Gamut Research Articles

Synthesis of Carbon Dots/PVP Composite for White Light Emitting Diode (WLED) Application.

Carbon dots (CDs) are extensively utilized in biomedicine, optical devices, and sensing due to their low toxicity, excellent optical properties, and ease of synthesis. Nonetheless, there is ongoing discussion over the comprehensive investigation of CDs photoluminescence (PL) process because of their intricate architectures and surface functions. Carbon dots (CDs) and CD/PVP composites were one step synthesized in a hydrothermal process using citric acid and NaOH as precursors. Due to surface defects of CDs after incorporating into Polyvinylpyrrolidone (PVP) both shift in color as well as change in emission is observed. It shows the enhancement of the luminescence property of CDs/PVP and the application of CD/PVP composite in the field of optical emission. Further for practical application, emission of white light emitting diodes (WLEDs) was demonstrated by coating a 370nm UV-LED with CD/PVP composite. The WLED shows significant CRI, good S/P ratio, the color gamut score Rg and color fidelity score Rf which are essential features for a good light source. Our research offers a valuable reference for CD/PVP composites in a facile, low temperature and low-cost hydrothermal process and developing WLED with UV-LED and metal free phosphors.

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.

Multivalent-effect immobilization of reduced-dimensional perovskites for efficient and spectrally stable deep-blue light-emitting diodes.

Despite substantial advances in green and red metal halide perovskite light-emitting diodes (PeLEDs), blue PeLEDs, particularly deep-blue ones (defined as Commission International de l'Eclairage y coordinate (CIEy) less than 0.06) that meet the latest Rec. 2020 colour gamut standard, lag dramatically behind owing to a severe phase segregation-induced electroluminescent spectral shift and low exciton utilization in broadened bandgap perovskite emitters. Here we propose a multivalent immobilization strategy to realize high-efficiency and spectrally stable deep-blue PeLEDs by introducing a polyfluorinated oxygen-containing molecule. Systematic experiments and extensive 5,000 fs ab initio molecular dynamics simulations reveal that a crucial role of the multivalent effect stemming from three kinds of interaction of hydrogen bond (F···H-N), ionic bond (F-Pb) and coordination bond (C=O:Pb) with perovskite is to synergistically stabilize the perovskite phase and enhance exciton radiative recombination. The resultant exciton concentration and exciton recombination rate of the deep-blue perovskite emitter are increased by factors of 1.66 and 1.64, respectively. In this context, our target PeLEDs demonstrate a peak external quantum efficiency of up to 15.36% at a deep-blue emission wavelength of 459 nm and a half-lifetime of 144 min at a constant current density of 0.45 mA cm-2. Moreover, the deep-blue PeLEDs maintain a constant spectrum peak with CIE chromaticity coordinates of (0.136, 0.051) under a steady driving current for 60 min.

Strategic use of dopants and device structure optimization for enhanced color gamut and efficiency in organic light-emitting diodes microdisplay applications

Strategic use of dopants and device structure optimization for enhanced color gamut and efficiency in organic light-emitting diodes microdisplay applications

Landau-Levich Scaling for Optimization of Quantum Dot Layer Morphology and Thickness in Quantum-Dot Light-Emitting Diodes.

Quantum dot (QD) light-emitting diodes (QLEDs) are promising candidates for next-generation displays because of their high efficiency, brightness, broad color gamut, and solution-processability. Large-scale solution-processing of electroluminescent QLEDs poses significant challenges, particularly concerning the precise control of the active layer's thickness and uniformity. These obstacles directly impact charge transport, leading to current leakage and reduced overall efficiency. Blade-coating is a prevalent and scalable solution processing technique known for its speed and minimal waste. Additionally, it allows for continuous "roll-to-roll" processing, making it highly adaptable in various applications. In this study, we demonstrate the precise control of blade speed in the Landau-Levich regime to create a uniform QD emission layer, using a commercial CdSe/ZnS QD as a representative example. QDs assemble into different morphologies on glass and the underlying layers of the QLED device due to variations in interaction energy. The QD film thickness can be modified from monolayer to multilayer by adjusting blade speed, which can be predicted by fitting the Landau-Levich-Derjaguin theory. The optimal speed at 7 mm/s results in a QD film with a surface coverage of around 163% and low roughness (1.57 nm mean square height). The QLED external quantum efficiency (EQE) of approximately 1.5% was achieved using commercially available CdSe/ZnS QDs with low photoluminescence quantum yield (PLQY), and an EQE of around 7% has been obtained using lab-made InP/ZnSe/ZnS QDs having a solution PLQY of 74%. All-blade-coated CdSe-QLEDs are further demonstrated by adopting the optimized speed for the QD layer. This method demonstrates significant potential for developing low-cost, reproducible, and scalable QLED technologies with uniform emission characteristics and low-waste production.

Light-Emitting Diodes Based on Metal Halide Perovskite and Perovskite Related Nanocrystals.

Light-emitting diodes (LEDs) based on halide perovskite nanocrystals have attracted extensive attention due to their considerable luminescence efficiency, wide color gamut, high color purity, and facile material synthesis. Since the first demonstration of LEDs based on MAPbBr3 nanocrystalswasreported in 2014, the community has witnessed a rapid development in their performances. In this review, a historical perspective of the development of LEDs based on halide perovskite nanocrystals is provided and then a comprehensive survey of current strategies for high-efficiency lead-based perovskite nanocrystals LEDs, including synthesis optimization, ion doping/alloying, and shell coating is presented. Then the basic characteristics and emission mechanisms of lead-free perovskite and perovskite-related nanocrystals emitters in environmentally friendly LEDs, from the standpoint of different emission colors are reviewed. Finally, the progress in LED applications is covered and an outlook of the opportunities and challenges for future developments in this field is provided.

Nano-ridge plasmonic structural colors fabricated by roll-to-roll hot-embossing

Structural colors are now applied in many areas, like traceable anti-counterfeiting and wearable technologies, due to their durability and wide color gamut. However, the large-scale deployment of structural colors has been limited by the complexity of device structures and, subsequently, the realization of cost-effective fabrication. In this work, we introduce a plasmonic structural color based on periodical nano-ridges, which can be nano-imprinted on an aluminum-polyurethane-polyethylene terephthalate film. These aluminum nano-ridges can excite metal and dielectric hybrid waveguide modes with surface plasmonic resonance for transverse magnetic (TM) lights, resulting in broad dips in the reflection spectrum. The design and key optical features of the proposed device structures are presented. The fabricated structures show desirable features, including angle-dependent and polarization-dependent chromatic reflections. This structure could be mass-produced using a conventional roll-to-roll hot-embossing nano-imprinting process on pre-prepared films, making it suitable for low-cost anti-counterfeiting applications.

Hydrazide Molecular Configuration Induced Phase Regulation and Defect Passivation Enable Efficient Quasi‐2D Blue Perovskite Light‐Emitting Diodes

AbstractPerovskite light‐emitting diodes (PeLEDs) have demonstrated significant potential in the display sector, attributed to their wide color gamut, narrow emission spectra, and cost‐effectiveness. Despite the rapid advancements in red and green PeLEDs, the attainment of high brightness and high external quantum efficiency (EQE) for blue PeLEDs remains a considerable challenge, which substantially limits their practical applications in white lighting and optical communication. In this study, a method for the passivation of blue quasi‐2D perovskites using hydrazide derivatives with varying alkyl chain lengths is presented. Density functional theory analysis indicates that hydrazide derivatives can effectively adsorb onto halogen vacancies, thereby reducing charge trapping states associated with undercoordinated Pb2+. Experimental results demonstrate that the optimal hydrazide derivative can better eliminate non‐radiative recombination loss, suppress ions migration, and regulate phase distribution, facilitating smoother energy transfer. Through this approach, stable sky‐blue PeLEDs are achieved with an EQE of 14.5% and a maximum luminance of 2659 cd m−2. This work offers a systematic understanding of hydrazide additive design, which will further enhance the performance and stability of blue quasi‐2D PeLEDs.

SN2-mediated decoupled precursor provision enables large-scale production of monodisperse lead halide perovskite quantum dots in a single reactor

Quantum-confined lead-halide perovskite nanocrystals (QPNCs) are a promising optoelectronic semiconductor owing to their exceptional fluorescence and the size- and dimension-tunable optical properties. QPNCs having low formation energy encounter challenges in accurately regulating the nucleation and crystal growth stages during injection-based syntheses using lead halide reagents. Here, we introduce a non-injection, one-pot synthetic approach based on bimolecular nucleophilic substitution (SN2) and thermolysis reactions of the decoupled metal and halide precursors for the large-scale production of monodisperse CsPbX3-QPNCs (X = Cl, Br, I). This approach facilitates a homogeneous supply of halide anions and metal cations, enabling the precise control over the nucleation and crystal growth stages in the isolated size-focused region. Monodisperse CsPbX3-QPNCs achieve high color purity across the RGB color gamut by adjusting size, dimensionality, and halide composition, and can be produced on an ultra-large scale.

Dynamic Multicolor Display with Wide Color Gamut Enabled by Vanadium Oxide‐Based Fabry–Pérot Electrochromic Nanocavities

Dynamic Multicolor Display with Wide Color Gamut Enabled by Vanadium Oxide‐Based Fabry–Pérot Electrochromic Nanocavities

Multi-primary-color light-emitting diode display schemes in terms of color gamut, blue light hazard, and circadian rhythm

Multi-primary-color light-emitting diode display schemes in terms of color gamut, blue light hazard, and circadian rhythm

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.

Influence of Lewis basicity on the S2- induced synthesis of 0D Cs4PbBr6 hexagonal nanocrystals and its implications for optoelectronics.

Perovskite nanocrystals (NCs) with their excellent optical and semiconductor properties have emerged as primary candidates for optoelectronic applications. While extensive research has been conducted on the 3D perovskite phase, the zero-dimensional (0D) form of this promising material in the NC format remains elusive. In this paper, a new synthesis strategy is proposed. According to the Hard-Soft Acid-Base (HSAB) principle, a novel class of hexagonal semiconductor nanocrystals (Cs4PbBr6 HNCs) derived from 0D perovskite Cs4PbBr6 is synthesized by doping an appropriate amount of PbS precursor solution into bromide. These Cs4PbBr6 HNCs are characterized and compared in detail to CsPbBr3 cubic nanocrystals (CsPbBr3 CNCs) as a reference. The Cs4PbBr6 HNCs exhibit significantly enhanced photoluminescence (PL) compared to CsPbBr3 CNCs, with an external quantum efficiency (EQE) reaching 24.19%. Furthermore, they demonstrate superior UV stability compared to CsPbBr3 CNCs. Comparative analysis of their physical properties and morphology, along with detailed investigations into band structures, density of states, and lifetime decay through DFT calculations, is provided. The practical application potential is validated by encapsulating them into backlight LEDs, covering 121.5% and 90.7% of the color gamut of NTSC and Rec. Our research provides comprehensive insights into the photophysical properties of inorganic halide perovskite nanomaterials and explores their potential in the field of optoelectronics.

Achieving High Blue Light Excited Quantum Efficiency in CsPbBr3 Quantum Dots through SiO2-Modified Glass Network Structure for Wide Color Gamut Displays

Achieving High Blue Light Excited Quantum Efficiency in CsPbBr3 Quantum Dots through SiO2-Modified Glass Network Structure for Wide Color Gamut Displays

Enhanced Chromaticity and Dual Emission in Double-Site Mn4+-Activated KLiTiF6 Red Phosphor for Wide Color Gamut Displays

Mn4+-activated fluoride phosphors are pivotal for white LEDs due to their narrow-band red emission, which is essential for achieving wide color gamut displays. A red shift in the emission spectrum,...

Liquid‐Crystal‐Powered Metasurfaces for Electrically and Thermally Switchable Photorealistic Nanoprinting and Optical Security Platform

AbstractActive or reconfigurable metasurfaces have been considered a promising paradigm for dynamic structural coloration and are starting to find their way into the ultra‐compact integrated optical display and color printing platforms. Generally, an ideal dynamic structural color platform requires full hue‐saturation‐brightness (HSB) control, high switching contrast, and a simple operation manner. Unfortunately, to date, it remains challenging to simultaneously achieve all these features using previous approaches. Here, a novel electrically and thermally switchable reflective nanoprinting platform is reported by integrating polarization‐sensitive silver nanogroove arrays with a twisted nematic LC cell. Compared to conventional LC‐assisted dynamic nanoprinting, the device can simultaneously achieve superior color purity, wider gamut, and higher switching contrast. Moreover, through the implementation of a sub‐pixels scheme, arbitrary colors in the color gamut can be created by a mixture of red, green, and blue (RGB) channels at different ratios. As a proof of concept, dynamic switching of photorealistic nanoprinting with full HSB control at a high pixel density (>4,000 pixels per inch) as well as information switching and steganography are demonstrated, suggesting that the device possesses great potential in optical display and information security applications.

Ultrafast Laser Inkless Full‐Color Printing on Flexible and Thermolabile Substrates

AbstractLaser‐induced structural color technology holds great promise for the mass‐production of structural colors of wide color gamut, high stability, and low cost. However, its application to flexible and thermolabile substrates (such as plastics and paper) is currently hindered by the reliance on high‐temperature processes or metal substrates. Here, an ultrafast laser inkless printing technology is proposed to address this challenge. By optimizing the magnetron sputtering process with a pre‐sintered TiN target, the reflective TiN layer can be prepared at room temperature, on which coated an absorptive TiN layer to produce the TiN hybrid film. Under laser irradiation, this hybrid film is transformed into an “oxide‐absorptive‐reflective” tri‐layer film structure when the upper absorptive TiN layer is oxidized. In this case, the thicknesses of the oxide and absorptive layers can be adjusted by modifying the total accumulated laser fluence. This enables the tuning of the double‐absorption wavelength, thereby obtaining basic structural colors for printing. The high durability of the obtained structural colors is verified through various aging tests. Notably, this technology is successfully applied to flexible and thermolabile substrates, including plastics and cardboard paper, which may further promote the practical application of laser‐induced structural color technology.

Physics-Constrained Deep Learning for Security Ink Colorimetry with Attention-Based Spectral Sensing.

The proliferation of sophisticated counterfeiting poses critical challenges to global security and commerce, with annual losses exceeding $2.2 trillion. This paper presents a novel physics-constrained deep learning framework for high-precision security ink colorimetry, integrating three key innovations: a physics-informed neural architecture achieving unprecedented color prediction accuracy (CIEDE2000 (ΔE00): 0.70 ± 0.08, p < 0.001), advanced attention mechanisms improving feature extraction efficiency by 58.3%, and a Bayesian optimization framework ensuring robust parameter tuning. Validated across 1500 industrial samples under varying conditions (±2 °C, 30-80% RH), this system demonstrates substantial improvements in production efficiency with a 50% reduction in rejections, a 35% decrease in calibration time, and 96.7% color gamut coverage. These achievements establish new benchmarks for security printing applications and provide scalable solutions for next-generation anti-counterfeiting technologies, offering a promising outlook for the future.

Enabling Multicolor Information Encryption: Oleylammonium-Halide-Assisted Reversible Phase Conversion between Cs4PbX6 and CsPbX3 Nanocrystals.

Recently, halide perovskites have been recognized for their thermochromic characteristics, showing significant potential in information encryption applications. However, the limited luminescence color gamut hinders the encryption of complex multicolor information. Herein, for the first time, multicolor thermochromic perovskites with luminescence covering the entire visible spectrum have been designed. Oleylammonium halide salts facilitate a reversible phase transformation between nonluminescent Cs4PbX6 nanocrystals (NCs) and luminescent CsPbX3 NCs upon heating or cooling. This process occurs without the need for external addition or removal of ligands or metal salts, enabling efficient and intelligent information encryption. A proof-of-concept demonstration successfully encrypts and decrypts multicolor digital information. This work not only advances the understanding of phase transformations in perovskites but also highlights their significant potential for information encryption applications.

Blue Quantum Dot Light-Emitting Diodes toward Full-Color Displays: Materials, Devices, and Large-Scale Fabrication.

Quantum dots (QDs) light-emitting diodes (QLEDs) are gaining significant interest for the next generation of display and lighting applications because of their wide color gamut, cost-effective solution processability, and good stability. The last decades have witnessed rapid advances in improving their efficiency and lifetime. So far, among the three primary colors of QLEDs devices, the performance of blue QLEDs is considerably inferior to that of green and red ones including Cd-based and Cd-free devices, which is a key bottleneck hindering QLEDs' application. This mini-review describes recent advances of blue Cd-based and Cd-free QLEDs from materials to device engineering, in particular, elaborating the essential factors that limit their performance and the degradation mechanisms. We also discuss the progress and challenges of large-scale displays. Finally, we propose possible approaches to improve the performance of the blue QLEDs, including QDs materials and device architecture optimization, and summarize potential applications in this stimulating field.