Full-color Display Research Articles

Static-spun mesoporous silica-coated CsPbBr3 blue fibres: synthesis and fluorescence properties.

Due to their excellent properties, blue CsPbBr3 quantum dots show great promise for full-colour display and lighting applications. This study used acetonitrile, a polar solvent, to post-treat CsPbBr3 quantum dots, resulting in a blue shift to 453nm. To enhance stability, these quantum dots were encapsulated within the pore structure of mesoporous silica. A flexible luminescent fiber material was prepared using poly (lactic acid) (PLA) as the substrate, demonstrating improved hydrophobicity and stable optical properties. The material exhibited a contact angle of 99.7° and maintained 82.2% of its fluorescence intensity after 30days at room temperature. These findings highlight its significant potential for optical applications.

Full-color electrophoretic display with high halftone image quality, reduced power, and deep-learning-enabled fast implementation

The electrophoretic display (EPD) with low power consumption, good sunlight readability, and flexibility is ideal for the Internet of Things. However, color EPDs have very limited grayscales (typically 1-bit) because it is challenging to precisely control the electrophoretic particles of multiple colors. Thus, halftone is usually employed to achieve continuous-tonal full-color EPDs alternatively. Nevertheless, halftone achieves continuous tones at the expense of a significant increase in driving current. This study first proposes and experimentally verifies a model that can accurately predict a driving current from image content. Next, a multi-objective optimized (MOO) halftone algorithm based on MOEA/D (multi-objective evolutionary algorithm based on decomposition) is proposed to consider image quality and driving current simultaneously. As a result, Pareto optimality is achieved, i.e., no image simultaneously performs better in image quality and driving current. A mean driving current reduction of 33.8% concerning the traditional error-diffusion algorithm is experimentally verified on a seven-color EPD with maintained halftone image quality. Considering the high computational complexity of the iteration-based MOO algorithm, this study also discusses the real-time generation of optimal halftone images using a generative adversarial network (GAN). Compared with the optimal halftone images slowly generated by the MOO, the GAN achieves almost the same driving current and a mean absolute error of 2.04, in terms of CIE76 color difference. The proposed algorithm enables full-color EPDs with high-quality continuous tones, reduced power consumption, and a GAN-based real-time implementation.

Recent Advances in Transfer Printing of Colloidal Quantum Dots for High-Resolution Full Color Displays

Recent Advances in Transfer Printing of Colloidal Quantum Dots for High-Resolution Full Color Displays

Polymer-stabilized cholesteric liquid crystals with multi-state reversibility for applications in advanced smart adjustable anti-counterfeiting and energy-saving displays

The creation of an anti-counterfeiting material with reflection color, fluorescence, infrared imaging, and electrical property information will increase the level of anti-counterfeiting. However, the creation of such a material has proved to be extremely challenging. In this study, twin anti-counterfeiting labels with intelligently tunable patterns were obtained through a strategy of PMMA loaded chiral molecules via diffusing on the micrometer scale. In order to enhance anti-counterfeiting ability, the multi-mode intelligently modulated advanced anti-counterfeiting material was obtained through the strategy of introducing photo-isomerizing dithienylethene and infrared-shielding Cs0.33WO3 nanoparticles. This material can be reversibly converted into fluorescent, reflected colors, infrared, and electrical characteristic signals. The encrypted information is displayed with red fluorescence under UV light irradiation. Furthermore, the encrypted information can be reversibly displayed and erased under repeated stimulation by voltage and pressure, heating and cooling, UV, visible and near infrared (NIR) light. The aim of our work is to create a simple method to prepare complex patterns of structural and fluorescent color anti-counterfeiting films with the improved anti-counterfeiting capability. Based on this, the strategy of co-doping fluorescent molecules and photochromic molecules in liquid crystals combined with etching technology has realized a multiple anti-counterfeiting mode with a higher level of security. The advanced multiple anti-counterfeiting mode can output encrypted information of multiple states which will greatly improve the level of anti-counterfeiting. In terms of display, we obtained billboards with complex patterns, price intelligently tunable and full-color display by diffusion S5011 in liquid crystals, thus extending their application in the field of electronic shelf labels.

Enhancing Quantum Dot Full-Color Display Performance Through Black Matrix Width Modulation

Enhancing Quantum Dot Full-Color Display Performance Through Black Matrix Width Modulation

Pure-Phase Perovskite Quantum Well for Green Light-Emitting Diodes.

Perovskite multiple quantum wells (MQWs) have shown great potential in the field of light-emitting diodes (LEDs). However, the random formation of QWs with varying well widths (n numbers) often leads to suboptimal interface defects and charge transport issues. Here, we reveal that the crystallization sequence of bromide-based perovskite MQWs is large-n QWs preceding small-n QWs. With this insight, we prevent the crystallization of subsequent small-n QWs by reducing the crystallization rate, ultimately resulting in the crystallization of only n = 5 QWs. This reduction in the crystallization rate is achieved through the chemical interaction of dual additives with perovskite constituents. Additionally, the chemical interaction effectively passivates the uncoordinated lead ions defects. Consequently, pure-phase perovskite QWs with a high photoluminescence quantum efficiency of 75% are achieved. The resulting green LEDs achieve a peak external quantum efficiency of 17.1% and a maximum luminance of 29,480 cd m-2, which is attractive for full-color display applications of perovskites.

High performance pixelated quantum dots array on Micro-LED by inkjet printing

Micro-LED display has risen to prominence in research and industry, distinguished by their numerous advantages. Quantum dots (QDs) film, serving as color conversion layers (CCLs) for Micro-LED, are considered a leading candidate for the next generation of displays, owing to their low power consumption and broad color gamut. Inkjet printing stands out as a feasible approach for crafting QDs CCLs. The essence of the process hinges on attaining a printed QDs film that boasts both uniformity and high-precision QDs array. However, the unstable printing of QDs ink significantly impacts the surface morphology of QDs arrays and the display performance of Micro-LEDs. Therefore, elucidating the mechanism behind the unstable printing of QDs in inkjet printing and fabricating QDs is of paramount importance. In this study, through the simulation of unstable printing with conventional QDs ink, we identified nozzle blockage and the rapid evaporation of low-boiling-point ink as the primary causes of unstable printing. This leads to aggregation and deposition of QDs, obstructing the nozzle and altering the fluid path. A novel binary organic composite ink was employed to print the QDs array on the substrate with ultra-stability, achieving a high yield and greatly reduced coffee-ring effect Micro-LED full-color display.

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).

Regulating ligand length to improve the PL QY and stability of CsPbCl0.9Br2.1 nanocrystals for LEDs and photoelectric applications

Perovskite luminescent materials have been extensively investigated due to their comprehensive applications for full-color display, lighting, and communication. However, the development of blue-emissive perovskites has seriously lagged behind that of green and red counterparts, primarily because of their low photoluminescence quantum yield (PL QY) and poor stability. Here, we prepared blue-emissive CsPbCl0.9Br2.1 perovskite nanocrystals (PeNCs) and enhanced their QY from 61.3 % to 90.4 % by regulating the chain lengths of ligands. Post-treated PeNCs also exhibit good stability, their PL intensity is maintained at about 90 % after storage at ambient conditions for 10 days. The exciton dynamics results obtained from time-resolved fluorescence spectra and transient absorption spectra show that dodecyldimethylammonium bromide (DDAB), featuring double 12-hydrocarbon chains, is more capable of passivating surface defects and inhibiting non-radiative composites than the other double 8- or double 16-carbon chain ligands, which greatly improved the probability and rate of radiative recombination. Subsequently, the mechanism of ligand chain length regulation on the PL properties and stability of PeNCs was analyzed in terms of ligand-NC surface interaction, ligand polarity, hydrophobicity, and spatial effects. Furthermore, the device based on DDAB-CsPbCl0.9Br2.1 demonstrated stable EL and long operation lifetime, indicating its significant potential as an efficient blue emitter for backlighting in display technologies.

Experimental investigation of high-speed WDM-visible light communication using blue, green, and red InGaN µLEDs.

Micro-light-emitting diodes (µLEDs) hold significant promise for applications in displays and visible light communication (VLC). This study substantiates the viability of a wavelength division multiplexing (WDM)-VLC system using InGaN blue, green, and red µLED devices. The devices exhibited notable color stability and high modulation bandwidth due to the weakly polarized electric field in the blue and green semipolar devices and the stress-optimized structure in the red device. The aggregated data rate reached 11.14 Gbps. Moreover, the blue, green, and red InGaN µLEDs exhibited a wide color gamut, encompassing 119.4% of the NTSC and 89.2% of the Rec. 2020 standards, affirming the potential of blue, green, and red InGaN µLEDs for applications in full-color display and WDM-VLC systems.

Photoluminescence and Electroluminescence Confocal Imaging of an OLED

In recent years organic light-emitting diodes (OLEDs) have become one of the leading technologies for full-colour display panels in high-end smartphones and televisions. This rapid growth in use has occurred because OLEDs offer an all-around superior performance to liquid crystal displays (LCDs). For example, they are thinner, lighter, more flexible, less power consumptive, and brighter.When new OLEDs are developed, the optoelectronic properties of individual components and the complete device can be characterised using photoluminescence (PL) and electroluminescence (EL) spectroscopy. In this poster presentation, we use a confocal Raman microscope to characterise and spatially resolve the optoelectronic properties of a fabricated OLED device with four imaging modalities: PL, EL, time-resolved PL (TRPL), and time-resolved EL (TREL). Using a confocal microscope to characterise an OLED's spectral and time-resolved properties provides much greater detail than bulk measurements. Figure 1

Ultrathin ring-shaped metasurface for a multiview 3D display

The development of glasses-free 3D multiview displays has opened up new avenues for experiencing 3D displays. Multiview technologies have the advantages of visual discomfort alleviation, smooth motion parallax, full-color display, and broad depth of focus. However, their intended uses are impeded due to the versatility of designing ultrathin display systems freely by using metasurface technology. This paper presents a technique for creating an ultrathin ring-shaped metasurface for a multiview display system with a thickness of 2 µm. The proposed multiview 3D display system generates eight views. Numerical simulations are used to confirm the efficacy of the suggested strategy, and the results demonstrate the attainment of a high-quality multiview 3D display. The proposed work demonstrates the potential applications of the metasurface in multiview display systems for electromagnetic wave manipulation in future 3D TVs, imaging, integrated optics, and next-generation compact displays.

Multiparticle Synergistic Electrophoretic Deposition Strategy for High-Efficiency and High-Resolution Displays.

Colloidal nanoparticles offer unique photoelectric properties, making them promising for functional applications. Multiparticle systems exhibit synergistic effects on the functional properties of their individual components. However, precisely controlled assembly of multiparticles to form patterned building blocks for solid-state devices remains challenging. Here, we demonstrate a versatile multiparticle synergistic electrophoretic deposition (EPD) strategy to achieve controlled assembly, high-efficiency, and high-resolution patterns. Through elaborate surface design and charge regulation of nanoparticles, we achieve precise control over the particle distribution (gradient or homogeneous structure) in multiparticle films using the EPD technique. The multiparticle system integrates silicon oxide and titanium oxide nanoparticles, synergistically enhancing the emission efficiency of quantum dots to a high level in the field. Furthermore, we demonstrate the superiority of our strategy to integrate multiparticle into large-area full-color display panels with a high resolution over 1000 pixels per inch. The results suggest great potential for developing multiparticle systems and expanding diverse functional applications.

Full-color time-sequential super multi-view near-eye display with front-lit waveguide illumination.

Light field (LF) displays can offer a quasi-natural three-dimensional (3D) viewing experience by tailoring the four-dimensional light information. However, the primary drawback of conventional LF displays is their limited image quality due to restricted information. To address this limitation, time-multiplexing techniques are employed, but the resulting system configurations are often impractical for achieving compact systems. Here, we present a compact time-sequential super multi-view LF near-eye display integrated with a front-lit, multi-directional illumination module for virtual reality application. This illumination module consists of an RGB light-emitting diode array and a waveguide, allowing us to exploit a high-speed reflective-type spatial light modulator and provide high-bit depth, full-color 3D scenes with quasi-continuous parallax in a compact form factor display. The prototype is implemented for a live demo and evaluated with both simulation and experiment. Our work provides a viable path towards the wide adoption of 3D virtual reality head-mounted displays.

Ultrahigh-fidelity full-color holographic display via color-aware optimization

Holographic display offers the capability to generate high-quality images with a wide color gamut since it is laser-driven. However, many existing holographic display techniques fail to fully exploit this potential, primarily due to the system’s imperfections. Such flaws often result in inaccurate color representation, and there is a lack of an efficient way to address this color accuracy issue. In this study, we develop a color-aware hologram optimization approach for color-accurate holographic displays. Our approach integrates both laser and camera into the hologram optimization loop, enabling dynamic optimization of the laser’s output color and the acquisition of physically captured feedback. Moreover, we improve the efficiency of the color-aware optimization process for holographic video displays. We introduce a cascade optimization strategy, which leverages the redundant neighbor hologram information to accelerate the iterative process. We evaluate our method through both simulation and optical experiments, demonstrating the superiority in terms of image quality, color accuracy, and hologram optimization speed compared to previous algorithms. Our approach verifies a promising way to realize a high-fidelity image in the holographic display, which provides a new direction toward the practical holographic display.

Hollow Cylindrical Micro-LEDs: Enabling High-Brightness Quantum Dots-Based Color Conversion for Full-Color Displays

Hollow Cylindrical Micro-LEDs: Enabling High-Brightness Quantum Dots-Based Color Conversion for Full-Color Displays

Phosphonic Chloride Assisted Fabrication of Highly Emissive Mixed Halide Perovskite Films in Ambient Air for Blue Light-Emitting Diodes.

Blue perovskite light-emitting diodes (LEDs) have emerged as promising candidates for full-color display and lighting applications. However, the fabrication of blue-emitting perovskite films typically requires an inert environment, leading to increased complexity and cost in the manufacturing process, which is undesirable for applications of perovskite LEDs. Herein, we report a strategy to fabricate bright blue-emitting perovskite films in ambient air by incorporating phosphonic chlorides in a perovskite precursor solution. We used two different phosphonic chlorides, diphenylphosphonic chloride (DPPC) and phenylphosphonic dichloride (PPDC), and comparatively studied their effects on the properties of perovskite films and the blue LEDs. It is found that PPDC possesses a stronger chlorination ability due to higher hydrolysis reactivity; meanwhile, it has a stronger interaction with the perovskite compared to DPPC, resulting in an improved film quality and enhanced blue emission with a photoluminescence quantum yield of 45%, which represents the record value for the air-processed blue perovskite films. Blue perovskite LEDs are fabricated, and the emission wavelengths are effectively tuned by controlling the concentration of phosphonic chlorides. Benefiting from the optimized perovskite films with reduced nonradiative recombination and promoted charge injection and transport, the PPDC-derived blue perovskite LEDs exhibit improved performance with an external quantum efficiency of 3.3% and 1.2% for the 490 and 480 nm emission wavelength, respectively.

Electrohydrodynamic Inkjet Printing of Three-Dimensional Perovskite Nanocrystal Arrays for Full-Color Micro-LED Displays.

Perovskite nanocrystal (PeNC) arrays are showing a promising future in the next generation of micro-light-emitting-diode (micro-LED) displays due to the narrow emission linewidth and adjustable peak wavelength. Electrohydrodynamic (EHD) inkjet printing, with merits of high resolution, uniformity, versatility, and cost-effectiveness, is among the competent candidates for constructing PeNC arrays. However, the fabrication of red light-emitting CsPbBrxI(3-x) nanocrystal arrays for micro-LED displays still faces challenges, such as low brightness and poor stability. This work proposes a design for a red PeNC colloidal ink that is specialized for the EHD inkjet printing of three-dimensional PeNC arrays with enhanced luminescence and stability as well as being adaptable to both rigid and flexible substrates. Made of a mixture of PeNCs, polymer polystyrene (PS), and a nonpolar xylene solvent, the PeNC colloidal ink enables precise control of array sizes and shapes, which facilitates on-demand micropillar construction. Additionally, the inclusion of PS significantly increases the brightness and environmental stability. By adopting this ink, the EHD printer successfully fabricated full-color 3D PeNC arrays with a spatial resolution over 2500 ppi. It shows the potential of the EHD inkjet printing strategy for high-resolution and robust PeNC color conversion layers for micro-LED displays.

Color spherical holographic display system based on conformal diffraction principle

The ideal spherical holographic display promises an expanded field of view, which allows for observation from all angles. However, challenges still exist in the spherical holographic display, primarily stemming from the planar modulator and the holographic distortion. Here, a color spherical holographic display system based on conformal diffraction principle is proposed. The core components of the system include a color laser and a spatial light modulator loaded with spherical holograms. A synchronous sequential controller is developed to achieve color dynamic holographic display. Furthermore, the conformal diffraction principle is proposed to generate distortion-free holograms. Based on the principle, the recorded object is characterized as a conformal spherical object, and a precise correspondence between the hologram and the spherical reconstructed image is established. By leveraging the proposed system, the full-color high-quality spherical holographic display with expanded viewing angles can be realized, which can flexibly adapt to different holographic display scenes. The proposed system advocates the application of spherical holographic display and has potential applications in several fields.

Energy-efficient dispersion compensation for digital micromirror device

Due to the wave nature of light, the diffraction pattern generated by an optical device is sensitive to the shift of wavelength. This fact significantly compromises the digital micromirror device (DMD) in applications, such as full-color holographic display and multi-color fluorescence microscopy. The existing dispersion compensation techniques for DMD involve adding diffractive elements, which causes a large amount of waste of optical energy. Here, we propose an energy-efficient dispersion compensation method, based on a dispersive prism, for DMD. This method simulates the diffraction pattern of the optical fields reflected from the DMD with an angular spectrum model. According to the simulation, a prism and a set of optical components are introduced to compensate for the angular dispersion of DMD-modulated optical fields. In the experiment, our method reduced the angular dispersion, between the 532 nm and 660 nm light beams, by a factor of ∼8.5.