Gamut Research Articles

TiO2 doping promoted nucleation of CsPbX3 (X = Cl, Br, I) quantum dots in glass with improved luminescent performance and stability

Stability hinders further development of all-inorganic CsPbX3 (X = Cl, Br, I) quantum dots (QDs) although they exhibit promising prospects in optoelectronic applications. Coating perovskite quantum dots (PQDs) with a glass network to form QD glass can significantly improve their stability. However, the dense glass network degrades their luminescent performance. In this work, the crystallization behavior of PQDs in glass and better luminescence properties are prompted by introducing titanium dioxide into borosilicate glass. The luminescence intensity of TiO2-doped CsPbBr3 QD glass is increased by 1.6 times and the PLQY is increased from 49.8 % to 79 % compared to the undoped glass. Evidence proves that the improved properties are attributed to the enhanced nucleation effect of titanium dioxide during the annealing process. Benefiting from the densification of the glass network caused by titanium dioxide doping, the stability of the PQD glass is further improved. LED devices with an ultra-wide color gamut that fully covers the NTSC1953 standard and achieves 128.6 % of the NTSC1953 standard as well as 91.1 % of the Rec.2020 standard were fabricated by coupling PQD glass powder, demonstrating promising commercial applications of PQD glass in optoelectronic displays.

P‐176: New liquid crystal materials for high‐contrast displays of the fringe‐field switching mode

Since the establishment of liquid crystal display industries, larger sizes, faster response, higher contrast ratio, higher resolution and lower power consumption have become a pursuing target of various panel suppliers. Considering the marvelous viewing angle of the fringe‐field switching (FFS) mode, FFS displays with a higher contrast ratio are able to show more details in the dark pictures, resulting in a much better viewing experience. Herein, to develop the next‐generation liquid crystal (LC) materials for high‐contrast FFS panels, various high‐contrast LC (HCLC) materials were designed. By minimizing Δn and maximizing Kave, HCLCs exhibited lower light leakage in dark states, leading to a higher contrast ratio compared to the reference. Two HCLCs for improving the operation voltage, transmittance, contrast ratio and response time were developed by optimizing the properties of HCLC materials. Furthermore, FFS monitors with a contrast ratio of 2820:1 and a color gamut of 96.4% NTSC were demonstrated.

49‐3: Invited Paper: High‐Resolution Color‐Reflective Bistable Cholesteric Liquid Crystal Technology for Signage Applications

An optimized color‐reflective LCD with high optical performances and cost‐effective structure has been proposed by association with cholesteric liquid crystal technology. By way of a color dithering algorithm, the cholesteric liquid crystal display (Ch‐LCD) can visualize a 24‐bit RGB color pixel and display over 16 million colors. Moreover, the waveform module (WF) is applied to emulate the display timing controller, which is a lowcost and more accessible way to drive the Ch‐LCD. In this paper, we demonstrated a 13.3‐inch passive matrix (PM) driven Ch‐LCD with a high resolution of 202 PPI, high reflectance of 30%, and high color gamut of 20%, which is suitable for electronic signage applications.

77‐2: Research on Suppressing the Electrical Crosstalk of Tandem OLED Sub‐pixels

Tandem OLED has attracted widely attention in display application due to its ability to reduce power consumption and increase lifetime simultaneously. The display industry is currently focusing on developing the structure and the process for tandem OLED. In the tandem OLED device, the common layer, including charge generation layer (CGL), will not only transport charge carriers vertically, but also transport the charge horizontally to adjacent sub‐pixels, resulting in electrical crosstalk. Moreover, the decrease of tandem OLED current will seriously affect the color gamut of display under low gray levels from 81.3% to 48.26%. Here, we provide theoretical simulation and some solutions to suppress the electrical crosstalk and optimize uniformity of tandem OLED display, providing some guidance for the development of tandem OLED technology.

Deep-learning-assisted inverse design of polarization-multiplexed structural color filters with ultrahigh saturation based on all-dielectric metasurface

Although great progress has been made for metasurface-based structural color filters, there are still significant challenges in encoding metasurfaces with complex color images, especially in high saturation or multi-channel cases, where traditional iterative optimization calculations demand substantial computational resources. Here, we proposed a dual-channel multilayered all-dielectric metasurface that can generate structural colors accounting for 224% Standard RGB space, 168% Adobe RGB space and 78% of the 1931 CIE chromaticity space under vertically-polarized incidence. A deep learning-based designing approach is introduced to significantly reduce the computing consumption while maintaining high accuracy. Numerical simulations further demonstrated that the proposed design method is effective for encoding both complementary and independent images with high saturation and wide color gamut. Therefore, the proposed color filters may find potential applications in image display, information encryption and optical anti-counterfeiting.

P‐36: Optimizing TV Gamma and Correlated Color Temperature Settings for Enhanced Viewer Satisfaction: A Comprehensive Study on Backlight Brightness and Color Gamut Influences

We investigate user acceptance of image quality across various TV configurations, highlighting the importance of customizing adjustments in gamma and correlated color temperature settings. The findings indicate that aligning these settings with TV performance can enhance the overall visual experience, closing the gap between technical standards and user preferences.

92‐4: Invited Paper: MicroLED Display Technology Entering Mass Production: Opportunities and Challenges in the New Era

MicroLED display is an innovative display technology with high brightness, wide color gamut, high aperture ratio, and excellent reliability. MicroLED represents a new era in display technology, and it is rapidly entering the mass production phase. It can be used in traditional display applications and can also be applied to various innovative display technologies, such as AR glasses, transparent displays, electric vehicles, or other new use cases, expanding the application of displays into more fields. Therefore, the most critical challenge is how to rapidly reduce costs to enable the widespread adoption of MicroLED.

60‐4: Minimal Efficiency Degradation and Elevated Radiometric Power Density of Ultraviolet‐A Micro‐LED with Homoepitaxial Structure

As display technology continues to advance, UVA micro‐LEDs are becoming increasingly important in a variety of display and beyond‐display applications. In this study, we investigate the optoelectronic characteristics of UVA micro‐LEDs based on a homogeneously epitaxial structure on freestanding gallium nitride (GaN) substrates. The device exhibits a central wavelength of 390 nm, positioned at the overlap of UVA and visible light spectra. It demonstrates an impressively low ideality factor of 1.49 at 2.86 V and a series resistance of 9.88 O beyond 3 V. Optically, our device shows virtually no wavelength shift across a wide current density range of 0.1‐1000 A/cm2, indicating exceptional optical stability and color accuracy. The emitted light is typical purple, reaching an expansive color gamut of 115.3% of Rec.2020. Furthermore, the GaN‐on‐GaN structure, with its superior crystal structure and heat dissipation properties, results in a very low droop ratio in EQE. This ensures sustained highpower output at high current densities, showcasing great potential in applications such as 3D printing, maskless photolithography, and fluorescence tagging.

Multicolor tunable persistent luminescence mechanism in well-designed inorganic composites.

Herein, by ball milling CsPb(Br/I)3 quantum dot glass powder with Sr2MgSi2O7:Eu2+, Dy3+ phosphor, multicolor tunable long persistent luminescence (LPL) in inorganic composites with more than 700 min attenuation time can be obtained via a radiation photon reabsorption process. Attractively, the wide color gamut of LPL spectra overlaps the National Television System Committee space 74%. Notably, the luminescence intensity remains stable when the inorganic composites are composed with UV light for 100 h. Finally, practical anticounterfeiting application is successfully realized based on the prepared LPL inorganic composites. This work provides a new, to the best of our knowledge, perspective to achieve polychromatic adjustment of LPL.

Generation of Wide Color Gamut in a Collisional and Magnetized Plasma by Laser‐Induced Coloration on Composite Structure Surfaces

AbstractIn this paper, a new scheme for generating a wide gamut of structural colors on the thin‐film‐stack‐based (TFSB) substrates is proposed. The TFSB surfaces consist of titanium/random gold nanoparticles (AuNPs) and titanium/ random gold and copper nanoparticles (Au+CuNPs), which can trigger more resonance absorption and widen the color gamut. The electric fields in two designed structures are simulated, and the results showed that the random distribution of AuNPs and Au+CuNPs enhance the uniform local surface plasmon resonance (LSPR) response. This enhancement is crucial in broadening the coverage of the reflection spectrum, which enables the generation of a wide range of colors, including green and red. The influence of laser parameters on the color of TFSB substrates and tested their durability in terms of time is analyzed. Finally, a color palette and made structural color patterns on TFSB by nanosecond pulsed laser are prepared. The proposed new scheme can be easily fabricated by magnetron sputtering without requiring additional procedures, which can open new perspectives in plasmonic colors. This work demonstrates that the promising potential of methods in creating a wide color gamut on metallic surfaces. Additionally, it serves as a means to store information for the preservation and protection of traditional cultures.

Local Light Field Control Enables Efficient Quantum Dot Color Conversion Films for Mini‐LED Backlit Displays

AbstractQuantum dot (QD) color conversion films (QD‐CCFs) are used in ultrahigh definition (UHD) Mini‐LED backlit displays due to their narrow band emission and high color purity. However, their poor light conversion efficiency (LCE) leads to greater film thickness and thus high cost. Herein, this study proposes a local light field control strategy to enhance the LCE of QD‐CCFs using high‐refractive BN nanosheets. The LCEs of the green and red QD‐CCFs can increase from 29.9% and 34.8% to 67.4% and 91.0% after adding BN nanosheets, respectively. Combining the experimental data with the finite‐difference time domain (FDTD) simulations, the enhanced LCEs can be attributed to observably increased blue light absorption and improved light extraction efficiency of the light emitted from QDs. The white Mini‐LEDs, prepared by integrating the optimized QD‐CCFs containing BN nanosheets with blue Mini‐LED chips, show a high luminous efficiency of 70.2 lm W−1, a high external quantum efficiency of 36.2%, and a wide color gamut of 96.3% Rec. 2020 standards. This work provides an interesting idea for designing high‐efficiency QD‐CCFs toward low‐cost UHD Mini‐LED backlit displays.

Narrowband room temperature phosphorescence of closed-loop molecules through the multiple resonance effect

Luminescent materials with narrowband emission show great potential for diverse applications in optoelectronics. Purely organic phosphors with room-temperature phosphorescence (RTP) have made significant success in rationally manipulating quantum efficiency, lifetimes, and colour gamut in the past years, but there is limited attention on the purity of the RTP colours. Herein we report a series of closed-loop molecules with narrowband phosphorescence by multiple resonance effect, which significantly improves the colour purity of RTP. Phosphors show narrowband phosphorescence with full width at half maxima (FWHM) of 30 nm after doping into a rigid benzophenone matrix under ambient conditions, of which the RTP efficiency reaches 51.8%. At 77 K, the FWHM of phosphorescence is only 11 nm. Meanwhile, the colour of narrowband RTP can be tuned from sky blue to green with the modification of methyl groups. Additionally, the potential applications in X-ray imaging and display are demonstrated. This work not only outlines a design principle for developing narrowband RTP materials but also makes a major step forward extending the potential applications of narrowband luminescent materials in optoelectronics.

Excited-State Engineering Enables Efficient Deep-Blue Light-Emitting Diodes Exhibiting BT.2020 Color Gamut.

Organic luminescent materials that exhibit thermally activated delayed fluorescence (TADF) can convert non-emissive triplet excitons into emissive singlet states through a reverse intersystem crossing (RISC) process. Therefore, they have tremendous potential for applications in organic light-emitting diodes (OLEDs). However, with the development of ultra-high definition 4K/8K display technologies, designing efficient deep-blue TADF materials to achieve the Commission Internationale de l'Éclairage (CIE) coordinates fulfilling BT.2020 remains a significant challenge. Here, an effective approach is proposed to design deep-blue TADF molecules based on hybrid long- and short-range charge-transfer by incorporation of multiple donor moieties into organoboron multiple resonance acceptors. The resulting TADF molecule exhibits deep-blue emission at 414nm with a full width at half maximum (FWHM) of 29nm, together with a thousand-fold increase in RISC rate. OLEDs based on the champion material achieve a record maximum external quantum efficiency (EQE) of 22.8% with CIE coordinates of (0.163, 0.046), approaching the coordinates of the BT.2020 blue standard. Moreover, TADF-assisted fluorescence devices employing the designed material as a sensitizer exhibit an exceptional EQE of 33.1%. This work thus provides a blueprint for future development of efficient deep-blue TADF emitters, representing an important milestone towards meeting the blue color gamut standard of BT.2020.

Fast image recoloring for red–green anomalous trichromacy with contrast enhancement and naturalness preservation

Color vision deficiency (CVD) is an eye disease caused by genetics that reduces the ability to distinguish colors, affecting approximately 200 million people worldwide. In response, image recoloring approaches have been proposed in existing studies for CVD compensation, and a state-of-the-art recoloring algorithm has even been adapted to offer personalized CVD compensation; however, it is built on a color space that is lacking perceptual uniformity, and its low computation efficiency hinders its usage in daily life by individuals with CVD. In this paper, we propose a fast and personalized degree-adaptive image-recoloring algorithm for CVD compensation that considers naturalness preservation and contrast enhancement. Moreover, we transferred the simulated color gamut of the varying degrees of CVD in RGB color space to CIE L*a*b* color space, which offers perceptual uniformity. To verify the effectiveness of our method, we conducted quantitative and subject evaluation experiments, demonstrating that our method achieved the best scores for contrast enhancement and naturalness preservation.

Aluminum Carboxylate Modification Enabled Efficient and Stable Perovskite-Polystyrene Thin Films for Light-Emitting Applications.

Lead halide perovskite nanocrystals (PNCs) have demonstrated great potential in emerging display technologies. However, the practical application of PNCs is hindered by the inherent instability of their ionic surface. Here, we proposed a surface modification approach to enhance the stability of CsPbBr3 PNCs by postsynthetic treatment with aluminum phenylbutyrate (Al(PA)3). Our study reveals that Al(PA)3 displaces ammonium ligands and binds tightly on surface halide, providing excellent air and moisture resistance while preserving a high quantum efficiency of 81.6%. The modified PNCs maintain a constant photoluminescence intensity under continuous UV light illumination for 500 h. Additionally, the Al(PA)3 ligand is compatible with styrene, enabling homogeneous dispersion of PNCs in polystyrene matrices to form bright and uniform PNC-PS thin films. We demonstrated the application of the composite films for display backlighting, which exhibits a wide color gamut of 125% NTSC. The result highlights the potential of AlPA-modified PNCs in light-emitting and other optoelectronic devices.

Fine-Tuning Crystal Structures of Lead Bromide Perovskite Nanocrystals through Trace Cadmium(II) Doping for Efficient Color-Saturated Green LEDs.

Decreasing perovskite nanocrystal size increases radiative recombination due to the quantum confinement effect, but also increases the Auger recombination rate which leads to carrier imbalance in the emitting layers of electroluminescent devices. Here, we overcome this trade-off by increasing the exciton effective mass without affecting the size, which is realized through the trace Cd2+ doping of formamidinium lead bromide perovskite nanocrystals. We observe an ~2.7 times increase in the exciton binding energy benefiting from a slight distortion of the [BX6]4- octahedra caused by doping in the case of that the Auger recombination rate is almost unchanged. As a result, bright color-saturated green emitting perovskite nanocrystals with a photoluminescence quantum yield of 96 % are obtained. Cd2+ doping also shifts up the energy levels of the nanocrystals, relative to the Fermi level so that heavily n-doped emitters convert into only slightly n-doped ones; this boosts the charge injection efficiency of the corresponding light-emitting diodes. The light-emitting devices based on those nanocrystals reached a high external quantum efficiency of 29.4 % corresponding to a current efficiency of 123 cd A-1, and showed dramatically improved device lifetime, with a narrow bandwidth of 22 nm and Commission Internationale de I'Eclairage coordinates of (0.20, 0.76) for color-saturated green emission for the electroluminescence peak centered at 534 nm, thus being fully compliant with the latest standard for wide color gamut displays.

Personnel Detection in Dark Aquatic Environments Based on Infrared Thermal Imaging Technology and an Improved YOLOv5s Model.

This study presents a novel method for the nighttime detection of waterborne individuals using an enhanced YOLOv5s algorithm tailored for infrared thermal imaging. To address the unique challenges of nighttime water rescue operations, we have constructed a specialized dataset comprising 5736 thermal images collected from diverse aquatic environments. This dataset was further expanded through synthetic image generation using CycleGAN and a newly developed color gamut transformation technique, which significantly improves the data variance and model training effectiveness. Furthermore, we integrated the Convolutional Block Attention Module (CBAM) at the end of the last encoder's feedforward network. This integration maximizes the utilization of channel and spatial information to capture more intricate details in the feature maps. To decrease the computational demands of the network while maintaining model accuracy, Ghost convolution was employed, thereby boosting the inference speed as much as possible. Additionally, we applied hyperparameter evolution to refine the training parameters. The improved algorithm achieved an average detection accuracy of 85.49% on our proprietary dataset, significantly outperforming its predecessor, with a prediction speed of 23.51 FPS. The experimental outcomes demonstrate the proposed solution's high recognition capabilities and robustness, fulfilling the demands of intelligent lifesaving missions.

Fine‐Tuning Crystal Structures of Lead Bromide Perovskite Nanocrystals through Trace Cadmium(II) Doping for Efficient Color‐Saturated Green LEDs

AbstractDecreasing perovskite nanocrystal size increases radiative recombination due to the quantum confinement effect, but also increases the Auger recombination rate which leads to carrier imbalance in the emitting layers of electroluminescent devices. Here, we overcome this trade‐off by increasing the exciton effective mass without affecting the size, which is realized through the trace Cd2+ doping of formamidinium lead bromide perovskite nanocrystals. We observe an ~2.7 times increase in the exciton binding energy benefiting from a slight distortion of the [BX6]4− octahedra caused by doping in the case of that the Auger recombination rate is almost unchanged. As a result, bright color‐saturated green emitting perovskite nanocrystals with a photoluminescence quantum yield of 96 % are obtained. Cd2+ doping also shifts up the energy levels of the nanocrystals, relative to the Fermi level so that heavily n‐doped emitters convert into only slightly n‐doped ones; this boosts the charge injection efficiency of the corresponding light‐emitting diodes. The light‐emitting devices based on those nanocrystals reached a high external quantum efficiency of 29.4 % corresponding to a current efficiency of 123 cd A−1, and showed dramatically improved device lifetime, with a narrow bandwidth of 22 nm and Commission Internationale de I'Eclairage coordinates of (0.20, 0.76) for color‐saturated green emission for the electroluminescence peak centered at 534 nm, thus being fully compliant with the latest standard for wide color gamut displays.

Mn(II)-Based Metal Halide with Near-Unity Quantum Yield for White LEDs and High-Resolution X-ray Imaging.

Metal halides have drawn great interest as luminescent materials and scintillators due to their outstanding optical properties. Exploring new types of phosphors with easy production processes, excellent photophysical properties, high light yields, and environmentally friendly compositions is crucial and quite challenging. Herein, a novel Mn(II)-based metal halide (4-BTP)2MnBr4 was produced using a facile solvent evaporation method, which exhibited a strong green emission peaking at 524 nm from the d-d transition of tetrahedral-coordinated Mn2+ ion and a near-unity quantum yield. The prepared white light-emitting diode device has a wide color gamut of 100.7% NTSC with CIE chromaticity coordinates of (0.32, 0.32). In addition, (4-BTP)2MnBr4 demonstrates excellent characteristics in X-ray scintillation, including a high light yield of 98 000 photons/MeV, a sensitive detection limit of 37.4 nGy/s, excellent resistance to radiation damage, and successful demonstration of X-ray imaging with high resolution at 21.3 lp/mm, revealing the potential for application in diagnostic X-ray medical imaging and industry radiation detection.

Tri-wavelength blending method for speckle reduction and color space enhancement in laser projection systems

A novel tri-wavelength blending speckle reduction method was proposed and studied both experimentally and theoretically. In the proposed method, a 543 nm diode pumped solid state (DPSS) laser was employed to cooperated with a shorter wavelength 523 nm laser diode (LD) and a common 532 nm DPSS laser. Comparing to the traditional speckle reduction method, the proposed method takes into account both speckle reduction and color space coverage of a project system. It was shown that speckle contrast ratio (SCR) as low as 3.3 % was achieved when the power ratio of 523 nm, 532 nm and 543 nm light were set to 4:1:1. The effect on the color gamut after the use of tri-wavelength blending method was also investigated. It was found that by using the proposed tri-wavelength blending green lasers together with the commercially available red (635 nm) and blue (467 nm) laser diodes, a color space coverage as large as 97.6 % of the Rec.2020 color gamut can be achieved.