maxima of 136 nm can be attributed to triplet STEs. (C25H46N)2SbCl5 appeared anti-thermal quenching behavior. In accordance with the luminescence characteristics of (C25H46N)2SbCl5, a warm white light-emitting diode device was fabricated with the correlated color temperature of 3410 K, the relevant color coordinate of (0.41, 0.39) and the color rendering index of 95.1, demonstrating (C25H46N)2SbCl5 a promising phosphor for solid-state light-emitting application.

A novel Na2Ca2Si3O9: Tb3+ glass ceramic with high luminescence efficiency and robust thermal stability for white LED lighting application

Given the increasing demand for white light emitting diode (WLED) lighting devices marked by high color rendering indices (CRI) and exceptional thermal stability, there is a burgeoning interest in developing emitters with enhanced performance. Rare earth (RE) ion-activated glass ceramics (GCs) have garnered significant attention due to their outstanding physicochemical and thermal stability, alongside their high luminescence efficiency. In this study, the GCs doped with Tb3+ ions in the Na2O-CaO-SiO2 system matrix were synthesized, incorporating Na2Ca2Si3O9 nanocrystals averaging less than 100 nm in size. Notably, these GC materials demonstrated superior luminescence efficiency in the green light emission under the irradiation of 376 nm light compared to the parent glass. A comprehensive analysis of fluorescence spectra revealed an impressive internal quantum efficiency of 87.34 % for this Tb3+-doped GC. Furthermore, the GC retained 90 % and 84 % of the initial luminescence intensity at 150 °C and 200 °C in comparison to the luminescence level at room temperature, showcasing exceptional resistance to fluorescence thermal quenching. Verification experiments utilized UV LED chip, (Sr, Ca)AlSiN3: Eu2+ red phosphor, BaMgAl10O17: Eu2+ blue phosphor, and Tb3+-doped GC to encapsulate the WLED device, achieving a remarkable CRI of 92, CIE chromaticity coordinates (0.3547, 0.3361), and a correlated color temperature (CCT) of 4550K. In conclusion, the experimental outcomes unequivocally underscore the significant application potential of these Tb3+-doped GCs in the territory of warm WLED lighting.

Microwave synthesis of composite of AgInS2 quantum dots and zeolitic imidazolate framework-8 for application in white light emitting diodes

Preparation of AgInS2 quantum dots (AIS QDs) with high photoluminescence quantum yield (PLQY) and thermal stability remains an important challenge. In this paper, AIS QDs were successfully introduced into zeolitic imidazolate framework-8 (ZIF-8) by microwave-assisted hydrothermal method. Due to the effective isolation of the ZIF-8, the AIS QDs avoid the concentration quenching when they were assembled into white light emitting diodes (WLEDs) devices as color conversion materials. More importantly, the generation of ZnS layer between the interfaces of AIS QDs and ZIF-8 can efficiently improve the optical performance of AIS QDs, resulting in the fluorescence lifetime extended to 470.05 ns. Meanwhile, the PLQY of AIS/ZIF-8 composite reached up 34.30 % when microwave hydrothermal heating at 120 °C for 60 min with AgIn/Zn=1/3, which was higher than that of the pristine AIS QDs as 25.30 %. Finally, the WLED devices were fabricated by combining AIS/ZIF-8 composite fluorescent powder with (Ba, Sr)Si2O2N2:Eu2+ phosphors and blue LED. At 20 mA, the AIS/ZIF-8 based WLED shows the luminous efficiency (LE) of 44.54 lm/W, correlated color temperature (CCT) of 4242 K and color rendering index (CRI) of 89.1. Moreover, the Commission International de L'Eclairage (CIE) was (0.36, 0.35), indicating the WLED emited warm white light. The present strategy aims at enhancing the optical performance of AIS QDs, which also may trigger the development of QDs-based WLED.

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.

A prime red phosphor Ca3Gd(AlO)3(BO3)4:Eu3+ with high color purity for low color temperature pc-WLEDs

A series of excellent thermal stability red phosphors Ca3Gd(AlO)3(BO3)4:Eu3+ were synthesized by conventional solid-state reaction method. Through the fluorescence spectrometer, the research results make clear that this phosphor has a best excitation wavelength of 396 nm, and 0.7 mol% of doping is optimal. The interaction between ions causes a concentration-quenching phenomenon when the doping concentration is too high. Under the excitation of 396 nm ultraviolet light, there is a significant emission peak at 623 nm due to the energy level transition of 5D0→7F2 in the outer layer of the fluorescent powder. The color purity of the Ca3Gd0.3(AlO)3(BO3)4:0.7Eu3+ is 98.8 %, which means the corresponding red light emitted can effectively compensate for the missing red light component in white light-emitting diodes(WLEDs). The operating temperature of WLED typically hovers around 150 degrees Celsius. At such temperatures, the luminous efficiency of fluorescent powders remains remarkably resilient, peaking at 94.84 % relative to room conditions. Even when the temperature surges to 200 degrees Celsius, the luminous efficiency of fluorescent powders persists at an impressive 88.87 %. The energy band gap of Ca3Gd0.3(AlO)3(BO3)4:0.7Eu3+ is up to 5.05 eV, which further demonstrates its excellent thermal stability. Ca3Gd0.3(AlO)3(BO3)4:0.7Eu3+ phosphor used in the WLED device emits warm white light (CCT = 3628 K, CRI = 87.4). As a result of these results, the phosphor can be used as an excellent red light component in pc-WLEDs.

In-situ passivation and anchoring of perovskite quantum dots on KSF:Mn phosphor for liquid crystal display

Perovskite quantum dots (PQDs) hold immense potential for application in backlight liquid crystal display (LCD) owing to their narrow emission spectra, tunable luminous wavelength along with high photoluminescence quantum yield. However, their poor stability severely impedes the practical application of PQDs in optoelectronic devices. Here, we prepare KSF@PQDs composites by in-situ generation of green-emitting MAPbBr3 PQDs on the surface of treated KSF:Mn red phosphors. The surface treatments on KSF:Mn are employed for realization of in-situ passivation and anchoring of MAPbBr3 through chemical interaction between the NH2 group on KSF:Mn and Pb2+ on PQDs, which enables high luminescence intensity, narrow spectral width and simultaneously high photostability of PQDs. Moreover, the ratio of green-to-red emission intensity in KSF@PQDs can be easily modulated by changing APTES content during the surface treatment of KSF:Mn. Further, white light-emitting diode devices consisting of InGaN chip and KSF@PQDs composite achieve luminous efficiency of 41.6 lm·W−1, as well as wide color gamut of 116.6 % for National Television Systems Council standard and 87.2 % for Rec.2020 standard, which paves the way for the application of high stability PQDs in wide color gamut LCD.

Enhanced color rendering index and thermal stability of Ca2GdNbO6: Dy3+ phosphors by co-doping Sm3+ ions

Nowadays, white light-emitting diodes (WLEDs) converted from single-phase white light-emitting phosphors are a popular subject in solid-state lighting. Dy3+ is one of the most widely used activator ions in single-phase white light-emitting phosphors. However, its application in solid-state lighting is limited due to the lack of a red light component. Therefore, this work synthesized single-phase white light-emitting Ca2GdNbO6: 0.05Dy3+, ySm3+ (CGNO: 0.05Dy3+, ySm3+) phosphors with a double perovskite structure. A detailed study was conducted on the occupancy of co-doped Dy3+-Sm3+ ions in the CGNO lattice and the microstructure of the sample. Simultaneously, the luminescence performance, concentration quenching mechanism, energy transfer, and thermal stability of CGNO:0.05Dy3+, ySm3+ phosphors were discussed. The results indicate that the phosphors have stable physical and chemical properties and excellent optical properties. Under 363 nm excitation, emission peaks of both Dy3+ and Sm3+ were observed in the emission spectrum, indicating that Sm3+ compensates for the insufficient red light component in the samples. In addition, the CIE chromaticity coordinates (CIE) of the CGNO: 0.05Dy3+, ySm3+ samples and the luminescence stability in water were studied. Finally, a WLED device with a high color rendering index Ra = 85.4) and low correlated color temperature (CCT = 3135 K) was prepared by combining a 365 nm chip with the CGNO: 0.05Dy3+, 0.05Sm3+ phosphor. The research confirmed that single-phase white light-emitting CGNO: 0.05Dy3+, ySm3+ phosphors have potential application prospects in the field of WLEDs.

Synthesis, structural and optical properties of a novel double perovskite Gd[formula omitted]MgTiO[formula omitted]: Dy[formula omitted] phosphors for LED applications

Dy3+ doped Gd2MgTiO6 (GMT) phosphors were were fabricated using the high temperature solid state method in this study. Fluorescence, UV-visible spectrometer, X-ray photoelectron spectrometer, and Transient fluorescence spectrometer. The results show that the structures of the series of phosphors belong to the monoclinic crystal system, and Dy3+ was successfully incorporated into the GMT host without affecting its structure. The samples emitted extremely strong blue and yellow light, which are the transitions derived from 4H9/2 to 6H15/2 (482 nm) and 6H13/2 (575 nm) levels, respectively. The sample shows obvious effects of concentration, GMT: 0.11Dy3+ phosphor has the best photoluminescence (PL) intensity 7.148×105, lifetime is 0.16 ms, and an internal quantum efficiency (IQE) is 2.1%. The Dy3+ doped sample has a larger energy band gap of 4.11 eV. The prepared samples exhibit color coordinates in proximity to that of standard white light, which indicates that the phosphor GMT: Dy3+ can be applied to white light phosphors and light-emitting diode (LED) devices.

Supramolecular Sequential Light-Harvesting Systems for Constructing White LED Device and Latent Fingerprint Imaging.

The fabrication of supramolecular light-harvesting systems (LHS) with sequential energy transfer is of significance in utilizing light energy. In this study, we report the non-covalent self-assembly of a sequential LHS by pillar[5]arene-based host-guest interaction in water and its applications in white light-emitting diode (LED) device and latent fingerprint imaging. The host-guest complex WP5 G self-assembles into nanoparticles in water and shows enhanced aggregation-induced emission (AIE) effect. The nanoparticles can be further used to construct sequential LHS with fluorescent dyes 4,7-di(2-thienyl)-benzo[2,1,3]thiadiazole (DBT) and sulforhodamine 101 (SR101). Impressively, the system shows white-light emission when the molar ratio of WP5 G/DBT/SR101 is 1100/2/16. The material can be coated on a LED bulb to achieve white-light emission. In addition, the sequential LHS exhibit multicolor fluorescence including red emission, which have been successfully applied to high-resolution imaging of latent fingerprints. Therefore, we demonstrated a general strategy for the construction of sequential LHS in water based on macrocyclic host-guest interaction and explored its multi-functional applications in white-light LED device and imaging of latent fingerprints, which will promote future development and application of supramolecular LHSs.