Light Display Research Articles

In Situ Synthesis of Br‐Rich CsPbBr3 Nanoplatelets: Enhanced Stability and High PLQY for Wide Color Gamut Displays

AbstractThis study presents the Br‐rich in situ synthesis of blue‐emitting 2D CsPbBr3 nanoplatelets (NPLs) with various Br/Pb ratios using ZnBr2 as a Br precursor to enhance Br ion adsorption significantly. This leads to effective passivation of surface defects, particularly Pb−Br bonds, by increasing the positive charge density around Pb atoms, thus creating a stable bonding environment and reducing defect formation. Consequently, the photoluminescence quantum yield (PLQY) improves from 31.15% for a Br/Pb ratio of 2 to 87.2% for a ratio of 6. NPLs with a Br/Pb ratio of 6 also exhibit longer lifetimes (16.69 ns) and slower bleach recovery dynamics, indicating fewer non‐radiative recombination pathways and effective exciton dynamics. Additionally, NPLs with the Br/Pb ratio of 6 demonstrated better thermal stability, with an activation energy of 124.3 meV, indicating stronger exciton binding. These NPLs also exhibited enhanced stability, with UV tolerance at 43.9% and water resistance at 23.8%, making them suitable for displays and lighting. Furthermore, Br‐passivated CsPbBr3 NPLs are used as blue emitters in prototype white LEDs, achieving a wide color gamut, 126.6% of the National Television Standards Committee and 94.5% of Rec. 2020, demonstrating their potential for high‐quality lighting and advanced display technologies.

Enhancing Blue Polymer Light-Emitting Diode Performance by Optimizing the Layer Thickness and the Insertion of a Hole-Transporting Layer.

Polymer light-emitting diodes (PLEDs) hold immense promise for energy-efficient lighting and full-color display technologies. In particular, blue PLEDs play a pivotal role in achieving color balance and reducing energy consumption. The optimization of layer thickness in these devices is critical for enhancing their efficiency. PLED layer thickness control impacts exciton recombination probability, charge transport efficiency, and optical resonance, influencing light emission properties. However, experimental variations in layer thickness are complex and costly. This study employed simulations to explore the impact of layer thickness variations on the optical and electrical properties of blue light-emitting diodes. Comparing the simulation results with experimental data achieves valuable insights for optimizing the device's performance. Our findings revealed that controlling the insertion of a layer that works as a hole-transporting and electron-blocking layer (EBL) could greatly enhance the performance of PLEDs. In addition, changing the active layer thickness could optimize device performance. The obtained results in this work contribute to the development of advanced PLED technology and organic light-emitting diodes (OLEDs).

Controllable morphology, excellent stability and non-equivalent doping-induced optical properties of Mn4+-activated K2NaScF6 red phosphor for high-quality warm WLED

Currently, Mn4+ activated fluoride red phosphor has been widely studied to improve the optical performance of white light-emitting diode (WLED) in the field of high-efficiency lighting and wide color gamut backlight display. In this paper, a series of red-emitting K2NaScF6:Mn4+ phosphors are synthesized by a simple co-precipitation method with a non-equivalent substitution of Mn4+ for Sc3+ at room temperature. The crystal structure, morphology and elemental composition of K2NaScF6:Mn4+ phosphors prepared using different reaction conditions are systematically investigated. Interestingly, the K2NaScF6:Mn4+ phosphors exhibit narrowband red emission with low correlated color temperature (CCT), high color purity and short fluorescence lifetime. Compared to equivalent doping, the mechanism of short fluorescence lifetime caused by non-equivalent doping has also been systematically discussed. The optimal doping concentration is determined by setting a series of Mn4+ doping concentrations and the concentration quenching mechanism is analyzed. The crystal field strength (Dq), Racah parameters (B and C) and nephelauxetic ratio (β1) are calculated in detail to evaluate the crystal field environment of Mn4+ in K2NaScF6. The good water resistance of the as-prepared sample K2NaScF6:Mn4+ is verified by comparing with the commercially available phosphor K2SiF6:Mn4+. Moreover, the thermal stability is also analyzed by calculating the activation energy (Ea), chromaticity shift (ΔE) and chromaticity coordinate variation (CCV). Importantly, the as-packaged warm WLED (InGaN chip + YAG:Ce3+ + K2NaScF6:Mn4+) has excellent optical properties (CCT = 4082 K, color rendering index (CRI, Ra = 91.2) and luminous efficiency (LE) = 78.86 lm/W), and it exhibits good output stability at high drive currents. In summary, our work demonstrates that K2NaScF6:Mn4+ red phosphors possess a great potential application in warm WLED for the indoor lighting.

Five-Surface Phosphor-in-Glass for Enhanced Illumination and Superior Color Uniformity in Large-View Scale LEDs.

A novel five-surface phosphor-in-glass (FS-PiG) structure for high illumination and excellent color uniformity in large-view scale LEDs for sensor light source application is demonstrated. YAG phosphor (Y3Al5O12:Ce3+) was uniformly mixed with ceramic and sintered at 680 °C to form a phosphor wafer. Sophisticated laser engraving was employed on the phosphor wafer to form saddle-shaped large-view scale FS-PiG LEDs. The performance of the FS-PiG LEDs exhibited an illumination of 401 lm, average color temperature (CCT) of 5488 K ± 110 K, and color coordinates (CIE) of (0.3179 ± 0.003, 0.3352 ± 0.003). In contrast to convention single-surface phosphor-in-glass (SS-PiG) LEDs, the performance exhibited an illumination of 380 lm, average CCT of 5830 K ± 758 K, and CIE of (0.3083 ± 0.07, 0.3172 ± 0.07). These indicated that the performance of the FS-PiG LEDs was higher than the SS-PiG LEDs for illumination, CCT, and CIE by 1.7, 7, and 23 times, respectively. Furthermore, the FS-PiG LEDs demonstrate a lower lumen loss of 2% and a reduced chromaticity shift of 5.4 × 10-3 under accelerated aging at 350 °C for 1008 h, owing to the high ceramic melting temperature of up to 510 °C. In this study, the proposed FS-PiG large-view scale LEDs with excellent optical performance and high reliability may be promising candidates to replace the conventional phosphor-in-organic silicone material used in high-power LEDs for the next generation of sensor light sources, display, and headlight applications.

Spectroscopic investigation of novel Eu3+ doped Na2LiAlF6 fluoroaluminate for solid state lighting applications

Red-emitting phosphors are crucial for sustainable white-light-emitting diodes (WLEDs) used in lighting. These materials significantly enhance the lighting and backlit display quality of phosphor-converted white LEDs (pc-WLEDs) by overcoming red deficiency. Luminescent properties of rare earth activated fluoride based inorganic compounds are most investigated due to its excellent spectral characteristics. In this paper we report the novel Na2LiAlF6 luminescent host material activated with Eu3+ rare earth ions synthesized by wet chemical method. The spectral analysis revels the excitation spanning in near UV region while emission spectra depict characteristic peaks transitioned in accordance with 5D0 to 7F1 and 7F2. Effect of concentration quenching, Color purity and temperature studied briefly which demonstrates that the prepared red emitting phosphor is useful in various device applications such as phosphor converted White light emitting diodes for fulfilment of red deficiency, solid state lighting, display technology as an essential red component.

10‐3: Distinguished Paper: Reducing Resolution Loss in Naked Eye 3D Display Using Dual Ferroelectric Liquid Crystal (FLC) Shutters for Time‐multiplexed Light Field Display

Usually, the resolution loss is serious in light field display due to the spatial multiplexing of several neighboring pixels to display images from different directions. With the limitation in the resolution of the flat panel display, the light field 3D display shows insufficient display size, image depth, or resolution. This article utilized the FLC with a fast response at 2 kHz and the optimized charge compensation method to achieve a high refresh time multiplexing method, which can effectively increase the display resolution by up to 32 times and is very promising for light field 3D displays in the future.

P‐135: Towards Passing the Visual Turing Test with Field of Light Displays

Field of Light Displays (FoLDs) promise to allow further increases in realism beyond the limits of conventional 2D displays. While the question of how a conventional display can match the limits of the human visual system has been answered, the same question applied to FoLDs has been given much less attention. In this work, we review a recent acuity‐limited viewer model of resolution at depth for a FoLD display. We validate this model using display simulation. We discuss how this model gives less conservative resolution guidelines than previous models, presenting resolution requirements for passing the visual Turing test.

On-chip integrated metasystem for spin-dependent multi-channel color holography.

On-chip integrated metasurface driven by in-plane guided waves is of great interests in various light-field manipulation applications such as colorful augmented reality and holographic display. However, it remains a challenge to design colorful multichannel holography by a single on-chip metasurface. Here we present metasurfaces integrated on top of a guided-wave photonic slab that achieves multi-channel colorful holographic light display. An end-to-end scheme is used to inverse design the metasurface for projecting off-chip preset multiple patterns. Particular examples are presented for customized patterns that were encoded into the metasurface with a single-cell meta-atom, working simultaneously at RGB color channels and for several different diffractive distances, with polarization dependence. Holographic images are generated at 18 independent channels with such a single-cell metasurface. The proposed design scheme is easy to implement, and the resulting device is viable for fabrication, promising plenty of applications in nanophotonics.

A chromosome-level genome assembly of the disco clam, Ctenoides ales.

The bivalve subclass Pteriomorphia, which includes the economically important scallops, oysters, mussels, and ark clams, exhibits extreme ecological, morphological, and behavioral diversity. Among this diversity are five morphologically distinct eye types, making Pteriomorphia an excellent setting to explore the molecular basis for the evolution of novel traits. Of pteriomorphian bivalves, Limida is the only order lacking genomic resources, greatly limiting the potential phylogenomic analyses related to eyes and phototransduction. Here, we present a limid genome assembly, the disco clam, Ctenoides ales (C. ales), which is characterized by invaginated eyes, exceptionally long tentacles, and a flashing light display. This genome assembly was constructed with PacBio long reads and Dovetail Omni-CTM proximity-ligation sequencing. The final assembly is ∼2.3Gb and over 99% of the total length is contained in 18 pseudomolecule scaffolds. We annotated 41,064 protein coding genes and reported a BUSCO completeness of 91.9% for metazoa_obd10. Additionally, we report a complete and annotated mitochondrial genome, which also had been lacking from Limida. The ∼20Kb mitogenome has 12 protein coding genes, 22 tRNAs, 2 rRNA genes, and a 1,589 bp duplicated sequence containing the origin of replication. The C. ales nuclear genome size is substantially larger than other pteriomorphian genomes, mainly accounted for by transposable element sequences. We inventoried the genome for opsins, the signaling proteins that initiate phototransduction, and found that, unlike its closest eyed-relatives, the scallops, C. ales lacks duplication of the rhabdomeric Gq-protein-coupled opsin that is typically used for invertebrate vision. In fact, C. ales has uncharacteristically few opsins relative to the other pteriomorphian families, all of which have unique expansions of xenopsins, a recently discovered opsin subfamily. This chromosome-level assembly, along with the mitogenome, is a valuable resource for comparative genomics and phylogenetics in bivalves and particularly for the understudied but charismatic limids.

Design and optimization of a flexible fiber-conducted laser light guide plate system

As the demand for slim liquid crystal displays (LCDs) continues to rise in the lighting and visual display fields, the edge-lit backlight structure has received significant attention. However, the edge-lit backlight structure cannot function properly without a light guide plate (LGP) system. This study proposes a novel LGP system employing a laser as the light source and utilizing optical fiber as a waveguide. The design transmits a laser beam into the LGP through an optical fiber, adds microstructure and reflective surfaces, and optimizes the layout of the microstructure. Under the condition that a single point light source is used as the incident light source of the system, the illumination uniformity of the light output surface is finally realized to be as high as 95.8 %, and the light transmission efficiency is as high as 79.7 %. Next, the light output performance of the LGP was measured in the case of single-point light entry on the short side of the strip LGP, and the difference between the test results and the simulation data was within 5 %. The system adopts the fiber optic transmission method of electro-optical separation, which has certain application prospects in the fields of underwater detection, decorative lighting and urban landscape.

Synthesis, coating, and application of a novel cadmium-free red perovskite quantum dot for micro LED technology

This study successfully creats cadmium-free red perovskite QDs through a chemical solution method. The CsPb(Br0.2/I0.8)3 QDs were synthesized by adjusting the bromine-to-iodine ratio and was customized for red emission wavelengths. The QDs were coated with silicon dioxide (SiO2) using a sol-gel method to protect their luminescent characteristics from moisture and oxygenand enhancing interface modification. Finally, pixelated red perovskite QDs were applied to a blue light display as a color conversion layer. The excess blue light penetration was addressed using a 23-layer distributed Bragg reflector (DBR), which redirected surplus blue light back to the QDs, amplifying red light by 30% with a reduced blue light penetration rate of 0.5%. Future research may involve achieving a regionally colored display by precisely aligning and bonding pixelated perovskite QDs, processed for red and previously studied green quantum dots, onto a pre-prepared blue light display.

Effects of Na+, Ga3+ introduction on the luminescence properties of LiAl4O6F: Mn4+ red fluorescent materials

LiAl4O6F (LAOF): Mn4+, Na+, Ga3+ red fluorescent materials were prepared by high temperature solid phase method. The properties of LAOF: Mn4+, Na+, Ga3+ phosphors were characterized by X-ray diffraction (XRD), photoluminescence (PL) spectra, variable temperature spectroscopy, scanning electron microscopy (SEM) and other tests. Under the excitation of 450 nm light, an intense red emission peak was observed around 662 nm, corresponding to the 2Eg→4A2g transition of Mn4+. Compared with Mn4+ single doping, the introduction of Na+, Ga3+ greatly improves the luminescence intensity of LAOF. The photoluminescence quantum yield of the optimal LAOF: 0.2%Mn4+, 0.2%Na+, 3%Ga3+ phosphor was measured to be 41.6%. The prepared sample have excellent thermal and water stability. Meanwhile, the w-LED device with a beneficial luminescence efficiency (LE = 331.7 lm W−1), exhibited good CRI and CCT values. These results indicate that LAOF: Mn4+, Na+, Ga3+ phosphors have potential application prospects as a red component in the field of lighting display.

Exploring Sustainable Clothing Display Design under the Concept of Sustainability

This paper examines sustainable clothing display design under the sustainability concept. The fashion industry faces growing pressure to incorporate sustainability into display design due to environmental concerns and consumer expectations. Employing a comprehensive approach, including literature review, case studies, and consumer surveys, this research establishes a theoretical framework by elucidating sustainable development principles and objectives. Through the analysis of successful sustainable display design cases, particularly within clothing manufacturing and supply chains, the study highlights the pivotal role of brands in this process. Extensive surveys and interviews involving consumers of different demographics and shopping behaviors reveal a positive consumer attitude toward sustainable display design, with sustainability being a significant factor in purchasing decisions. The findings suggest that brands and retailers can enhance their reputation and sales effectiveness by adopting eco-friendly materials, energy-efficient lighting, and reusable display elements. Nevertheless, the study identifies challenges, such as the need for education and standardization in sustainable display design implementation. This study emphasizes the importance of sustainability in clothing display design and its potential to positively impact brand reputation and sales. The research provides valuable guidance to brands and retailers and proposes future research directions, including market segmentation, cultural considerations, and the establishment of sustainable development criteria, to further advance sustainability in the fashion industry.

The design and synthesis of 1-phenylimidazo[1,5-a]pyridine – anthracene-based fluorophore for greenish-yellow organic light emitting diode and warm white LED

Solution-processed OLEDs offer a promising and affordable technology for solid-state lighting and superior self-luminous display panels. Herein, an imidazo[1,5-a]pyridine (ImPy)-based fluorophore decorated with an aromatic π-system anthracene is synthesized by a one-pot condensation approach. From the theoretical study, the energy difference between HOMO and LUMO is 3.1 eV. The molecule shows excellent thermal stability and electrochemical stability. It exhibits efficient intramolecular charge transfer and displays a positive solvatochromic photoluminescence emission band ranging from 528 nm in hexane to 586 nm in acetonitrile with large Stokes’ shift of ∼11,000 cm−1. The OLEDs made of this emitter displayed good device performance with luminous efficiency of 4.4 cd A–1, power efficiency of 2.2 lm W–1 and external quantum efficiency of 3.2%. Additionally, this OLED emitted greenish-yellow light with CIE coordinate (0.34, 0.45) and possessed a low turn-on voltage of 7 V. The material also used in white LED fabrication and the fabricated white LED displayed an excellent color rendering index (CRI), the luminous efficiency of radiation (LER), and correlated color temperatures (CCT) of 89328 lm W–1 , and 4907 K, respectively with CIE coordinate (0.35,0.32).

In Situ Glass Crystallization Enables Narrowband Blue Luminescence for Full‐Spectrum Lighting and Transparent Display

AbstractCurrently, narrowband light‐convertor is critically urgent for preeminent color representation in lighting and display fields, however, the development of target materials still remains challenging. Herein, glass ceramic (GC) composite based on in situ glass crystallization, where the condense glass network structure acts as effective obstructors for long distance ion diffusion, is elaborately designed to inhibit activators’ multi‐sites occupation for acquiring narrowband emitting. Following this strategy, an unprecedented narrowband blue emission of Eu2+‐activators with a peak at 447 nm and full‐width of half maximum (FWHM) of ≈30 nm is developed in a new type of Sr5(PO4)3Cl (SPOCl) GC composite. The Eu2+‐activators’ hindered diffusion inside the GC composite makes preferential and limit occupation of the [Sr1O9] sites, enabling narrowband blue luminescence. Furthermore, the GC composite highlights remarkable performance in high‐power violet‐excitable full‐spectrum lighting and transparent display (TD) prototype fields, due to its high color purity (≈98.1%), photoluminescence quantum field (PLQY, ≈80.5%) and thermal stability (≈82.1%@150 °C). This work not only promotes the profound understanding of the relationship between light manipulation and glass crystallization, but also paves the way toward the implementation of high‐quality lighting and display of GC composites.

Recent Development of Lens Array Fabrication: A Review

The lens array is a multi-functional optical element, which can modulate the incident light such as diffusion, beam shaping, light splitting, and optical focusing, thereby achieving large viewing angle, low aberration, small distortion, high temporal resolution, and infinite depth of field. Meanwhile, it has important application potential in the form, intelligence and integration of op-to electronic devices and optical systems. In this paper, the optical principle and development history of lens arrays are introduced, and the lens array fabrication technologies such as ink jet printing, laser direct writing, screen printing, photo lithography, photo polymerization, hot melt reflow and chemical vapor deposition are reviewed. The application progress of lens arrays in imaging sensing, illumination light source, display and photovoltaic fields is presented. And this paper prospected the development direction of lens arrays, and discussed the development trends and future challenges of new directions such as curved lenses, superimposed compound eye systems, and the combination of lenses and new op-to electronic materials.

UVC Emission Devices Based on Alternating Current Inorganic Electroluminescence Using Y2SiO5:Pr3+ Phosphors

Ultraviolet C (UVC: 200-280 nm) lighting is urgently required for a number of sterilization applications such as water and air disinfection, food processing, and medical sterilization. Compared to other UVC emission sources, AC-driven inorganic phosphor electroluminescent (EL) devices are appealing due to their wide viewing angle, fast response time, low power consumption, high contrast, simple manufacture, and cost effectiveness. Although the luminance of inorganic phosphor EL devices is typically low, it is sufficient for most low-cost lighting and large-area display applications. In addition, inorganic phosphor EL devices have the advantage of emitting light without generating much heat. In this study, UVC emission was demonstrated through EL devices using a UVC phosphor. Pr3+-doped Y2SiO5 (Y2SiO5:Pr3+) is used for UVC light, Y2SiO5:Pr3+ phosphor shows a broad UVC emission at 280 nm from the f-d transition of Pr3+ ions as well as a sharp red emission at 610 nm from the f-f transition of Pr3+ ions. The phosphors were synthesized in three types to fabricate EL devices. The Y2SiO5:Pr3+ powder, film, and nano-powder formed the phosphor layers of EL devices by screen printing, spin coating, and electrophoretic deposition, respectively. In order to emit UVC light, patterned gold was used for transparent electrodes of the devices instead of conventional indium tin oxide (ITO), which absorbs the UV region. The EL devices were demonstrated in two types: powder EL and electrolyte EL. The fabricated EL devices showed a wide range of UVC emission from 260 nm to 330 nm. Finally, luminescent and electrical analysis of each device was performed to analyze the characteristics.

Preparation and improved luminescent properties of Tb3+/Yb3+ co-doped Na2O–CaO–SiO2–Al2O3–ZnO–CaF2 transparent glass-ceramics

Transparent glass-ceramics containing CaF2 single-phase or CaF2/Ca5(PO4)3F two-phase were obtained by heat-treating the precursor glass. Compared with the precursor glass, the glass-ceramics containing CaF2 crystal with low phonon energy greatly enhance the emission intensity. Further research was conducted on the influence of various crystallization procedures on the luminescent properties of the glass-ceramic, and the procedure crystallized at 660 °C for 4 h was determined to be the optimal heat treatment. The SEM results indicate that the crystal size of the glass-ceramics is in the nanometer scale, which guarantees the possibility of its optical application. The three-photon absorption process of the Tb3+/Yb3+ co-doped glass-ceramics containing CaF2 single-phase was confirmed based on the up-conversion emission spectra excited at different power of 980 nm laser. The chromaticity coordinates of the Tb3+/Yb3+ co-doped glass-ceramic are located in the green region, indicating its potential applications in green lighting and other optical display devices.

Parameter optimization method for light field 3D display

A parameter optimization method for light field three-dimensional (3D) display is proposed to improve the performance of integral imaging (InI) and super multi-view (SMV) display. The parameters of light field display are divided into system parameters and display parameters. The multi-objective genetic algorithm is used to optimize the system parameters so that the display parameters can reach the target values. The influence of all display parameters on the imaging quality of light field 3D display are comprehensively considered. When the weight of the depth of field (DOF) and field of view (FOV) are set to the maximum, the DOF and FOV are respectively improved compared with the original display parameters. By setting the weight of resolution to the maximum, the image quality of InI and SMV is improved by 32% and 21%, respectively.

Double hole transport layers deliver promising-performance in light-emitting diodes based on MAPbBr3 nanocrystals

Perovskite Nanocrystal Light Emitting Diodes (PNC-LEDs) are highly regarded as promising candidates for future solid-state lighting and high-definition display applications. To achieve high-performance LEDs, it is essential to have an emitting layer with a high photoluminescence quantum yield (PLQY) and excellent carrier transport properties, along with a well-optimized device structure. In this work, high performance MAPbBr3 NCs (PLQY>95 %) were synthesized via combination of 4-methoxyphenethylamine and didodecyldimethylammonium bromide, which lead to improved carrier transport of NC emitting layer. Moreover, a double hole transport layers (D-HTL) structure was developed to provide stepwise energy barrier for hole injection, resulting in improved external quantum efficiency (EQE). The green MAPbBr3 PNC-LED with the D-HTL structure exhibited a maximum EQE of 10.7 % and a current efficiency (CE) of 32.5 cd A−1, outperforming the PNC-LED with the conventional single HTL PTAA (EQE 5.8 %, and CE 17.7 cd A−1) by almost 2 times. These findings showcase a rational strategy to enhance PNC-LEDs performance through device structure engineering, particularly when utilizing a high-performance PNC emitting layer.