Gamut Research Articles

Engineering of Molecular Bridge on Buried Interface via Ferrocene Carboxylic Acid for High Performance Perovskite Light‐Emitting Devices

AbstractQuasi‐two‐dimensional (Quasi2D) perovskite materials gained widespread attention due to whose unique and highly desirable luminescence properties. However, the behavior of perovskite lightemitting diodes (PeLEDs) is prejudiced by inefficient cascading energy transfer of perovskite film and unbalanced charges injection. Here, ferrocene carboxylic acid (FcAd) is employed between hole transport layer (HTL) and perovskite layer as a molecular bridge to solve the current problems of PeLEDs. Ferrocene units can bond with [PbBr6]4−, forming one‐dimensional (1D) intermediate phases of FcPbBr3 at the interface, which can manipulate the growth kinetics of perovskite and reconstruct the phase distribution. Therefore, due to the suppression of low dimensional phase content, not only is the cascaded energy transfer of PEA2(CsPbBr3)2PbBr4 films effectively achieved, but also the quasi‐2D perovskite's work function is reduced. Additionally, Pb2+ coordinated with the carboxyl group of FcAd, inducing an electric dipole effect that leads to an further upward shift of the perovskite energy level. Eventually, the synergy achieves a significant tailoring between the perovskite and HTL energy exhibits the most excellent external quantum efficiency (EQE) exceeds 27% and optimal brightness exceeds 240000 cd m−2. Therefore, the preparation method will provide an effective strategy to widen the color gamut of next‐generation displays.

Особливості вивчення колірної гами та колірної тональності зі студентами мистецьких ЗВО

The article is devoted to the actual problem of training specialists in fine and decorative arts, in particular, the study of painting and color science by students of higher primary institutions. The author examines such basic concepts of visual literacy as color gamut, color tonality and the peculiarities of their study by future artists. It was found that the problem of studying the characteristics of color by students of art universities is not sufficiently presented in modern science. However, in teaching painting and color science, it is important to form a holistic perception of color in students, to understand tone, the shape of objects through color, the ability to create color harmonies, mastering the plane of the work, and the ability of students to convey their ideas to the viewer by means of color. It is emphasized that in painting classes, students of art universities get acquainted with the basic concepts of color science – color gamut and color tonality – from the very first classes. Various characteristics of color, common and different in the concepts of “color gamut” and “color tonality” have been studied. Examples of practical tasks are given that contribute to the best possible study of the color gamut and color tonality by future artists. It is emphasized that the color scale and color tonality are one of the main tools for creating an image in artistic works and are used by artists depending on the author's intention. It is emphasized that the variety of color gamuts and tonalities in painting depends on the saturation, lightness, lighting of objects, arrangement of colors in the composition, etc. It was found that solving the issues of color contrast, the harmonious system of color series, the ratio of colors in color gamuts, and color tonality by students of art universities will help in the future in practice to use the acquired knowledge for the high-quality performance of one’s own artistic works.

StainedSweeper: Compact, Variable-Intensity Light-Attenuation Display with Sweeping Tunable Retarders.

Light Attenuation Displays (LADs) are a type of Optical See-Through Head-Mounted Display (OST-HMD) that present images by attenuating incoming light with a pixel-wise polarizing color filter. Although LADs can display images in bright environments, there is a trade-off between the number of Spatial Light Modulators (SLMs) and the color gamut and contrast that can be expressed, making it difficult to achieve both high-fidelity image display and a small form factor. To address this problem, we propose StainedSweeper, a LAD that achieves both the wide color gamut and the variable intensity with a single SLM. Our system synchronously controls a pixel-wise Digital Micromirror Device (DMD) and a nonpixel polarizing color filter to pass light when each pixel is the desired color. By sweeping this control at high speed, the human eye perceives images in a time-multiplexed, integrated manner. To achieve this, we develop the OST-HMD design using a reflective Solc filter as a polarized color filter and a color reproduction algorithm based on the optimization of the time-multiplexing matrix for the selected primary color filters. Our proof-of-concept prototype showed that our single SLM design can produce subtractive images with variable contrast and a wider color gamut than conventional LADs.

Donor-modified asymmetric N/B/O multi-resonance TADF emitters for high-performance deep-blue OLEDs with the BT.2020 color gamut

Spiro-acridine modified N/B/O type MR-TADF emitters realized deep blue fluorescence with an EQEmax of 20.5% and CIE (0.147, 0.048), which is state-of-the-art efficiency for N/B/O type deep-blue MR emitters with CIEy approaching the BT.2020 standard.

Dynamic multi-color switching using ultrathin vanadium oxide on aluminum-based asymmetric Fabry–Pérot resonant structure

Vanadium dioxide (VO2) exhibits strong infrared optical switching due to its insulator–metal phase-transition property. However, in the visible wavelengths, its intrinsic optical switching is quite low. Current research explores solutions like multilayering, intricate structural patterning, high thermal budget processes, and costly metals for improved color switching. Nonetheless, the color gamut coverage with these methodologies remains notably limited. This work overcomes these limitations and demonstrates dynamic multi-color switching covering a large color gamut using a simple, unpatterned, ultrathin (∼ λ14, where wavelength λ is taken as 575 nm at the center of the visible spectrum) asymmetric Fabry–Pérot structure of VO2 on aluminum (Al). We use the transfer matrix method to design the VO2/aluminium (Al)/sapphire structure for maximum visible reflectance switching. VO2 films are synthesized using a simple, low thermal budget atmospheric oxidation of vanadium (V). With varying oxidation durations, different colors of the oxidized samples are observed. Consistent and reversible color-switching is observed visibly and in reflectance measurements with the change in temperature from low (RT ∼ 30 °C) to high (HT ∼ 100 °C) or vice versa due to the phase transition property of the VO2 layer in the structure. Compared to the existing studies, this work shows a significant change in chromaticities and covers a large color gamut when plotted on the CIE chromaticity diagram. This work has potential applications in the fields of display, thermochromic structures, and visible camouflage.

Lighting preferences of Iberian sausages for Spanish observers

We report results of a visual experiment performed by 20 adult Spanish observers using calibrated images of 18 samples of sliced Iberian sausages under 15 illuminations, including 8 illuminants proposed by the International Commission on Illumination (CIE) and 7 light sources found in meat sections of supermarkets in Spain and Japan. Visual results from the pair comparison and magnitude estimation psychophysical methods used in our experiment showed a high correlation (Pearson’s linear correlation coefficient r = 0.915). Illumination strongly influenced color preferences of sliced Iberian sausages. For example, using the magnitude estimation method, the average lighting preferences changed about 2.8/10 for the 15 illuminations tested. There were no statistically significant differences between lighting preferences for different kind of sausages. Exploring quality indices of white lights, we found that the correlated color temperature and gamut area index (Color Res. Appl. 33, 192-202, 2008) provided the highest linear correlations with visual preferences in our current experiment. Lights with correlated color temperatures below 3000 K or gamut area indices below 70 were not preferred. The CIE general color rendering and color fidelity indices provided poor predictions of visual preferences in our current experiment.

Do color enhancement algorithms improve the experience of color-deficient people? An empirical study based on smartphones.

Approximately 8% of the global population experiences color-vision deficiency. It is important to note that "color-vision deficiency" is distinct from "color blindness," as used in this article, which refers to the difficulty in distinguishing certain shades of color. This study explores color enhancement algorithms based on the neural mechanisms of color blindness and color deficiency. The algorithms are then applied to smartphones to improve the user experience (UX) of color-enhancing features in different top-selling smartphone brands with different operating systems (OS). A color-enhancing application program was developed for individuals with color-vision deficiency and compared to two other mature color-enhancing programs found in top-selling smartphones with different mainstream operating systems. The study included both objective and subjective evaluations. The research materials covered three aspects: daily life, information visualization, and videos. Additionally, this research study examines various levels of color enhancement through three dimensions of subjective evaluation: color contrast, color naturalness, and color preference. The results indicate that all color-enhancing features are beneficial for individuals with color-vision deficiencies due to their strong color contrast. The users' color preference is closely linked to color naturalness. The application program preserves the naturalness of colors better than the other two color-enhancing features. The subjective evaluations show similar trends across different operating systems, with differences arising from the use of different color-enhancing algorithms. Therefore, different algorithms may result in different sizes of the color gamut.

High-performance Au@CsPbBrI2 glass for wide color gamut backlit display

Perovskite quantum dots materials have achieved significant progress in the field of optoelectronics owing to their unique advantages, such as a wide color gamut, adjustable wavelength, and low cost. These advantages make them an ideal substitute for CdSe quantum dots in backlit display devices. As a kind of nanoparticles with a localized surface plasmon resonance effect, Au can be effectively used to enhance the photoluminescence of perovskite nanocrystals (NCs). In this study, Au nanoparticles were introduced into a borosilicate glass system with CsPbBrI2 NCs to improve the optical properties. A series of Au@CsPbBrI2 NCs glasses with tunable wavelengths in the range of 628–640 nm was successfully prepared. The photoluminescence quantum yield (PLQY) of the CsPbBrI2 NCs glass was increased from 15% to 68% with the addition of AuBr3. The Au@CsPbBrI2 NC glass showed good aqueous, thermal, and blue light stabilities. Additionally, a backlight conversion film prepared by compounding the Au@CsPbBrI2 NC glass powder exhibiting the optimal properties with polymethylmethacrylate (PMMA), was applied to a liquid crystal display (LCD). The presented image were more saturated and richer. Our results show that the optimized sample has immense potential for practical applications in the field of backlit displays.

Deep-blue narrow-band emissive cesium europium bromide perovskite nanocrystals with record high emission efficiency for wide-color-gamut backlight displays.

Lead halide perovskite nanocrystals (NCs) are highly promising for backlighting display applications due to their high photoluminescence quantum yields (PLQYs) and wide color gamut values. However, the practical applications of blue emitters are limited due to the toxicity of lead, unstable structure, and unsatisfactory PLQY. Herein, we report the successful synthesis of divalent europium-based perovskite CsEuBr3 NCs using a modified hot injection method. By optimizing the reaction conditions, the CsEuBr3 NCs display a deep-blue emission at 443 nm with a full width at half maximum (FWHM) of 28.5 nm, a color purity of 99.61%, and a record high PLQY of 93.51% for deep-blue narrow-band emissive lead-free perovskite NCs as far as we know. The emission mechanism of CsEuBr3 NCs is proved through first-principles calculations and spectral analysis. Notably, the CsEuBr3 NCs exhibit remarkable stability when exposed to high temperature, UV irradiation, and long-term sealed storage. The incorporation of CsEuBr3 NCs into polydimethylsiloxane (PDMS) serving as a converter is utilized for white light-emitting devices (WLEDs). WLEDs for backlight displays achieves a wide color gamut of 127.1% of the National Television System Committee standard (NTSC), 94.9% coverage of the ITU-R Recommendation BT.2020 (Rec.2020), and their half-lifetime is up to 1677 h, providing a promising pathway for highly efficient, environment-friendly and practical liquid crystal display backlights.

Environmental tests and reliability characterization of pixel-sized colloidal QDs for next-generation display technologies

This study investigates integrating pixelated colloidal quantum dot (QD) layers into LCDs to enhance color conversion and pixel-level enrichment for future display technologies. We developed miniature prototypes with pixel-sized QD color-converter layers seamlessly integrated into the backlight unit (BLU). The prototypes, featuring red- and green-emitting QD pixels with a single blue LED on glass substrates, underwent rigorous environmental tests such as Thermal Shock Test (TST), Thermal Cycle Test (TCT), High Temperature High Humidity Test (HHT), and Low Temperature Test (LTT). The assessment covered the uniformity of light, spectral radiance, and CIE color coordinates, revealing insights into the performance of the QD layers through the analysis of pre- and post-environmental tests. Despite a decrease in luminance, the QD layers exhibited resilience against rapid temperature variations, enduring thermal shock, and thermal cycle tests without cracking. However, high-temperature and high-humidity conditions revealed susceptibility. Low-temperature stress tests demonstrated stable color gamut coordinates with no discernible shifts. This research fills a notable gap in the existing literature by conducting comprehensive environmental tests on pixel-sized QD utilization in display technologies, providing valuable insights to enhance the stability, durability, and reliability of QD displays.

КВАНТОВЫЕ ТОЧКИ ДЛЯ СОЗДАНИЯ ВЫСОКОЭФФЕКТИВНЫХ СВЕТОДИОДОВ: ПЕРСПЕКТИВЫ И ВЫЗОВЫ

Quantum dots (QDs) are a promising material for creating highly efficient light-emitting diodes (LEDs) due to their unique optical and electronic properties. QDs allow achieving high quantum efficiency, narrow emission bandwidth, and precise tuning of the color characteristics of LEDs. This arti-cle reviews the main advantages of using quantum dots in LEDs, such as a wide color gamut and high color fidelity, and discusses key technological challenges, including stability, integration with traditional semiconductor materials, and toxicity of some elements. The prospects for the development and applica-tion of QD LEDs in various industries, including display technology, lighting, and solar cells, are analyzed.

Highly stable CsPbBr3/ PMA perovskite nanocrystals for improved optical performance

In this study, to address the stability issues, we synthesized a CsPbBr3-coated poly (maleic anhydride-alt-1-octadecene) (CsPbBr3/PMA) using a modified hot-injection method. The CsPbBr3/PMA perovskite nanocrystals (PNCs) exhibited effective green emission at 522 nm with an improved photoluminescence quantum yield (86.8 %) compared to traditional CsPbBr3 PNCs (54.2 %). The ligands in the polymer coating can bond with the uncoordinated Pb and Br ions on the surface of PNCs to minimize surface defects and avoid exposure to the external environment, enhancing the stability of the perovskites. Time-resolved photoluminescence spectra showed longer lifetimes for CsPbBr3/PMA PNCs, while transient absorption measurements provided valuable insights into the intraband hot-exciton relaxation and recombination. We demonstrate the potential application of CSPbBr3/PMA in a down-conversion white-light-emitting diode (LED) by coupling green CsPbBr3/PMA and red K2SiF6:Mn4+ phosphor-coated glass slides onto a 455-nm blue GaN LED. The white LED produced a white light with the International Commission on Illumination color coordinates of (0.323, 0.345), luminous efficiency of 58.4 lm/W, and color rendering index of 83.2. The fabricated, white-LED system obtained a wide color gamut of 125.3 % of the National Television Standards Committee and 98.9 % of Rec. 2020. The findings demonstrate that CsPbBr3/PMA can be an efficient down-conversion material for white LEDs and backlighting.

Highly efficient and stable Cs3Mn0.93Zn0.07Br5@SiO2 for wide color gamut backlight displays.

Mn-based perovskites have become a new candidate material for backlight display applications. However, low efficiency and poor stability are the key problems limiting the application of Mn-based perovskites. In this work, Zn-doped and SiO2-encapsulated Cs3MnBr5, denoted as Cs3Mn0.93Zn0.07Br5@SiO2 (CMZBS), was successfully synthesized to improve the photoluminescence quantum yield (PLQY) and stability. After Zn doping, the PLQY increased from 51% to 72% due to the reduction in the energy transfer between [MnBr4]2-. The PLQY can be further improved to 80% after coating SiO2. Compared with Cs3MnBr5 (CMB), CMZBS showed better stability against thermal, air, light, and polar solvents (ethanol and isopropanol). In addition, a white LED (WLED) device with a CIE of (0.323, 0.325) was fabricated by integrating CMZBS and the red phosphor K2SiF6:Mn4+ on a 465 nm blue GaN chip, which exhibited a high luminous efficiency of 92 lm W-1 and excellent stability, demonstrating its great potential application in wide color gamut displays.

Deep learning-assisted inverse design of metasurfaces for active color image tuning.

Metasurfaces, artificial planar nanostructures, offer numerous advantages for color printing applications, including ultra-high resolution, resistance to fading, wide color gamut coverage, and multifunctional capabilities. Due to the sensitivity of their resonance spectra to the external environment, metasurfaces have garnered significant interest for color tuning applications. However, most existing approaches are limited to passive color tuning, wherein only the color changes passively while the composite color image remains unaltered. Active color image tuning, on the other hand, requires precise matching of both color and intensity to the designed targets before and after the tuning process. In this study, we propose a novel approach for active metasurface color image tuning by modulating the environmental refractive index. Building upon a forward neural network that establishes the relationship between the metasurface geometric parameters and color/intensity information, we employ a multi-objective inverse adjoint neural network. This network not only overcomes the inherent 'one-to-many' problem in inverse design using neural networks but also facilitates active color image tuning under three distinct environmental conditions. Our work provides a new approach for the inverse design of metasurfaces and opens up possibilities for applications in dynamic color printing, information encryption, and other related fields.

Broadly tunable filter based on a graphene MEMS-photonic crystal composite structure and its application in single-pixel full-color displays

A graphene MEMS tunable narrowband filter with minimal deformation (<2 pm), high voltage sensitivity (>400 nm V−1), high tunable bandwidth (>200 nm) was proposed, achieving full-color display within a single pixel, color gamut reaching 214% of sRGB.

Ca2+-doping for stable pure red CsPbI3 quantum dot light-emitting diodes

Ca2+-doped CsPbI3 QDs satisfy the requirements for wide color gamut as well as the Rec. 2020 exhibiting improved stability under harsh conditions, and their LEDs exhibit a 1.67-fold enhancement in T50 and 1.31-fold enhancement in EQE.

Waste-free life cycle of iron oxide catalysts for dehydrogenation of olefins and alkylaromatic hydrocarbons

For the processes of obtaining isoprene, styrene, divinylbenzene by dehydrogenation methods, iron oxide catalysts are used, the synthesis method of which is close to a waste-free technology. Waste is catalyst dust and chips formed during the screening stage of commercial products, flue gases formed during the activation of the catalyst. In the article, the authors consider the problems associated with waste in the production and operation of iron oxide catalysts for the dehydrogenation of olefins and alkylaromatic hydrocarbons. A method is proposed for the use of catalyst dust formed at the stage of catalyst preparation and utilization of spent iron oxide catalyst for the dehydrogenation of olefins and alkylaromatic hydrocarbons. The possibility of utilization of an ironcontaining spent catalyst for the production of iron oxide pigment and its further use in the production of building materials is shown. A number of decorative concrete samples have been prepared to study the effect of pigment as an additive on the properties of the building material. The dependence of the color gamut of the samples on the amount of pigment applied was studied, strength characteristics were studied in accordance with the regulatory requirements for strength, heat resistance and frost resistance.

Direct synthesis of CsPbX3 perovskite nanocrystal assemblies.

Inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (NCs) possess many advantageous optoelectronic properties, making them an attractive candidate for light emitting diodes, lasers, or photodetector applications. Such perovskite NCs can form extended assemblies that further modify their bandgap and emission wavelength. In this article, a facile direct synthesis of CsPbX3 NC assemblies that are 1 μm in size and are composed of 10 nm-sized NC building blocks is reported. The direct synthesis of these assemblies with a conventional hot-injection method of the NCs is achieved through the judicious selection of the solvent, ligands, and reaction stoichiometry. Only under selective reaction conditions where the surface ligand environment is tuned to enhance the hydrophobic interactions between ligand chains of neighbouring NCs is self-assembly achieved. These assemblies possess narrow and red-shifted photoluminescence compared to their isolated NC counterparts, which further expands the colour gamut that can be rendered from inorganic perovskites. This is demonstrated through simple down-converting light emitters.

The Pitfalls of Wide Color Gamut Displays

AbstractIn this issue, we focus on metrology and human‐factor topics related to displays with narrow spectral power distributions. Although their wide color gamut (WCG) is an attractive attribute, traditional metrics do not necessarily work for WCG displays.

Enhanced stability of CsPbBr3 nanocrystals through Al2O3 and polymer coating.

Lead halide perovskite nanocrystals have emerged as a promising candidate for next-generation display applications due to their attractive optical properties and low-cost production. However, the environmental stability of perovskite remains a major challenge, hindering their practical applications and scalability for commercialization. In this study, we present an effective method to enhance the stability of CsPbBr3 nanocrystals by coating them with a combination of Al2O3 and a polymer. The unique double protection structure significantly improves their resistance to moisture, heat, and polar solvents. It is worth noting that compared with the ordinary CsPbBr3 nanocrystals, the modified nanocrystals have better stability and higher luminous intensity. After soaking in water for 360 hours, the modified nanocrystals retained 85% of their initial luminous intensity. Under optimal conditions, the luminous intensity of modified nanocrystals increased by 36%. Furthermore, the thermal stability and organic solvent resistance of the nanocrystals are improved compared with the nanocrystals uncoated with Al2O3. The synthesized white light emitting diode using the modified PNCs achieves a color gamut coverage rate of 129% under standard NTSC, and 95% under standard Rec.2020, indicating its potential for future display applications. This research presents a promising approach for the development of stable perovskite nanocrystals with enhanced performance in various optoelectronic devices.