Diode Chips Research Articles

Lead‐free Halide Perovskites With ≈100% PLQY and Dual‐Color Emission for White Light‐Emitting Diodes

AbstractLead‐free halide perovskites (LHP) have attracted extensive attention in the field of next‐generation solid‐state lighting. However, single perovskite phosphor with tunable white‐light emission and ultra‐high photoluminescence quantum yield (PLQY) are rare. Here, the tunable dual‐color emission LHP phosphor is developed with a near‐unity PLQY of 99.5%. The LHP phosphor comprises Cs2NaInCl6: Sb3+/Bi3+ and Cs2InCl5·H2O: Sb3+/Bi3+ crystals, with the transition between these two perovskite structures being adjustable by the concentration of Na+. The addition of NaCl inhibits the hydrolysis of the [Sb(H2O)Cl5]2− octahedron, resulting in 3D connected [SbCl6]3− octahedron with less Jahn‐Teller distortion, and the PLQY of LHP is greater than 90%. Finally, the white‐light diode device is fabricated by assembling the LHP with a ultraviolet light‐emitting diode chip and the white light‐emitting diode device achieved Commission Internationale de l'Eclairage color coordinates of (0.34, 0.33), correlated color temperature of 4936 K, and a high color rendering index of 92.9. The LHP perovskite exhibited multimodal luminescence when excited by 365, 335, and 310 nm UV light, showing the multi‐mode anti‐counterfeiting capabilities of the LHP crystals.

A novel high-brightness red phosphor Ca4Nb2O9: Eu3+ for WLEDs

In this study, new phosphors Ca4Nb2O9 doped with Europium (Eu3+) ions were created using a high-temperature solid-state method. Characterizations with X-ray diffraction (XRD), Rietveld refinement, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS) and elemental mapping revealed successful doping and uniform elemental distribution. The band gap is 4.17 eV for Ca4Nb2O9 and 3.73 eV for Ca3.7Nb2O9: 0.3Eu3+, which is shown that the band gap decreases with increasing concentration. Subsequently, the samples underwent photoluminescence (PL) spectra testing, revealing that the Ca4Nb2O9: Eu3+ phosphors exhibited intense red emission when excited at 395 and 465 nm. Meanwhile, the principal emission peak resided at 613 nm, and the ideal doping concentration of Eu3+ was determined to be x = 0.3. In addition, at 420 K, the luminous intensity of Ca3.7Nb2O9: 0.3Eu3+ under 395 and 465 nm excitation is 60 % as well as 82 % of its strength at 300 K, respectively, indicating excellent thermal stability. Furthermore, the phosphor exhibits a relatively high quantum efficiency, reaching 45.47 % when excited with 395 nm light and 58.17 % when excited with 465 nm light. Finally, a white light-emitting diode (WLED) device with a Ra value of 86.3 and correlated color temperature (CCT) of 4450 K was fabricated. The results suggest that the prepared phosphor, in combination with a near-ultraviolet (NUV) light-emitting diode (LED) chip, has the potential for application in white light-emitting diodes.

Pressure Visualization and Quantification Photonic Skin Based on Flexible Optical Fiber Combiner

AbstractThe integration of pressure quantification and visualization enhances pressure perception, accuracy, and efficiency. Current solutions require improvements in quantization accuracy, structural simplicity, and integration. We proposed a novel photonic skin comprising a 3 × 1 flexible optical fiber combiner, integrating red, green, and blue light emitting diode (LED) chips through three flexible optical fibers. Under pressure, changes in the optical fibers' transmission loss alter the output light intensity ratio, thus inducing a color shift at the combiner's output. This visible change can be precisely quantified using a color sensor chip. Performance metrics include sensing range up to 33N, sensitivity between 0.04 and 0.24 dB N−1, detection limit below 0.08 N, response time of 500 ms, recovery time of 400 ms, and durability exceeding 2000 cycles. A compact flexible circuit board manages light source driving, data acquisition, and wireless communication, forming a wearable photonic skin system. This system enables visual recognition and quantitative measurement of pressure across diverse scenarios, including different tactile modes, multi‐position pressure, finger bending, and neck movement. For oral occlusion force detection, the spatial separation of the sensing and visualization areas enables the system to simultaneously provide accurate measurements and intuitive visual assessment.

Micro magnetic field sensor based on bifunctional diodes

Multiple-quantum well (MQW) diodes can be used as bifunctional diodes due to the emission-detection spectral overlap. When integrated with magnetic fluids (MFs) that have tunable refractive index, they can be designed as micro magnetic field sensors. The sapphire substrate of the MQW diode chip that consists of an MQW transmitter and receiver that is directly exposed to the MF, and the external magnetic field strength is used to change the refractive index at the boundary between the sapphire and the MF, thus modulating the reflected light and realizing external magnetic field sensing. Verified by experimental measurements, the micromagnetic field sensor has a detection range of 0.001-0.05 T, a sensitivity of 127.3 µA/T, and a resolution of 4.5×10−5 T, with excellent stability and repeatability. Additionally, the sensor demonstrates good velocity resolution under dynamic magnetic fields and can detect the direction of magnetic field motion, providing significant application value.

Improvement of luminescence properties in Zn2.1Mg0.9Ta2O8:Cr3+ by the cation substitution and its application in biological nondestructive testing and night vision lighting.

Recently, it is of great significance to explore near-infrared (NIR) phosphor with more application prospects. In this work, a series of Zn2.1 Mg(0.9 - y)GaySnyTa(2 - y)O8:0.003Cr3+ NIR broadband phosphors with high quantum yields and high thermal stability are discovered by uniquely replacing [Mg2+-Ta5+] in Zn2.1Mg0.9Ta2O8 with [Ga3+-Sn4+]. Under 460 nm excitation, Zn2.1Mg0.85Ga0.05Sn0.05Ta1.95O8: 0.003Cr3+ depicts the 600-1100 nm broadband emission with a full-width at half maximum (FWHM) of 210 nm, and the quantum yields can reach 61.2%. Finally, the phosphor was mixed with epoxy resin and encapsulated in a 460 nm blue light emitting diode (LED) chip to convert the NIR LED by phosphor (NIR pc-LED), which was applied in the field of biological nondestructive testing and night vision lighting.

Eco-friendly synthesis of red-emissive carbon dots for visual alcohol detection and light-emitting diodes

Red-emissive carbon dots (R-CDs) is highly desired in developing full-color solid-state lighting and display applications based on CDs. Developing simple and eco-friendly methods to produce R-CDs is extremely desirable. In this work, two types of R-CDs were obtained via simple and eco-friendly grinding-heating or solvothermal methods using fresh spinach leaves as the carbon source, respectively. The obtained R-CDs naturally possess surface functional groups. These R-CDs were effectively used as sensitive probes for detecting alcohol (including alcohol gas and liquor detection) due to the synergistic effect of the nitrogen-containing surface groups on the R-CDs and the oxhydryl groups in the alcohol solution. Finally, red electroluminescence was achieved by mixing the R-CDs with polyvinyl pyrrolidone as the phosphor layer on a blue light-emitting diode (LED) chip. This work paves the way for the further development of R-CDs in fluorescence probes and full-color LED applications.

Thermal Analysis of THz Schottky Diode Chips with Single and Double-Row Anode Arrangement.

GaN Schottky diodes show great potential in high-power terahertz frequency multipliers. The thermal characteristics of GaN Schottky diodes with single and double-row anode arrangements are described in this paper. The temperature distribution inside the Schottky diode is discussed in detail under the coupling condition of Joule heat and solid heat transfer. The effects of different substrates and substrate geometric parameters on the thermal characteristics of the Schottky diode chips with single and double-row anode arrangements are systematically analyzed. Compared with that of the chip with single-row anode arrangement, the maximum temperature of the chip with double-row anode arrangement can be reduced by 40 K at the same conditions. For chips with different substrates, chips with diamond substrates can withstand greater power dissipation when reaching the same temperature. The simulation results are instructive for the design and optimization of Schottky diodes in the terahertz field.

Multi‐layer graphene nanosheets bridging binary aluminium oxide for the synergistic enhancement of thermal conductivity and electrical insulation of silicone resin composite

AbstractThe flexible polymer composites usually require high intrinsic thermal conductivity fillers for the applications in thermal management, such as the well‐known graphene, which can, in turn, compromise their electrical insulation properties. Here, the authors developed the silicone resin (SR) composites filled with multi‐layer graphene nanosheets (MGN) and binary alumina (Al2O3), and the microstructure of composites exhibits the dominant skeleton of large‐sized Al2O3 filler and branching of small‐sized Al2O3 fillers features by the size matching effect of optimal binary Al2O3. The introduction of supplementary MGN fillers further increases the face‐to‐face contact probability and bridges the isolated binary Al2O3, which contributes to the high thermal conductivity of 3.0 W·m−1·K−1 under these synergistic effects. The dense and connected ‘Al2O3‐MGN‐Al2O3’ thermal conductive pathway is successfully built, as supported by the numerical simulation and Agari model fitting. Meanwhile, the electrical conductivity caused by MGN can be blocked by the surrounding insulation Al2O3 filler network, exhibiting a high volume resistivity of 1.7 × 1015 Ω · cm. Moreover, the Al2O3/MGN/SR composite films effectively transfer the heat and diminish the hot‐spot temperature by 53.5°C in cooling light emitting diode chip module application.

Mn2+–Mn2+ Dimers Induced Robust Light Absorption in Heavy Mn2+ Doped ZnAl2O4 Near‐Infrared Phosphor with an Excellent Photoluminescence Quantum Yield and Thermal Stability

AbstractTransition metal ions, such as Cr3+, Fe3+, and Ni2+, are widely recognized activators for efficient broadband near‐infrared (NIR) phosphors. However, the potential of Mn2+ ions as NIR‐emitting activators is relatively overlooked due to their typically narrowband emission in the visible spectral region and relatively weak absorption. Herein, a heavy Mn2+‐doped Zn1‐xAl2O4: xMn2+ (ZAO: xMn2+) phosphor is presented that exhibits a single NIR emission band peaked at 830 nm with a bandwidth of 135 nm under excitation at 450 nm. Through comprehensive structural and spectral analysis, this NIR band is attributed to the emission originating from Mn2+ ions within the MnO6 octahedra. Importantly, the formation of Mn2+–Mn2+ dimers breaks the spin‐forbidden rule and significantly enhances the transition probability, as supported by the excited state dynamic analysis. Consequently, the optimal ZAO: 0.70Mn2+ sample shows high internal/external photoluminescence quantum yields of 85.8%/36.9%, along with good thermal stability demonstrated by the emission intensity at 423 K retains 60% of that at 298 K. Finally, a prototype NIR pc‐LED device is fabricated by combining ZAO: 0.70Mn2+ phosphor with a 450 nm blue diode chip, generating an NIR output power of 28.84 mW at 100 mA. This study provides novel insights into high‐performance Mn2+‐activated NIR phosphors.

Novel single phase warm white-emitting phosphor BaLaGaO4:Dy3+,Sm3+ with high thermal stability and color stability

In this study, new phosphors BaLaGaO4 (BLGO) doped with dysprosium (Dy3+) and samarium (Sm3+) ions were created using a high-temperature solid-state method. Characterizations with X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and elemental mapping revealed successful doping and uniform elemental distribution. Then the samples were tested for photoluminescence (PL) spectra, the results indicated that the BaLaGaO4:xDy3+ (BLGO:xDy3+) phosphors emitted strong blue and yellow light upon excitation at 350 nm. The emission peaks were located at 480 and 572 nm, respectively. By introducing different proportions of Sm3+ ions, the BaLaGaO4:0.04Dy3+,ySm3+ (BLGO:0.04Dy3+,ySm3+) samples could be excited at 365 nm, and enhancing the red emission component of the phosphor. Meantime, with increasing Sm3+ content, the correlated color temperature (CCT) decreased from 5507 to 3767 K. And the emission spectrum and decay lifetime of BLGO:0.04Dy3+,ySm3+ confirmed the energy transfer from Dy3+ to Sm3+. Furthermore, at 423 K, the luminous intensity of BLGO:0.04Dy3+,0.04Sm3+ retained 86 % of its strength at 298 K, and the chromaticity shift (ΔS) was only 0.00574, which indicated that the sample had excellent thermal stability and excellent color stability. Finally, using the prepared sample and a 365 nm light-emitting diode (LED) chip, a white light-emitting diode (WLED) was fabricated. The CCT of the manufactured WLED also showed a corresponding reduction (from 3423 to 2814 K). Moreover, under the working conditions of 3.4 V and 0.6A, the thermal imaging obtained after 90 min of WLED operation shows the stability of the packaged WLED at high temperature. These researches show that the phosphor has potential application value in indoor lighting technologies.

Green‐Emissive Carbon Dots with a High Quantum Yield Applied for Photoconversion Film to Prevent from Blue Light Damage

AbstractHigh‐energy blue light is highly detrimental to health as it can penetrate the lens into the retina, potentially causing atrophy or even death of retinal pigment epithelial cells. To prevent the harmful effects of high‐energy blue light on our health, here the preparation of a photoconversion film specifically designed to block high‐energy blue light is reported, which is composed of green‐emissive carbon dots (G‐CDs) with a high photoluminescence quantum yield (PLQY = 95%) dispersed in polyvinyl alcohol (PVA) matrix. Notably, such a film (named as G‐CDs@PVA) not only converts an incident laser light with a short wavelength into a fluorescence with a longer wavelength, but also exhibits concentration‐dependent (0, 10, 20, and 30 wt.%) blue light barrier rate and green‐emissive intensity. With the increase of the concentration of G‐CDs in the film, the blue light barrier rate of the film as well as the maximum intensity of the green emission are also increased. When the concentration of G‐CDs reaches 30 wt.%, the blue light barrier rate of G‐CDs@PVA achieves up to 97%. Furthermore, G‐CDs@PVA film is attached to a blue light‐emitting diode (LED) chip to explore its practical application in the field of blocking blue light damage.

Fabrication and bonding of In bumps on Micro-LED with 8 μm pixel pitch

Indium (In) is currently used to fabricate metal bumps on micro-light-emitting diode (Micro-LED) chips due to its excellent physical properties. However, as Micro-LED pixel size and pitch decrease, achieving high-quality In bumps on densely packed Micro-LED chips often presents more challenges. This paper describes the process of fabricating In bumps on micro-LEDs using thermal evaporation, highlighting an issue where In tends to grow laterally within the photoresist pattern, ultimately blocking the pattern and resulting in undersized and poorly dense In bumps on the Micro-LED chip. To address this issue, we conducted numerous experiments to study the height variation of In bumps within a range of photoresist aperture sizes (3 μm −7 μm) under two different resist thickness conditions (3.8 μm and 4.8 μm). The results showed that the resist thickness had a certain effect on the height of In bumps on the Micro-LED chip electrodes. Moreover, we found that, with the photoresist pattern size increasing under constant resist thickness conditions, the height and quality of the bumps significantly improved. Based on this finding, we rationalized the adjustment of the photoresist pattern size within a limited emission platform range to compensate for the height difference of In bumps caused by different resist thicknesses between the cathode and anode regions. Consequently, well-shaped and dense In bumps with a maximum height of up to 4.4 μm were fabricated on 8 μm pitch Micro-LED chips. Afterwards, we bonded the Micro-LED chip with indium bumps to the CMOS chip, and we found that we could successfully control the CMOS chip to drive the Micro-LED chip to display specific characters through the Flexible Printed Circuit (FPC). This work is of significant importance for the fabrication of In bumps on Micro-LED chips with pitches below 10 μm and subsequent bonding processes.

A new yellowish‐green‐emitting phosphor: Eu2+‐doped Ba3YAl2O7.5

AbstractA yellowish‐green emitting phosphor Ba3YAl2O7.5:Eu2+ was synthesized by a solid‐state method. The crystal structure, luminescence, concentration quenching, fluorescence decay, and thermal quenching properties were systematically investigated. Under blue light (440 nm) excitation, Ba3YAl2O7.5:Eu2+ phosphors exhibit a yellowish‐green emission peaking at 550 nm with a full width at half maximum ∼ 69 nm, and The Commission Internationale de l'Eclairage (CIE) coordinates of Ba3YAl2O7.5:Eu2+ are (0.4064, 0.5811). Structural analysis and Van Uitert equation along with fluorescence lifetime analysis reveal that Eu2+ ions occupy 6‐coordinated Y and 9‐coordinated Ba sites in Ba3YAl2O7.5, and therefore generate two emission sub‐bands at 582 and 548 nm. In addition, Ba3YAl2O7.5:Eu2+ phosphor remaining 43% photoluminescence emission intensity at 125°C with an activation energy of 0.372 eV. Utilizing the title phosphor (Ba3YAl2O7.5:3%Eu2+), commercial red (Ca,Sr)AlSiN3:Eu2+ (CSAlSi:Eu2+) phosphor, and InGaN‐based blue light emitting diode (LED) chip, a proof‐of‐concept warm white LEDs (WLEDs) with a color rendering index of 80.1, CIE chromaticity coordinates of (0.411, 0.381), luminous efficacy of ∼ 22.13 lm/W, and correlated color temperature of ∼ 3288 K is achieved. Thus, Eu2+ activated Ba3YAl2O7.5 phosphors have the potential application in WLEDs pumped by a blue LED chip for solid‐state lighting application.

A narrow-band blue emitting phosphor by co-doping Bi3+ and alkali metal ions (Li+, Na+ and K+) with dual luminescence center

The technology of solid-state lighting has developed for decades in various industries. Phosphor, as an element part, determines the application domain of lighting products. For instance, blue and red-emitting phosphors are required in the process of plant supplementing light, arrow-band emitting phosphors are applied to backlight displays, etc. In this work, a Bi3+-activated blue phosphor is obtained in a symmetrical and compact crystal structure of Gd3SbO7 (GSO). Then, the co-doping strategy of alkali metal ions (Li+, Na+, and K+) is used to optimize the performance. The result shows that the photoluminescence intensity is increased by 2.1 times and 1.3 times respectively by introducing Li+ and K+ ions. Not only that, it also achieves narrow-band emitting with the full width of half-maximum (FWHM) reaching 42 nm through Na+ doping, and its excitation peak position also shifts from 322 to 375 nm, which can be well excited by near-ultraviolet (NUV) light emitting diode (LED) chips (365 nm). Meanwhile, the electroluminescence spectrum of GSO:0.6 mol%Bi3+,3 wt%Na+ matches up to 93.39% of the blue part of the absorption spectrum of chlorophyll a. In summary, the Bi3+-activated blue phosphor reported in this work can synchronously meet the requirements of plant light replenishment and field emission displays.

The synthesis and properties of Ca3 Sc2 Si3 O12 :Ce3+ (CSSG) phosphor are utilized for the development of human-centric lighting light-emitting diodes (HCL-LEDs).

In this study, cerium ion (Ce3+ )-doped calcium scandium silicate garnet (Ca3 Sc2 Si3 O12 , abbreviated CSSG) phosphors were successfully synthesized using the sol-gel method. The crystal phase, morphology, and photoluminescence properties of the synthesized phosphors were thoroughly investigated. Under excitation by a blue light-emitting diode (LED) chip (450 nm), the CSSG phosphor displayed a wide emission spectrum spanning from green to yellow. Remarkably, the material exhibited exceptional thermal stability, with an emissivity ratio at 150°C to that at 25°C reaching approximately 85%. Additionally, the material showcased impressive optical performance when tested with a blue LED chip, including a color rendering index (CRI) exceeding 90, an R9 value surpassing 50, and a biological impact ratio (M/P) above 0.6. These noteworthy findings underscore the potential applications of CSSG as a white light-converting phosphor, particularly in the realm of human-centered lighting.

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.

Ti-B-O System for Catalyzing Boron Nitride Nanotube Growth.

Chemical vapor deposition (CVD) stands out as the most promising method for cost-effective production of high-quality boron nitride nanotubes (BNNTs). Catalysts play a crucial role in BNNT synthesis. This work delves into the impact of oxygen (O) on Ti-based catalysts during the CVD growth of BNNTs. In contrast to the B/TiB2 nanoparticles (NPs) and B/TiN NPs systems, the oxygen-containing precursor B/TiO2 NPs remarkably catalyzes the growth of high-quality and high-purity BNNTs across a wider range of synthesis parameters. Subsequent analyses reveal that TiBO3 acts as an active catalyst, facilitating BNNT growth in Ti-based catalyst systems. Moreover, the nanocomposite film synthesized from BNNTs and PVDF-HFP exhibits excellent mechanical properties and heat dissipation capabilities. Utilizing the nanocomposite film as a thermal interface material effectively enhances the heat dissipation for a 5 W light-emitting diode (LED) chip. Consequently, our research confirms the effectiveness of the Ti-B-O system in catalyzing BNNT growth.

Switchable Adhesive Based on Shape Memory Polymer with Micropillars of Different Heights for Laser-Driven Noncontact Transfer Printing.

Switchable adhesive is essential to develop transfer printing, which is an advanced heterogeneous material integration technique for developing electronic systems. Designing a switchable adhesive with strong adhesion strength that can also be easily eliminated to enable noncontact transfer printing still remains a challenge. Here, we report a simple yet robust design of switchable adhesive based on a thermally responsive shape memory polymer with micropillars of different heights. The adhesive takes advantage of the shape-fixing property of shape memory polymer to provide strong adhesion for a reliable pick-up and the various levels of shape recovery of micropillars under laser heating to eliminate the adhesion for robust printing in a noncontact way. Systematic experimental and numerical studies reveal the adhesion switch mechanism and provide insights into the design of switchable adhesives. This switchable adhesive design provides a good solution to develop laser-driven noncontact transfer printing with the capability of eliminating the influence of receivers on the performance of transfer printing. Demonstrations of transfer printing of silicon wafers, microscale Si platelets, and micro light emitting diode (μ-LED) chips onto various challenging nonadhesive receivers (e.g., sandpaper, stainless steel bead, leaf, or glass) to form desired two-dimensional or three-dimensional layouts illustrate its great potential in deterministic assembly.

Thermally-stable and color-tunable novel single phase phosphor Ca2GaTaO6:Dy3+, Sm3+ for indoor lighting applications

This study successfully synthesized novel phosphors Ca2GaTaO6:xDy3+ (CGTO:xDy3+) and Ca2GaTaO6:0.06Dy3+, ySm3+ (CGTO:0.06Dy3+, ySm3+) using the high temperature solid-phase reaction preparation. The microstructure, optical properties, and energy transfer mechanism of the phosphors were studied through X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) spectra and fluorescence lifetimes. XRD and corresponding refinement results indicate that Dy3+ and Sm3+ ions were effectively doped into the Ca2GaTaO6 (CGTO) lattice. The SEM graphs show that the elements in CGTO:0.06Dy3+, 0.5Sm3+ phosphors are uniformly distributed. PL spectra analysis show the CGTO:xDy3+ phosphors display two strong emission peaks located at 482 nm for blue emission and 575 nm for yellow emission when excited with 350 nm light. Under uniform conditions, when excited with 365 nm of light, the CGTO:0.06Dy3+, ySm3+ phosphors emit light that can be tuned with adjustable color coordinates and correlated color temperature (CCT) by incorporating varying proportions of Sm3+ ions. This tunability is achieved through the effective energy migration from Dy3+ to Sm3+ ions within the phosphor material. Furthermore, the emission spectra and weaken lifetimes of the CGTO:0.06Dy3+, ySm3+ confirm the energy transport between Dy3+ and Sm3+, and the energy transfer efficiency reached to 76 %. At 423 K, the luminescence intensity of CGTO:0.06Dy3+, 0.05Sm3+ phosphor retains 87 % of the intensity observed at 298 K, signifying its excellent thermal durability. Finally, the electroluminescent performance of the CGTO:0.06Dy3+ and CGTO:0.06Dy3+, 0.05Sm3+ phosphors packaged on 365 nm light-emitting diode (LED) chips respectively were studied to investigate the capability applications of the phosphors in white light-emitting diodes (WLEDs) field. The CCT of the packaged LEDs decline from 3396 to 2825 K, indicating CGTO:0.06Dy3+, 0.05Sm3+ phosphor shifts to warmer white light. At a voltage input of 3.4 V and a current of 600 mA, the thermal sensing shows that the WLEDs maintain aptitude for 90 min, showing that the packaged WLEDs can function consistently under elevated temperatures. These studies indicated the phosphors have potential applications in indoor lighting.

Sustainable next-generation color converters from P. harmala seed extracts for solid-state lighting.

Traditional solid-state lighting heavily relies on color converters, which often have a significant environmental footprint. As an alternative, natural materials such as plant extracts could be employed if their low quantum yields (QYs) in liquid and solid states were higher. With this motivation, here, we investigate the optical properties of aqueous P. harmala extract, develop efficient color-converting solids through a cost-effective and environmentally friendly method, and integrate them with light-emitting diodes (LEDs). To achieve high-efficiency solid hosts for P. harmala-based fluorophores, we optically and structurally compare two crystalline and two cellulose-based platforms. Structural analyses reveal that sucrose crystals, cellulose-based cotton, and paper platforms enable a relatively homogeneous distribution of fluorophores compared to KCl crystals. Optical characterization demonstrates that the extracted solution and the extract-embedded paper possess QYs of 75.6% and 44.7%, respectively, whereas the QYs of the cotton, sucrose, and KCl crystals remain below 10%. We demonstrated that the paper host with the highest efficiency causes a blueshift in the P. harmala fluorescence, whereas the cotton host induces a redshift. We attribute this to the passivation of nonradiative transitions related to the structure of the hosts. Subsequently, as a proof-of-concept demonstration, we integrate the as-prepared efficient solids of P. harmala for the first time with a light-emitting diode (LED) chip to produce a color-converting LED. The resulting blue-emitting LED achieves a luminous efficiency of 21.9 lm Welect -1 with CIE color coordinates of (0.139, 0.070). These findings mark a significant step toward the utilization of plant-based fluorescent biomolecules in solid-state lighting, offering promising environmentally friendly organic color conversion solutions for future lighting applications.