High Color-rendering Index Research Articles

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.

A Novel Broadband Green Phosphor La2W2O9: Bi3+, and Its Application in High Color-Rendering Index pc-WLED

Broadband green phosphors have important applications in overcoming the blue-green (cyan) 470–510[Formula: see text]nm gap of phosphor-converted white LED (pc-WLED) and achieving high color rendering index (CRI) white lighting. In this work, a broadband green phosphor La2W2O9: [Formula: see text]Bi[Formula: see text] was synthesized by solid-state method. The phase, morphology and luminescence properties of the series of phosphors were systematically studied. The results showed the La2W2O9: [Formula: see text]Bi[Formula: see text] green phosphor exhibits a wide emission band in the range of 400–800[Formula: see text]nm with full width at half-maximum (FWHM) of 164[Formula: see text]nm, filling the cyan gap and reaching its peak at 550[Formula: see text]nm. The phosphor exhibits broadband excitation, and the excitation range covers the wavelength region of 200–500[Formula: see text]nm, and matches well with commercial ultraviolet LED. With the obtained broadband green phosphor, commercial CaAlSiN3:Eu[Formula: see text] red phosphor, commercial BaMgAl[Formula: see text]O17:Eu[Formula: see text] blue phosphor, and a 365[Formula: see text]nm commercial chip, a warm white pc-WLED device with a high color-rendering index (Ra[Formula: see text]97.4, R1–R15[Formula: see text]90) and low correlated color temperature (CCT[Formula: see text]3610[Formula: see text]K) was fabricated. The results demonstrate the wide range of applications for La2W2O9:Bi[Formula: see text] phosphor in the field of premium warm white LED lighting.

Rational design of narrowband deep blue MR-TADF dendrimers for high performance solution-processed all fluorescence white OLEDs

Developing solution-processable deep-blue multiple resonances thermally activated delayed fluorescence (MR-TADF) is a formidable challenge. Here, we using a convergent synthesis process successfully developed a series of MR-TADF dendrimers based on C=O/N resonant core (QAO). The alkyl chain alternate-linked functional dendrons not only ensure the narrow-band deep-blue emission but also enable the dendrimers with aggregation-induced emission enhancement (AIEE) properties, which efficiently mitigate the aggregation-induced exciton quenching (ACQ) and obnoxious spectral redshift broadening effect. Notably, the solution-processed deep blue MR-TADF OLEDs achieved a maximum external quantum efficiency (EQE) of 13.5 % and CIE of (0.15, 0.12) with an electroluminescence peak below 450 nm. Further using such dendrimer as a sensitizer for white OLEDs resulted in an optimized high EQE of 18.9 % and a high color-rendering index (CIR) of 81.1 for two and three optical components of white emissions, which are among the highest values of previously reported solution-processed all-fluorescence white OLEDs. This is the first attempt to construct white OLED based on an MR-TADF emitter and the satisfactory results indicate that the flexible dendron engineering strategy can effectively develop high-performance narrow band deep-blue MR-TADF for wide-color gamut display and high CIR white OLEDs.

Zero-dimensional hybrid Cu(I) halide with cyan light emission for use in white light emitting diode

Traditional white light-emitting diode (WLED) is mainly depending on coating broadband yellow phosphors (520–700 nm) on blue emitting LED chip (440–460). However, too strong blue light and absence of cyan light results in incongruous emission strength and low color rendering index (CRI), which cause serious damage to retina of eye. To overcome these shortcomings, cyan light emitting phosphor is highly desirable for the full-visible-spectrum LED with high CRI, but bright cyan phosphor remains rare. Herein, a new 0D hybrid copper(I) halide of [TMPDA]Cu2I6 (TMPDA = N,N,2,2-tetramethyl-1,3-propylenediamine) single crystal is reported as a cyan light emitter with mominant emission wavelength at 489 nm, photoluminescence quantum yield of 26.66 % and large Stokes shift of 198 nm exceeding most of organic-inorganic metal halides. Remarkably, the single crystals display stable emission in various polar organic solvents and high temperature with sufficient emitting stability. More significantly, this 0D cuprous halide act as down-conversion cyan phosphor to fabricate WLED with a high CRI of 95 by reducing the cyan gap. In this study, we demonstrate an optical engineering strategy to prepare efficient cyan light emitting 0D cuprous halide and assembly high-performance WLED.

Synthesis and properties of naphthylamine derivative functionalized spiro-[fluorene-9,9′-xanthene] for single-component white light-emitting diodes

White light-emitting diodes (LEDs) with high color purity and color-rendering index have elicited much interest in many fields. In this work, a spirotype molecule SFX-PNA was designed and synthesized by combining a spiro[fluorene-9,9′-xanthene] (SFX) core with naphthylamine derivative functionalized at the 2,3′,6′,7-positions. Studies revealed that the highly twisted configuration allowed SFX-PNA to exhibit good thermal stability and a broad blue-emissive band (λem = 466 nm) in the solid state. In combination with the intrinsic yellow luminescence (λem = 556 nm) of commercially available GaN ultraviolet LED chips, a white LED with SFX-PNA as the phosphor was successfully obtained, which showed high color purity with Commission Internationale de L’Éclairage coordinates of (0.30, 0.33) and a color-rendering index of 86.

Binary Host-induced Exciplex Enabled High Color-Rendering Index of 94 for Carbon Quantum Dot-Based White Light-Emitting Diodes.

White light-emitting diodes (WLEDs) with high color-rendering index (CRI, >90) are important for backlight displays and solid-state lighting applications. Although the well-developed colloidal quantum dots (QDs) based on heavy metals such as cadmium and lead are promising candidates for WLEDs, the low CRI still remains a significant limitation. In addition, the severe toxicity of heavy metals greatly limits their widespread use. Herein, the study demonstrates low-cost and environmentally friendly carbon quantum dots (CQDs)-based WLEDs that exhibit a high CRI of 94.33, surpassing that of conventional cadmium/lead-containing QD-based WLEDs. This achievement is attained through the employment of a binary host-induced exciplex strategy. The high hole/electron mobility and suitable energy levels of the donor and acceptor give rise to a broadband orange-yellow emission stemming from the exciplex. As the host, the binary exciplex is capable of contributing blue and orange-yellow emission components while efficiently mitigating the aggregation-induced quenching of CQDs. Meanwhile, CQDs effectively address the deep-red emission gap, enabling the realization of CQDs-based WLEDs with high CRI. These WLEDs also exhibit a remarkably low turn-on voltage of 2.8V, a maximum luminance exceeding 2000cd m- 2, a correlated color temperature of 4976 K, and Commission Internationale de l'Eclairage coordinates of (0.34, 0.32).

Photoluminescence-Tunable organic phosphine cuprous halides clusters for X-ray scintillators and white light emitting diodes

Low-dimensional cuprous clusters demonstrate fascinating luminescent properties due to their uniquely diversified charge transfer excited states, which imply it could be ideal candidate for multifunctional applications, such as X-ray scintillators and white light emitting diodes (WLED). However, it is still challenge for low-dimensional cuprous clusters that how to regulate the emission performance to meet the requirements of the specific applications. In this work, we prepared a series of luminescent organic cuprous iodide clusters, (IPP)CuI2 and (IPP)2CuI3, which show tunable emission property by simply component regulation. The (IPP)CuI2 with IPP: CuI = 1: 0.75 show the best scintillator property with super-low detection limit of 62.29 nGy/s and high light yields of 75793.83 photons/MeV which is far beyond most organic copper halide scintillators. A series of clear digital radiography (DR) with high spatial resolution of 10.2 lp/mm and a reconstructed 3D model based on computed tomography (CT) were successfully obtained by the prepared scintillation screen. Moreover, the single-component WLED based on accurately component regulation (IPP)CuI2 with IPP: CuI = 1: 0.99 exhibits pure white emission with a high CRI (color rendering index) of 82. The luminescence mechanism of charge transfer excited states in tunable emission (IPP)CuI2 was also investigated. Our works not only provide a kind of ideal materials applied for high-performance single-component WLED and scintillator but also reveal the large potential of low-dimensional organic cuprous halides as luminescent material for multifunctional applications.

Luminescent properties of Y2LaCaGa3ZrO12: Bi3+, Al3+ cyan phosphors for application in white light emitting diodes

High-quality white light can be obtained from a mixture of blue, green, and red phosphors excited by ultraviolet chips. However, this approach suffers from the presence of a cyan gap in the emission spectra, which hinders further improvement in the color rendering index (CRI). The obvious solution to this problem should be the development of efficient ultraviolet-excited cyan phosphors to fill this gap. Therefore, a series of Y2LaCaGa3ZrO12: xBi3+ (x = 0–0.1) cyan phosphors were synthesized via high-temperature solid-state reaction method, and their properties were systematically characterized. The Bi3+ ion in Y2LaCaGa3ZrO12 exhibits dual-mode luminescence with emission bands peaking at 356 nm and 483 nm, originating from the 3P1→1S0 transitions of Bi3+ at different sites. The ultraviolet emission is attributed to Bi3+ occupying 8 coordination sites, while the cyan emission arises from Bi3+ in 6 coordination sites. It is noteworthy that the emission intensity and thermal stability of the phosphors can be further improved by partially substituting Ga3+ with Al3+. By incorporating Y2LaCaGa3ZrO12: 0.02Bi3+ or Y2LaCaGa2.7Al0.3ZrO12: 0.02Bi3+ with commercial phosphors and depositing them onto a 365 nm ultraviolet chip, the prototype white light emitting diodes (w-LEDs) exhibits white light with high CRI of 89.6 and 90.4, respectively. These results validate the potential of Bi3+ activated Y2LaCaGa3-yAlyZrO12 (y = 0–1) cyan phosphor as a promising candidate material for application in UV-excited w-LEDs.

Bright Bifacial White-Light Illumination by Highly Deformable Electroluminescent Devices Based on Transparent Ionic-Hydrogel Electrodes and Quantum-Dot Color Conversion.

Deformable alternating-current electroluminescent (ACEL) devices are of increasing interest because of their potential to drive innovation in soft optoelectronics. Despite the research focus on efficient white ACEL devices, achieving deformable devices with high luminance remains difficult. In this study, this challenge is addressed by fabricating white ACEL devices using color-conversion materials, transparent and durable hydrogel electrodes, and high-k nanoparticles. The incorporation of quantum dots enables the highly efficient generation of red and green light through the color conversion of blue electroluminescence. Although the ionic-hydrogel electrode provides high toughness, excellent light transmittance, and superior conductivity, the luminance of the device is remarkably enhanced by the incorporation of a high-k dielectric, BaTiO3. The fabricated ACEL device uniformly emits very bright white light (489cdm-2) with a high color-rendering index (91) from both the top and bottom. The soft and tough characteristics of the device allow seamless operation in various deformed states, including bending, twisting, and stretching up to 400%, providing a promising platform for applications in a wide array of soft optoelectronics.

MAS:Eu-YAG:Ce composite phosphor converters with excellent thermal performance and enhanced color rendering index for high-power white LDs

Phosphor converters with excellent thermal performance and high color rendering index (CRI) demonstrate vast application prospects in the field of laser diodes (LDs) lighting. Nevertheless, the significant heat accumulation within the converters and the absence of red spectral components pose challenges in achieving both a high saturation threshold and a high CRI for Y3Al5O12:Ce phosphor converters destined for white LDs. In this work, Mg2Al4Si5O18:Eu/Y3Al5O12:Ce (MAS:Eu/YAG:Ce) composite phosphor converters with excellent thermal performance and enhanced CRI were designed and fabricated for reflective laser lighting. Impressively, MAS:Eu/YAG:Ce phosphor-glass-ceramic composites (PGCC) retained a remarkable 97.8 % of the room temperature emission intensity at 150 °C. The reasons for this could be attributed to the strong thermal quenching resistance exhibited by MAS:Eu phosphors, as well as the ultra-thin glass bonding layer of about 150–200 μm. Meanwhile, by integrating the MAS:Eu/YAG:Ce PGCC with a 450 nm laser source, white LD devices operating in a remote excitation mode were fabricated. These white LDs demonstrated an improved CRI of 76 and maintained a low surface temperature of 131.7 °C under an ultra-high laser power density of 47.8 W/mm2 (laser power ∼ 4.70 W). Moreover, the maximum luminous flux and luminous efficiency of the white LDs were 484 lm and 103 lm/W, respectively. Therefore, the design of MAS:Eu/YAG:Ce composite phosphor converters offers a new approach for the development of high-power white LDs.

High‐Performance White Emission from Cu‐Based Perovskite Compound

AbstractThe white emissions based on lead‐free perovskites with broadband emission due to self‐trapped excitons (STEs) are considered as an ideal candidate for next‐generation white light‐emitting diodes (WLEDs). Recently, copper‐based halide perovskites Cs3Cu2I5@CsCu2I3 composites films with a high color‐rendering index (CRI) have been developed for WLEDs. However, the Cs3Cu2I5@CsCu2I3 composites generally exhibit a relatively low photoluminescence quantum yield (PLQY). Herein, a high PLQY up to 86.75% copper‐based perovskite Gua3Cu2I5 (Gua = guanidine) films with a broadband strong yellow STEs emission centered at 544 nm is synthesized. By combining with efficient blue STEs emission Cs3Cu2I5 component via composition engineering of Cs3Cu2I5@Gua3Cu2I5, a high PLQY of up to 96.1% is achieved on the white emission composites films. Moreover, a high CRI of 93 WLEDs is achieved by integrating Cs3Cu2I5@Gua3Cu2I5 composites film onto a UV LED chip. These findings provide a simple and effective strategy for designing highly efficient white light‐emitting diodes.

High quantum efficiency and excellent thermal stability in Eu3+ -activated CaY2ZrGaAl3O12 phosphors for wLEDs

There is a high demand for phosphorescent white light-emitting diodes (wLEDs) that possess low correlated color temperature (CCT) and high color rendering index (CRI), as they are considered to be environmentally friendly sources of solid-state illumination. A novel, UV-excited red light emitting Eu3+-activated CaY2ZrGaAl3O12 phosphor was synthesized for the preparation of warm wLEDs with high CRI and low CCT were obtained. Eu3+-doped CaY2ZrGaAl3O12 phosphors were synthesized with varying concentrations of Eu3+ dopant. The luminescence of Eu3+ was thoroughly examined at its optimal concentration of 20 mol%. Surprisingly, CaY2ZrGaAl3O12: 20%Eu3+ exhibits a broad excitation band of 200–550 nm and some sharp excitation peaks, the highest peak is observed at 251 nm. A dazzling red light, ranging from 550 to 750 nm, is emitted by CaY2ZrGaAl3O12: 20%Eu3+ phosphor. The excitation of ultraviolet light at a wavelength of 251 nm was employed, with an impressive internal quantum efficiency of 90.7% and a remarkable thermal quenching resistance. The wLED was packaged with green phosphor (BaMgAl10O17: Eu2+), red phosphor (CaY2ZrGaAl3O12: Eu3+), blue phosphor ((Ba, Sr)2SiO4: Eu2+) and 395 nm NUV LED chip, which emitted a dazzling warm white light when driven at a current of 20 mA. It has excellent CIE color coordinates (0.3893,0.3736), a low correlation color temperature (CCT) of 3738K, and an excellent color rendering index (Ra = 82.1). The application of the prepared new CaY2ZrGaAl3O12: Eu3+ red phosphor in wLED will promote the development of highly efficient luminous materials for healthy solid-state lighting.

Recent Advances in Preparing Transparent Phosphor Ceramics for High-Index Color Rendering and High-Power Lighting.

In recent years, high-power white light-emitting diode (wLED)/laser diode (wLD) lighting sources based on transparent phosphor ceramic (TPC) materials have attracted increasing application interest in automotive headlights, projection displays, and space navigation lighting due to their superior brightness, lighting distance, compactness, lifespan, and environmental resistance compared with the widely used phosphor-converted wLEDs. However, preparing TPC-converted wLEDs/wLDs with high color rendering index (CRI) remains a huge challenge, which limits their widespread application. In this review, we summarize the recently adopted strategies for constructing TPCs to develop high-power wLEDs/wLDs with high CRI values (>75). The construction protocols were categorized into four groups: host regulation, red-emitter doping, host regulation/red-emitter doping combination, and composite structure design. A comprehensive discussion was conducted on the design principles, photoluminescent properties, and device performances for each strategy. The challenges and future trends of high-power and high-CRI wLEDs/wLDs based on TPCs are also discussed toward the end of this review.

Ce3+-Activated SrLu2Al3ScSiO12 Cyan-Green-Emitting Garnet-Structured Inorganic Phosphor Materials toward Application in Blue-Chip-Based Phosphor-Converted Solid-State White Lighting.

Phosphor-converted white-light-emitting diodes (WLEDs) with superhigh color rendering index (CRI) are the ongoing pursuit of next-generation solid-state lighting. One of the most important challenges is the limited improvement in CRI on account of the absence of a cyan component in the typical commercial combination. Here, a bright broad-band cyan-green-emitting phosphor with cubic garnet structure, SrLu2Al3ScSiO12:Ce3+ (SLASSO:Ce3+), was successfully reported, which can compensate for the absence of cyan cavity in the 480-520 nm blue-green emission region. With 439 nm blue-light irradiation, the as-fabricated SLASSO:Ce3+ phosphor yields a broad-band cyan-green emission with the maximum emission peak positioned at 525 nm and an appropriate full width at half-maximum (fwhm) of 111 nm, capable of providing more cyan emission component without sacrificing green emission. Meanwhile, the optimal SLASSO:2%Ce3+ phosphor features CIE color coordinates of (0.3254, 0.5470) with cyan-green hue, along with a high internal quantum efficiency of up to 93%. Additionally, thermal stability measurements at different temperatures reveal that the luminescence emission intensity of the proposed phosphor retains 44% of its original integral emission intensity at 423 K with respect to room temperature, while also demonstrating an excellent color stability (ΔE = 5.4 × 10-3). This work shows that the highly efficient SLASSO:Ce3+ garnet phosphor can be utilized as a potential cyan-green-emitting phosphor for filling the cyan gap, resulting in the construction of a high-quality warm WLED with high CRI for "human-centric" sunlight-like full-spectrum solid-state illumination.

Tunable cold/warm white light emission from Bi3+/Te4+ co-doped Cs2ZrCl6 perovskite phosphors

Combining a single-component white-light phosphor with ultraviolet light emitting diode chips emerges as a promising method to produce white-light-emitting diodes (WLEDs). Nevertheless, it is still a challenge for synthesizing single-component white-light phosphors with a high color rendering index (CRI). Herein, Bi3+/Te4+ co-doped Cs2ZrCl6 perovskite white-light phosphor is presented with a high CRI of 91.7 and good stability against oxygen, water, and heat. The Cs2ZrCl6 microcrystals were prepared using an ultrasound-assisted hydrochloric acid method with controllable Bi3+ and Te4+ dopant contents. By manipulating the excitation wavelength, the emission light can be altered between cold and warm white. The Bi3+/Te4+ co-doped Cs2ZrCl6 phosphor can also emit the warm-white light, showing a high photoluminescence quantum yield of 82.9%. The presented Bi3+/Te4+ co-doped Cs2ZrCl6 perovskite phosphors with a high CRI and great environmental stability offer a new approach for the synthesis of single-phase white-light phosphors and have high potentiality for the application of WLEDs.

Full-Spectrum White-Light Emission from Triple Self-Trapped Excitons in Hybrid Mixed-Metal Halides.

Low-dimensional metal halides with broadband emissions are expected to serve as downconversion luminescent materials for solid-state lighting (SSL). However, efficiently generating full-spectrum white-light emission with a high color-rendering index (CRI) in single-phase emitters remains a challenge. Here, we report a novel zero-dimensional (0D) hybrid mixed-metal halide (TPA)2CuAgI4 (TPA = tetrapropylammonium), in which individual [CuAgI4]2- dimers are completely isolated and surrounded by the organic cations TPA+. Cu+ and Ag+ share the same crystallographic site in [CuAgI4]2- dimers with the same statistical probability. Upon photoexcitation, single crystals exhibit a full-spectrum white-light emission with a full width at half-maximum (fwhm) of up to 314 nm and a high quantum efficiency of 46.8%. Detailed photophysical studies and theoretical calculations reveal that the ultra-broadband emission of (TPA)2CuAgI4 originates from the radiative recombination of red-, green-, and blue-emitting self-trapped excitons in [CuAgI4]2- dimers. In addition, (TPA)2CuAgI4 nanocrystals were successfully synthesized and exhibited optical properties similar to those of single-crystal counterparts. Finally, a prototype ultraviolet (UV)-pumped white-light-emitting diode (WLED) and a composite thin film employing this new white-light emitter produces a well-distributed full-spectrum white light with a high CRI of 91.4 and a warm correlated color temperature (CCT) of 4135 K, indicating the potential application of this white-light emitter in SSL. These results provide a new perspective for designing superior single-phase white-light emitters.

Color‐Tunable TADF Conjugated Polymers Toward Voltage‐Regulating White OLEDs for Intelligent Lighting

AbstractColor‐tunable luminescent polymers are highly desirable materials for meeting the daily needs of humans in terms of circadian rhythm, yet they are rarely reported. Herein, a feasible approach is developed for color‐tunable thermally activated delayed fluorescence (TADF) conjugated polymers by incorporating green and red TADF units into blue fluorescent polymeric backbone. The solution‐processed OLEDs based on the synthesized polymers exhibit high‐efficiency red emission with a maximum external quantum efficiency (EQEmax) of 26.1% under low voltage (6 V). With a slight increase in voltage, warm white emission with EQEmax of 23.9%, color rendering index (CRI) of 76 and low corelated color temperature (CCT) of 1700 K is obtained. These results represent the highest efficiencies among the red and warm white OLEDs based on TADF polymers, respectively. Intriguingly, under higher voltage (10 V), warm white emission with high CRI of 87, CCT of 3216 K, and luminance of over 5300 cd m−2 is accessible. This work provides a promising approach for intelligent lighting by voltage‐regulating white OLEDs.

The effects of light emitting diodes on mitochondrial function and cellular viability of M-1 cell and mouse CD1 brain cortex neurons.

The invention of Light Emitting Diode (LED) revolutionized energy-efficient illumination, but concerns persist regarding the potential harm of blue light to our eyes. In this study, we scrutinized the impact of LED light characteristics on eyes using two cell types: M-1 (rich in mitochondria) and CD-1 (neuronal). Variations in color rendering index (CRI) and correlated color temperature (CCT) were investigated, alongside exposure durations ranging from 0 to 24 hours. The findings illuminated the potential benefits of high-quality LED lighting, characterized by a high CRI and low CCT, which emits a greater proportion of red light. This form of lighting was associated with enhanced cell proliferation, elevated ATP levels, and reduced oxidative stress. In contrast, LEDs with low CRI and high CCT exhibited adverse effects, diminishing cell viability and increasing oxidative stress. These results suggest that high-quality LED lighting may have neuroprotective potential as a treatment option, such as for retinal ganglion cells.

Ultra-broadband emission up to 181 nm of VO4-activated yellow phosphor for white light-emitting diodes with high color rendering index

Exploring broadband yellow phosphors capable of covering the cyan to red region is an effective approach to achieve high-performance phosphor-converted white light-emitting diodes (pc-WLEDs). Herein, we synthesized a series of VO4-activated ultra-broadband KSrP1−xVxO4 (0.1 ≤ x ≤ 1) yellow phosphors via high temperature solid-state reaction. Successive substitution of P5+ with V5+ causes a slight expansion of the lattice constant and induces several highly localized energy-levels within the forbidden band. Density functional theory calculations confirm that these newly appeared sharp-line energy-levels are attributed to the constructed VO4 anionic groups. With the optimized V5+ content, the KSrP0.7V0.3O4 phosphor exhibits an ultra-broadband yellow emission centered at 537 nm under 355 nm excitation. Impressively, its full width at half maximum is up to 181 nm, exceeding that of most reported counterparts. At 105 °C, the KSrP0.7V0.3O4 sample experiences an emission loss of 53%. A WLED device is fabricated by using phosphor blend of KSrP0.7V0.3O4 yellow phosphor and the commercial BaMgAl10O17: Eu2+ blue phosphor and a 355 nm NUV LED chip, demonstrating bright white emission with high color rendering index (CRI) of 90 and suitable correlated color temperature of 5953 K. These findings indicate that this phosphor has great potential for achieving high CRI WLEDs.

Dual emission quaternary alloyed quantum dots for white light-emitting diodes with high color-rendering index

We report the synthesis of manganese doped Ag–Zn–In–S(AZIS)/ZnS QDs for the facile fabrication of white light-emitting diodes (WLEDs). By controlling the ratio of Mn/(Zn + In), dual emission Mn:AZIS/ZnS QDs with different relative proportion of host emission and Mn2+-related emission were prepared. With proper doping, the emission of Mn: AZIS/ZnS QDs covers most of the visible spectrum. Based on the as prepared Mn:AZIS/ZnS QDs, a warm WLED device exhibited a highest color rendering index (CRI) of 92.5 companied by a correlated color temperature (CCT) of 3162 K. With the increasing of Mn2+ concentration, the corresponding WLED devices shown warmer CCT values and lower luminous efficiencies (LEs). The color-conversion efficiency of the QDs decreasing with the increasing of Mn2+ concentration may be responsible partly for the variation of device LEs. With further deep investigation on the mechanism of color-conversion between the exciting light and QDs, and the energy transfer from the host material to the manganese dopant, WLEDs based on the dual emission Mn:AZIS/ZnS QDs with better device performances are excepted to find diverse application in lighting fields.