Color Conversion Research Articles

Full-Color Gamut White Light Emission From Mn-doped Cs3Cu2X5 Nanocrystals via Lattice Engineering.

Cs3Cu2X5-based lead-free material (X = Cl, Br, and I) nanocrystals (NCs) are promising eco-friendly materials for various optoelectronic applications. Although manganese (Mn2+) ion doping into Cs3Cu2X5 may widen the emission color gamut, incorporating them is challenging because of the robust tetrahedral [CuX4] and triangular [CuX3] structures. This paper addresses this challenge using a lattice engineering strategy, which induces appropriate lattice shrinkage by replacing I- with Cl- in the Cs3Cu2I5 NC structure. The promotion effect of Cl- substitution on the Mn2+ doping is confirmed by structural and chemical analysis, indicating the formation of highly crystalline NCs. The Mn-doping modifies the electronic structures of Cs3Cu2X5 by reducing the band gap energy and forming effective energy transition pathways. The emission range of the NCs is expanded from blue to orange and finally manifest full-color gamut white light emission. The continuous broad spectrum is attributed to the combined blue emission of self-trapped excitons and the yellow-orange emission of the Mn2+ d-d energy transition. A white light-emitting diode with Mn-doped Cs3Cu2X5 NCs as a color conversion layer exhibit stable white emission with CIE coordinates of (0.34, 0.32) and a correlated color temperature of 5010 K, closely matching daylight conditions and is applied as an intelligent artificial sunlight.

Coplanar Pattern and Temperature Transient Control in Intelligent Wearable Multi‐Color Alternating Current Electroluminescence Devices

AbstractFlexible alternating current electroluminescence (ACEL) devices integrated into textiles are gaining significant attention for their potential in lighting displays and health monitoring applications. Traditional challenges include high‐voltage “breakdown” and limited color output due to the inherent properties of ZnS:Cu. This study introduces a novel multi‐color ACEL device featuring a fluorescent dye color conversion layer alongside a robust protective layer designed to enhance device stability. The optimal ratio of dielectric layer concentration and protective layer thickness is systematically investigated to mitigate the risk of “breakdown”. Utilizing the principles of photoluminescence and electroluminescence, luminous electronic textile devices is successfully developed that exhibit both purple and green luminescence. Additionally, integration with a temperature sensor enables the device to serve as a health‐monitoring tool by signaling changes in body temperature. This research delineates the protective capabilities of the protective layer and the efficacy of the color conversion mechanism in maintaining consistent brightness under various conditions. The findings suggest a viable pathway for broadening applications and potentially accelerating the commercialization of wearable electroluminescent technologies.

White light-emitting electrochemical cells based on metal-free TADF emitters

The attainment of white emission from a light-emitting electrochemical cell (LEC) is important, since it enables illumination and facile color conversion from devices that can be cost-efficient and sustainable. However, a drawback with current white LECs is that they either employ non-sustainable metals as an emitter constituent or are intrinsically efficiency limited by that the emitter only converts singlet excitons to photons. Organic compounds that emit by thermally activated delayed fluorescence (TADF) can address these issues since they can harvest all excitons for light emission while being metal free. Here, we report on the first white LEC based on solely metal-free TADF emitters, as accomplished through careful tuning of the energy-transfer processes and the electrochemically formed doping structure in the single-layer active material. The designed TADF-LEC emits angle-invariant white light (color rendering index = 88) with an external quantum efficiency of 2.1 % at a luminance of 350 cd/m2.

Polarization‐Sensitive Subwavelength Nanopixel for On‐Off and Color Switchable Color Printing

AbstractThis study presents a polarization‐sensitive dual nanodisk nanopixel that implements controllable color conversion and on‐off switching. The color, the nanopixel expresses is manipulated by the morphology and the interdisk dielectric gap for adjusting plasmonic coupling tuned by the polarization direction. The method attempted in this way allows for precise adjustment of the peak position, peak shifting range, and intensity depending on the polarization angle, thereby controlling saturation, brightness, and hue. This allows for adjusting the peak shifting range to a tens to hundreds nanometer wavelength range in color conversion mode, and the contrast of light intensity in on‐off mode is realized ≈3.2‐fold higher at 650 nm‐wavelength. Using these nanopixels, are generated image patterns that varied depending on polarization. The proposed nanopixels have the potential for promising future technologies, including displays, optical devices, high‐sensitivity optical sensors, data security and encryption, and data storage.

Elevating Red Emission: Yb3+ Doped CsPbBr1I2 Nanocrystal Glass for Exceptional PLQY and Stability in Wide Color Gamut Backlit Displays

As display technologies progress towards enhanced visual performance, there was a growing demand for color conversion materials to meet increasingly stringent performance requirements. In recent years, all-inorganic perovskite CsPbX3 (X = Cl, Br, I) nanocrystals (NCs) had gained attention in the field of wide color gamut backlight displays due to their tunable full spectrum, narrow-band emission, high color purity, and ease of processing. However, red-emitting perovskite NCs were still facing challenges with photoluminescence quantum yield (PLQY) and stability. In this study, Yb3+ doped CsPbBr1I2 perovskite nanocrystal glass (Yb3+@CsPbBr1I2 PNG) was synthesized using a melt-quenching technique. Samples emitting at a narrow band centered at 630nm, with a full width at half maximum(FWHM) of 31.8nm, exhibited a high PLQY of 80.36% and retained fluorescence intensity at 98.2% of the initial value in water, maintaining to 92.6% after continuous blue light irradiation for 60 days. Moreover, the optical conversion film Yb3+@CsPbBr1I2@CsPbBr3@PET developed in our study showcased color gamut coverage surpassing 132.9% of the NTSC 1953 standard and 98.8% of the Rec.2020 standard. In summary, the highly efficient and remarkably stable red-emitting Yb3+@CsPbBr1I2 PNG composite material introduced in this study paved the way for future advancements in wide color gamut and ultra-high definition backlight display technologies.

Ultra-Narrowband Green-Emitting Transparent Composite Ceramics for Laser-Driven Display.

Laser-driven projection displays face a critical challenge in developing laser-excitable and high-performance narrowband green emitters. Herein, new Al2O3-LaMgAl11O19: Mn2+ (Al2O3-LMA: Mn2+) transparent composite ceramics are reported via high-temperature vacuum sintering, which produces a high-color-purity (95.4%) green emission with full width at half maximum of 24nm and superior thermal and moisture and laser irradiation stability. These are attributed to low electron-phonon couple, weak crystal-field effect, an individual lattice location of Mn2+ activators in high structural rigid host, and the incorporation of a high-thermal-conductivity Al2O3 secondary phase. As a result, the composite ceramics are demonstrated as an attractive color converter with a high external quantum efficiency (38%) and absorption coefficient (53%), which ensures a luminous flux of 2012lm @40.0W, a luminous efficacy of 67.7lmW-1, and a green light conversion efficiency of 20.3% upon blue laser irradiation. This enables to construct a brand-new laser-driven prototype display with a record color gamut beyond Rec.2020 standard (100.8%), outperforming commercial YAG: Ce3+ and β-SiAlON: Eu2+. This exploration in ultra-narrowband green luminescent materials is poised to accelerate the development of "ideal displays" for laser-driven projection display technology.

The First Decade of Colloidal Lead Halide Perovskite Quantum Dots (in our Laboratory).

Ten years after the discovery of colloidal lead halide perovskite nanocrystals (LHP NCs), the field has witnessed substantial progress in synthetic methods, understanding of their surface chemistry and unique optical properties, precise control over NC size, shape, and composition. Ligand engineering, particularly with cationic and zwitterionic head groups, massively enhanced NC stability, compatibility with organic solvents, and photoluminescence efficiency. These breakthroughs allowed for the self-assembly of monodisperse NCs into complex long-range ordered superlattices and enabled the exploration of collective optical phenomena, such as superfluorescence. The development of low-cost scalable approaches like microfluidic systems and mechanochemical synthesis paved the way for the commercialization of LHP NCs, particularly for the down-conversion films in blue-backlit LCDs and as thermally-efficient color converters in pixelated displays. This review aims to trace the journey of these advancements, focusing on contributions from Switzerland, and outline future directions in this rapidly evolving field, such as quantum light sources, photocatalysis, etc.

Development of a Dual-Readout Multicolor Immunoassay for the Rapid Analysis of Isocarbophos in Vegetable and Fruit Samples.

Multicolor immunoassay is a powerful tool for rapid analysis without the use of bulky instruments owing to various color conversions, which is suitable for on-site visual analysis for pesticides. Herein, this study developed a multicolor immunoassay for the rapid detection of isocarbophos. After competitive immunoassay, the secondary antibody (GAM-ALP) catalyzed ascorbyl-2-phosphate (AAP) into ascorbic acid (AA). The AA can reduce K3[Fe(CN)6] into K4[Fe(CN)6]. The latter can react with Fe3+ to form Prussian blue; otherwise, the orange AAP-Fe3+ complex was generated. Therefore, the multicolor immunoassay achieved a color conversion of orange-green-blue in response to isocarbophos, allowing for rapid semiquantitative analysis by the naked eye. After parameter optimization, the multicolor immunoassay was developed depending on the ratiometric absorbance between the Prussian blue and AAP-Fe3+ complex. Moreover, a smartphone was used to measure the RGB value of the color conversion for the development of portable visual, quantitative analysis. Both the absorbance-based and RGB-based multicolor immunoassays showed good accuracy and practicability in the recovery test. This study provided a common approach for the development of dual-readout multicolor immunoassay, which can be used for on-site rapid screening by quantitative or visual semiquantitative analysis.

Lattice‐Matched BaClF/CsPbBr3 Heterostructure with Enhanced and Stable Cyan Emission to Overcome Blue Overshoot and Cyan Gap of White Light‐Emitting Diodes

AbstractCombining blue‐emitting LED chip and yellow‐emitting phosphor coating is efficient in manufacturing white light‐emitting diode (WLED). However, the lack of a uniformly distributed continuous emission spectrum in conventional WLED can result in “blue overshoot” and “cyan gap”, thus cause retinal damage and low color rendering index (CRI). Herein, a novel “kill two birds with one stone” strategy is reported: by preparing BaClF/CsPbBr3 heterostructures via a lattice‐ matching approach, F and Cl in BaClF matrix passivate the bromine vacancies of CsPbBr3 NCs, enhancing luminescence stability and achieving a blue‐shift of PL to obtain cyan‐emission. BaClF/CsPbBr3 heterostructures with controllable emissions in 468–510 nm can be fabricated by adjusting the molar ratios of CsPbBr3 to BaClF, and the photoluminescent quantum yield (PLQY) is up to 80.6%. The cyan‐emitting BaClF/CsPbBr3 heterostructure acting as a cyan color converter can effectively absorb the “blue overshoot” and fill the “cyan gap” in WLED, thus significantly increasing the CRI value of WLED from 70.1 to 86.2 and the luminescent efficiency boosts from 21.3 to 87.8 lmW−1. This work highlights a lattice‐matching strategy to produce ultra‐stable cyan‐emitting perovskite nanomaterials with high brightness and durability, paving the way for the application of perovskite NCs in next‐generation WLED lighting.

Small-Scale Aqueous Suspension Preparation using Dual Centrifugation: The Effect of Process Parameters on the Sizes of Drug Particles

The dual centrifugation approach has in the recent years emerged as a powerful milling tool to prepare pharmaceutical suspensions in submicron range with a fast-milling capacity by milling 40 samples simultaneously in 2 mL vials. While there is some standardized milling conditions described in the literature when preparing aqueous suspensions with dual centrifugation, a more systematic and experimental understanding of the milling process to evaluate the impact of different process variables in the dual centrifuge on the final sizes of the suspended drug particles independent of the drug compound used. Overall, the present study demonstrated the applicability of the dual centrifuge for small-scale screening purposes and showed the impact of process parameters on the physical attributes of prepared suspensions. In the present work, the rate of size reduction on three different model compounds, i.e., cinnarizine, haloperidol, and indomethacin, was found to be mostly influenced by the milling speed, size of milling beads, and the bead loading during milling, whereas the rotor temperature did not affect the particle size profiles when stabilized with polysorbate 20 during milling with dual centrifugation. Smaller particle sizes were in general obtained at the highest milling intensity, i.e., 1500 rpm, smallest bead size, i.e., 0.2 mm, and higher bead loadings (42%, 56%, and 83%). The grinding limit of approximately 0.50 µm, 0.70 µm, and 0.35 µm for cinnarizine, haloperidol, and indomethacin, respectively, was achieved relatively fast, i.e., 30 minutes of milling at the specified conditions, compared to when suspensions were milled with larger bead sizes (i.e., 1.0 mm), lower milling intensities (e.g., 1000 rpm), and lower bead loadings (e.g., 14 or 28%). The study further confirmed that a higher milling intensity was necessary during milling of haloperidol suspensions probably due to the compounds predominantly plastic properties. Sizes of indomethacin particles increased with longer milling runs up to 240 minutes and also higher bead loadings of 56% and 83%. These observations were further supported by the color conversion from white to yellow of indomethacin suspensions which indicated generation of small quantities of amorphic material after milling with a high milling intensity. Upscale investigations showed comparable particle size profiles for all three model compounds while milling at 1500 rpm for five minutes.

Transfer-printed multi-stacked quantum dot color conversion layers for white light-emitting diodes

Transfer-printed multi-stacked quantum dot color conversion layers for white light-emitting diodes

Hue-preserving lightness and saturation modification in RGB color space for protanopia and deuteranopia

Colors are not seen in the same way among all people. For example, to dichromats such as protanope and deuteranope, red and green appear similar ochre-like colors. Therefore, it is difficult for dichromats to distinguish such color combinations. The purpose of this study is to propose a color conversion method that produces images that are easy for dichromats to discriminate colors, without significantly changing the impression of the original image for both dichromats and trichromats. The proposed method modifies the lightness of pixels to take into account colors that are difficult for dichromats to discriminate, thus enabling color discrimination. Furthermore, by also modifying the saturation of the pixels, the image quality degradation caused by overemphasis, which occurs when only modifying the lightness, is suppressed. To demonstrate the effectiveness of the proposed method, experiments using various images are conducted. From the resultant images, it can be confirmed that the proposed method achieves the color conversion that serves its purpose. The main results of quantitative evaluation are as follows. (1) In the index evaluating the degree of contrast improvement for colors which are difficult for dichromats to discriminate, the average value of the proposed method is about 0.84, and indicates that the proposed method is comparable to the conventional methods. (2) In the index represented by the ratio of the number of pixels clipped with white or black, the average of the proposed method is 4.38×10−4 and indicates that there are almost no clipped white and black pixels.

Phosphor-in-glass film on transparent diamond: an emerging new-generation color converter for high-brightness laser lighting

Phosphor-in-glass film on transparent diamond: an emerging new-generation color converter for high-brightness laser lighting

Composition of Quantum Dot Color Conversion Layer with ZnS Nanoparticle for Facile Ink Formulation and Uniform Inkjet Printing

Quantum dot (QD) is excellent material for next-generation displays because of their superior optical properties, such as high quantum efficiency, narrow full width at half maximum, high color purity, and photoluminescence quantum yield. QD demonstrated efficient absorption of blue light, coupled with high color-conversion efficiency, fabricated them suitable for use as color-conversion layers (CCLs). However, robustness in pixel patterning uniformity and a printing resolution should be further studied. Light emission via conversion through QD films or converter pixels still need to be improved because the blue light can directly transmit the QD layers, sometimes leading to insufficient energy to excite the QDs. Thus, many studies on QD CCLs have focused on improving the absorption and emission properties of QDs, formulating CCL resins with enhanced color conversion efficiency. Scattering can alter the optical path and incident angle of the emitted light to increase internal reflection so that light emission of the optical film can be enhanced for excitation of photons. Thus, light scattering particles, such as titanium dioxide (TiO2), silicon dioxide (SiO2), zinc oxide (ZnO), and zirconium oxide (ZrO2) were carefully tuned to achieve outstanding properties as QD CCLs, increasing color conversion efficiency.In this work, zinc sulfide (ZnS) light diffusers with hydrophobic properties and various size distribution were synthesized. ZnS and QD were mixed in acrylic resin, isobornyl acrylate, with proper composition of initiator and photocrosslinker. The recipe of mixing was considered for a fabrication of QD CCL ink with optimum viscosity, dispersion stability and uniformity, and printability. For the QD-CCL ink with relatively high viscosity, evaluation of jetting profile and pixel-patterning was conducted with commercial ink cartridge, Sapphire QE-256/30AAA (Fujifilm), combined with the custom-built inkjet printer and high-speed camera. With the scale up to 200ppi QD-CCL pattern, the color spectrum, printability, dispersion, optical properties (evaluation of color-emitting image), and surface uniformity were evaluated. Overall, this work will demonstrates the enhanced light converion behavior of QD-CCL layer fabricated by inkjet-printing process and provide a novel evaluation prorocol of uniformity for QD-CCL layer and color conversion device using blue micro-LED.

Detection of motor nervous disease using deep learning based Duple feature extraction network

Background A motor nervous disease (MND) is a debilitating nervous disease that affects motor neurons that regulates the muscular voluntary movements. The disease gradually destroys parts of the neurological system. Generally, MND develops owing to a grouping of genetic, behavioural, and natural features. Objective However, early detection of MND is challenging and manual identification requires a lot of time. Therefore, automated methods like deep learning structures are needed to detect MND quickly and more accurately than manual classification. In this work, a novel deep learning-based Duple feature extraction network is proposed for identifying MND in its early stages. Methods Initially, the input DTI images are pre-processed utilizing a Gaussian adaptive bilateral filter (GAB) to improve the quality of the image. Then the pre-processed DTI images are fed into the dual feature extraction phase for colour and structural conversion. The Colour Information Feature (CIF) with Local and Global sampling (LOG) is integrated into the LinkNet module to extract colour features. Moreover, the Local Binary Pattern (LBP) with Edge sampling models is integrated into the MobileNet module to extract edge features. Afterward, the extracted colour and texture features of images are flattered and given as the input to a Deep Neural Network for classifying the MND levels. Results From the test results, the proposed Duple feature extraction network has yielded a 99.62% accuracy rate. The proposed DNN improves its F1-score by 1.32%, 2.1%, and 3.18% better than FNN, GNN, and GRU respectively. The proposed Duple-feature extraction network improves overall accuracy by 6.15%, 5.56%, 5.96%, and 6.68% compared to CNN, SVM-RFE, MLP, and Tri-planar CNN respectively. Conclusion The novel deep learning-based Duple feature extraction framework shows promising results in early detection of motor nervous disease, significantly improving accuracy and f1-scores compared to existing models.

Reactive carbon dots/polysiloxane composites cross-linked silicone resin adhesives for stable white LED constructing

Current high-performance commercial white LEDs typically rely on Ce:Y3Al5O12 (Ce:YAG) phosphors and their dispersed encapsulating material. However, Ce:YAG often has large particle sizes and does not react with the encapsulating material, causing stratification and sedimentation. To address this problem, a novel reactive carbon dots/polysiloxane (R-CDs/PS) composite was synthesized through a one-step solvothermal process involving citric acid, urea, 3-aminopropyltriethoxysilane (APTES), and vinyltrimethoxysilane (VTMS). The composite exhibits yellow emission at 528 nm under UV excitation and has a particle size of approximately 150 nm. To improve integration, vinyl adhesive (vinyl AD) and vinyl MDQ resin were designed and synthesized to enhance adhesion and mechanical strength. When dispersed in silicone resin adhesives (SRAs), R-CDs/PS composite forms a stable color conversion layer, avoiding stratification due to its nanoscale size and chemical cross-linking with SRAs. White LEDs can be easily produced by casting R-CDs/PS composites and SRAs onto LED chips, followed by high-temperature curing. These LEDs exhibit desirable optical properties, including CIE coordinates of (0.33, 0.34), a CRI of 82.2, and a CCT of 5355 K, making them suitable for indoor lighting. This study not only introduces a practical approach for fabricating fluorescent and encapsulating materials but also offers a valuable strategy for improving the stability of white LEDs.

Anaplastic thyroid carcinoma: vimentin segregates at the invasive front of tumors in a murine xenograft model.

Anaplastic thyroid carcinoma (ATC) ranks among the most lethal human cancers. Increased migratory and invasive capabilities arecritical in malignancy and areoften secondary to epithelial-mesenchymal transition (EMT). However, it is not clear whether the invasive behavior of ATC is associated with the presence of EMT. In this study, we used a murine xenograft model (4-week-old male BALB/c NU/NU mice) with the human anaplastic cell line, FRO. We adopted an automated, eye-independent method to reconstruct the total/subtotal area of the tumors. To probe EMT, we evaluated the immunostaining of mesenchymal/epithelial markers at the front and center of the tumors. The transplanted cells invariably gave rise to tumor masses that histologically closely replicated patient tumors. The staining with hematoxylin-eosin and immunostaining with cytokeratin 18, an epithelial marker, were similar. However, the immunostaining of cytokeratin 18 versus vimentin, a mesenchymal marker, were strikingly dissimilar, since vimentin showed a staining concentrated at the front, rapidly declining towards the center of the tumor. The overlay, after color conversion, of cytokeratin and vimentin staining showed maximal coincidence at the front, which was rapidly lost towards the center. The results show EMT signs at the front of the ATC, which are probably at the basis of its tremendous invasiveness. Moreover, methodologically, an automated "eye-independent" acquisition of the total/subtotal area of the tumors drove the selection of second, high-magnification, automated field acquisition. Future studies may extend these results along the perspective of a personalized diagnostic procedure.

Pengenalan Gambar Dasar Menggunakan Python dan OpenCV

OpenCV is a widely used library in the field of image processing and computer vision. Combined with Python's flexibility, OpenCV provides an extensive range of functions for efficient image processing, modification, analysis, and visualization. This paper aims to introduce the fundamental concepts of image processing using Python and OpenCV, including image reading, color conversion, edge detection, and image manipulation such as resizing and cropping. Furthermore, this study discusses basic analysis techniques like color distribution histograms and feature detection. By presenting these concepts, the paper aspires to help readers understand the foundations of digital image processing and explore the potential applications of OpenCV in practical fields such as pattern recognition, object detection, and image segmentation.

High-efficiency pure-red perovskite quantum dots glass via Dy modification for high quality backlight display

Perovskite quantum dots (QDs) glass has been considered as high efficiency, high color-purity, and high stability luminescent materials for display application. Herein, high emissive Dy doped CsPb(Br, I)3 (CPBI: Dy) QDs glass has been prepared, and the effects of doping concentration on the crystallization behavior of QDs were discussed carefully. The low and high concentration of Dy doping brings diametrically opposite tuning effects for the emission wavelength. When high Dy doping, DyBO3 nanocrystals were precipitated from the glass along with CPBI QDs. The highest photoluminescence quantum yield of CPBI: Dy QDs glass reached 53.79 %. The LEDs using the CPBI: Dy QDs glass as color converter could express pure-red light of 630 nm peak with a full width at half maximum of only 25.6 nm. What’s more, the color gamut of a white backlight unit based on prepared CPBI: Dy QDs glass film was 125.8 % of National Television System Committee color gamut standard and 94.0 % of Rec.2020, which has great potential in display application.

Highly Enhanced Light Recycling in Quantum Dot Displays by Sidewall Reflectors

AbstractQuantum dot (QD) color conversion‐based displays have emerged as one of the most promising next‐generation devices due to their superior emission properties in terms of color expression. To date, however, existing QD color conversion layer (QD‐CCL) technologies have suffered from low luminance and power efficiency, mainly due to significant light absorption by the bank structure. Here, the color conversion efficiency of QD‐CCL has been significantly enhanced by fabricating a highly reflective metal layer on the side surface of the bank structure. Using a high‐aspect‐ratio silver reflector fabricated through a secondary sputtering lithographic technique involving argon ion bombardment, the fabricated QD‐CCL is combined with a blue organic light‐emitting diode (OLED) serving as a light source. As a result, light recycling from the reflector significantly enhances color conversion efficiency and luminance by up to 4.60‐fold and 4.29‐fold, respectively. Optical simulation reveals that higher pixel resolution provides greater reflection probabilities during extraction. This photomask‐free approach is not only simple but also highly compatible with existing semiconductor fabrication processes, making it a viable commercial alternative for all color‐converting structures that utilize light‐emitting materials with omnidirectional emission characteristics.