High Color Contrast Research Articles

Employing polyaniline/viologen complementarity to enhance coloration and charge dissipation in multicolor electrochromic display with wide modulation range

Multicolor electrochromic devices have gained attention widely. To support the development of multicolor electrochromic devices, we studied complementary combinations of a multicolor switchable polyaniline (PANI) electrode and 1-methyl-4,4′-bipyridyl iodide (MBI). In particular, MBI acting as an electrolyte and cathodic electrochromic layer can not only simplify the architecture of a device, but also support the color richness of the device simultaneously. Wide band optical modulation in visible light (58.1% at 550 nm) and near-infrared light (35% at 800 nm) confirms the advantageous optical properties of the combination, possessing a wide color gamut range over a range of working voltages adjustable for red, yellow, green, blue, and purple, each having a high color contrast of up to 73.8. This is accompanied by the excellent electrochemical performances of the mentioned combination, such as a fast response time of 1 s/1.9 s (modulating 77%-colored/bleached) with good cycle stability, and high coloration efficiency of 140.63 cm2/C. In addition, utilizing a screen-printed polyvinyl alcohol (PVA) as a masking barrier layer, it is possible to display patterned anti-counterfeit information within the application. Given these electrochromic performance properties, it is considered a readily feasible strategy to utilize PANI and MBI combination to develop novel electrochromic devices, which can be used widely in the areas of smart packaging, smart labels, and flexible smart windows associated with specific application scenarios.

Resonant-Cavity-Enhanced Electrochromic Materials and Devices.

With rapid advances in optoelectronics, electrochromic materials and devices have received tremendous attentions from both industry and academia for their strong potentials in wearable and portable electronics, displays/billboards, adaptive camouflage, tunable optics, and intelligent devices, etc. However, conventional electrochromic materials and devices typically present some serious limitations such as undesirable dull colors, and long switching time, hindering their deeper development. Optical resonators have been proven to be the most powerful platform for providing strong optical confinement and controllable lightmatter interactions. They generate locally enhanced electromagnetic near-fields that can convert small refractive index changes in electrochromic materials into high-contrast color variations, enabling multicolor or even panchromatic tuning of electrochromic materials. Here, resonant-cavity-enhanced electrochromic materials and devices, an advanced and emerging trend in electrochromics, are reviewed. In this review, w e will focus on the progress in multicolor electrochromic materials and devices based on different types of optical resonators and their advanced and emerging applications, including multichromatic displays, adaptive visible camouflage, visualized energy storage, and applications of multispectral tunability. Among these topics, principles of optical resonators, related materials/devices and multicolor electrochromic properties are comprehensively discussed and summarized. Finally, the challenges and prospects for resonant-cavity-enhanced electrochromic materials and devices are presented.

Electrochromism and Electrofluorochromism based on Viologen Derivative with 1,10‐Phenanthroline Moiety for Multicolor Large‐Area and Patterned Display

AbstractViologens, a typical group of electrochromic materials, show rich color changes under the external electrical stimulus. Recently, some of the viologen derivatives are reported to exhibit good luminescent performance. However, their luminescence colors are difficult to adjust owing to the strong electron‐accepting properties of viologens, which seriously hinders their applications in smart light‐emitting devices. In this work, the color/emission dual‐switchable viologen derivative Phen‐vio is designed and synthesized by introducing fluorophore 1,10‐phenanthroline into 4,4′‐bipyridine, for multicolor large‐area and patterned electrochromic/electrofluorochromic devices. Under voltage driving of −2.3 and −2.8 V, the devices exhibited reversible color and fluorescence color changes from light yellow to dark orange to dark blue, and from yellow to orange to green, respectively. Moreover, the devices displayed a high color contrast ratio of up to 77% at 600 nm. More importantly, the driving voltages of the devices do not vary with the change of the device area, which is huge application potential in smart windows and tags.

Exploring the attractiveness of combinations of natural colors and contemporary shapes in fashion design

In this research, the attractiveness of combinations of natural colors and contemporary shapes in fashion design is explored. This was done by means of a questionnaire survey. Four shapes of clothing and ten colors obtained from plant and insect pigments are proposed. The research was conducted in two phases – qualitative and quantitative analysis. The quantitative study confirmed the results of the qualitative study and using an appropriate data reduction method, the study results were analyzed graphically. The results showed that users rated designs with high-contrast color and shape combinations as more attractive than those with low-contrast combinations. The study also showed that in addition to the shape of the garment, the choice of natural color sources can also influence consumer preferences. This study aims to overcome the shortcomings of previous studies that only examined color without investigating its relationship to garment shape. The knowledge gained from this study can help fashion designers create garments that are both aesthetically pleasing and environmentally friendly. However, further research is needed to determine the relationship between natural colors, contemporary shapes and consumer behavior in selecting them.

A novel endoscopy image fusion system: combine white light imaging and compound band imaging.

White light imaging (WLI) is a commonly seen examination mode in endoscopy. The particular light in compound band imaging (CBI) can highlight delicate structures, such as capillaries and tiny structures on the mucosal surface. These two modes complement each other, and doctors switch between them manually to complete the examination. This paper proposes an endoscopy image fusion system to combine WLI and CBI. We add a real-time rotatable color wheel in the light source device of the AQ-200 endoscopy system to achieve rapid imaging of two modes at the same position of living tissue. The two images corresponding to the pixel level can avoid registration and lay the foundation for image fusion. We propose a multi-scale image fusion framework, which involves Laplacian pyramid (LP) and convolutional sparse representation (CSR) and strengthens the details in the fusion rule. Volunteer experiments and ex vivo pig stomach trials are conducted to verify the feasibility of our proposed system. We also conduct comparative experiments with other image fusion methods, evaluate the quality of the fused images, and verify the effectiveness of our fusion framework. The results show that our fused image has rich details, high color contrast, apparent structures, and clear lesion boundaries. An endoscopy image fusion system is proposed, which does not change the doctor's operation and makes the fusion of WLI and CBI optical staining technology a reality. We change the light source device of the endoscope, propose an image fusion framework, and verify the feasibility and effectiveness of our scheme. Our method fully integrates the advantages of WLI and CBI, which can help doctors make more accurate judgments than before. The endoscopy image fusion system is of great significance for improving the detection rate of early lesions and has broad application prospects.

Digital Display Preference of Electronic Gadgets for Visual Comfort: A Systematic Review.

Digital devices such as smartphones, tablets, computers, and laptops are used for various purposes. The digital display quality has been improved, making it less tiring and more favoured among users. This study aimed to review the visual comfort of digital devices and the preferences of digital display settings that enhance the visual comfort experienced by digital device users. A search of PubMed, EBSCO host MEDLINE Complete, Scopus database, Google Scholar, and manual citation review was conducted, covering the period between 2010 and 2022. The criteria were selected based on the PRISMA statements. The search mainly focused on finding the existing literature on digital devices that contribute to visual discomfort and digital device settings that provide better visual comfort. The database search resulted in 533 references via the application of Microsoft Excel. There were 28 studies included in the final assessment. Twelve studies accounted for digital devices that contributed to visual discomfort, while another sixteen studies for digital device settings provided better visual comfort. Digital displays with high luminance contrast, positive polarity and adequate colour were preferred for better visual comfort. Meanwhile, smaller fonts were preferred for desktops and laptops, while larger fonts were favoured for smartphones. This study provides insights for digital display developers to learn and improve their display technology to fit the preferences expressed.

NEW THIOPHENE BASED MATERIALS FOR EMISSIVE LAYERS OF ORGANIC LIGHT-EMITTING DIODES

Optoelectronic display devices have gained an important role in the modern world. Digital displays based on organic light-emitting diodes are taking one of the leading places among other displays due to high contrast and high-quality color gamut. The relative novelty of the technology is the reason for the insufficient number of researched materials for use in layers of organic light-emitting diodes. This paper analyzes the properties of molecular structures based on thiophene heterocycles, as well as the feasibility of their use for displays on exclusively organic light-emitting diodes and in complex technologies, such quantum dots color converter.
 Three thiophene structures of type T (thiophene), TB (thiophene-benzene), TPy (thiophene-pyrrole) were chosen for the study. Modeling and computing of characteristics of molecular structures was performed with the software for quantum chemical calculations Gaussian 09 due to the wide range of quantum chemical methods implemented in it, as well as high efficiency and convenient user interface.
 With the help of the selected software, modeling of molecules, optimization by B3LYP methods, and the values of HOMO and LUMO energy levels were calculated. Emission and absorption spectra of T, TB and TPy type structures were obtained. Based on the obtained results, the possible application of structures in the emitting layers of organic LEDs was determined. T-type molecules can be used as a material for creating a self-emitting layer for organic light-emitting diodes in the visible wavelength range. Molecules of the TB-type are suitable for creating devices with radiation in the ultraviolet range. Molecules of the TPy-type have no prospects for use in direct OLED radiation, but their characteristics allow us to propose these structures as sources of exciting radiation for the creation of devices with light color conversion technologies.

Accessibility and Age: Can Legibility Improve Opportunity to Process Advertising?

Inclusive design considers usability first: to design with the needs of everyone to decrease the mismatch between the end-user and the design object. In advertising, the mismatch may be in the opportunity to process an advertisement due to design strategies (i.e., executional ad cues). Based on the Motivation-Opportunity-Ability model of information processing, we focus on legibility as an important but underexplored encoding issue that can enhance consumers’ opportunity to process ads based on visual clarity and lead to perceptual fluency effects. Visual acuity declines with age, so legibility is particularly important for older adults and those with vision loss. In line with recommended accessibility guidelines, we manipulated two advertising design factors believed to impact legibility—color contrast and font style—in the supers of a video advertisement for a pharmaceutical drug and tested the communication outcomes (cognition, persuasion). Across three studies with three different-aged populations, we show that legibility was positively related to awareness of information in the supers and to positive perceptions of the advertisement. In line with accessibility guidelines, legibility was rated the highest for most people in the high-color contrast sans serif font supers. Implications for theory, accessibility and older people, and public policy are discussed.

Multi-Color States of High Contrast Nano Prussian Yellow Electrochromic Film

Aim: Construction of electrochromic device via Prussian yellow nanofilm on glass electrode. Background: Energy conservation is one of the primary research topics nowadays. Electrochromic devices with low power consumption and short stable switching periods are well suited to energyefficient applications, e.g., smart windows, car mirrors, displays, and electronic papers. Objective: Preparation of electrochromic Prussian yellow nanofilm on ITO glass by a simple chemical facile method and study of its electrochromic features. Methods: Prussian yellow nanofilm (iron (III) hexacyanoferrate (III)), was prepared by immersing the substrate in a solution of ferric nitrate and Potassium hexacyanoferrate. Prussian yellow nanofilm is characterized by ultraviolet-visible (Uv-Vis) spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Prussian yellow nanofilm shows an intense yellow color when it is in a pristine state. Results: Resultant Prussian yellow nanofilm underwent reversible redox reactions accompanied by color changes from Prussian yellow to Prussian green to further Prussian blue, then to Prussian white. The transmittance of Prussian yellow nanofilm varies from 21% for colored state at 450nm to 81 % (for fully bleached) at 0.9V. The contrast ratio and ratio of optical density to charge density were examined and the coloration efficiency was calculated to be 299.6 cm2C-1. Conclusion: Prussian yellow can be very simply prepared and used as an efficient, fast switching electrochromic device with high color contrast.

Designing vivid green Sr9Al6O18:Er3+ phosphor for information encryption and nUV excitable cool-white LED applications

Advanced forensic applications and optoelectronics both heavily rely on rare earth (RE) element activated luminous phosphor materials. We used latent fingerprints (LFPs) and white light-emitting diodes (w-LEDs) to detect Using an easy solution combustion technique, a single-phase green-emitting Sr9Al6O18:Er3+ (1–11 mol%) (SAO: Er) nanophosphor was created. The X-ray diffraction and Rietveld refinement were used to examine crystallographic data. The phosphors showed vivid-green luminescence when stimulated by 378 nm near ultraviolet (nUV). The concentration of Er3+ ions is observed to affect the photoluminescence emission (PLE) intensity, reaching its highest value at 5 mol% doping. The optimized phosphor is used in latent finger print (LFP), lip print (LP) and anti-counterfeiting (AC) applications. Under 378 nm excitation, multilevel features of the phosphor-attached LFPs could be clearly identified. The high colour contrast between the ridge and valley lines made for an excellent observation. We have developed simple brush and screen-printing methods for creating a variety of patterns using our custom anti-counterfeit security ink. In addition to this, the obtained AC tags exhibit high resolution and long-term durability. These characteristics clearly demonstrated that the current phosphor is an excellent luminescent material for data storage applications.

Effects of subjective perceptions of indoor visual environment on visual-related physical health of older people in residential care homes

Aging profoundly affects people's visual functions, and older persons generally show a declination of visual abilities. The indoor visual environment (IVE) in residential care homes (RCHs) is vital to ensure the visual-related physical health of older people (i.e., general vision, functional vision, visual acuity, physical discomfort, and injuries). The IVE, including opening design, interior design, and lighting conditions components, should be designed to satisfy older people's special visual needs. Hence, this study aims to investigate the effects of older people's subjective perceptions of the IVE on their visual-related physical health. In total, 197 questionnaires were collected from older persons living in RCHs. The integrated IVE–Visual-related Physical Health model was established based on multiple statistical methods for older residents in RCHs. The model revealed that the view out, window, corridors, furniture locations, curtains or louvers, handrails, and light level significantly affected the visual-related physical health of older people. Practical recommendations were proposed, including beds and seats near the windows with beautiful scenery, corridors with night lights and unblocked vision, automatic curtains with light sensors, handrails with a high color contrast with the background walls, minimum 200lx ambient lighting, etc. This study's findings provide valuable insight into enhancing the IVE in RCHs for older people's visual-related physical health.

Multiwalled carbon nanotubes with ethyl viologen diperchlorate in polyethylene oxide to develop an electrochromic device

The electrochromic device was fabricated using multiwalled carbon nanotubes along with ethyl viologen diperchlorate in polyethylene oxide. Doping of multiwalled carbon nanotubes in the electrolytic gel of the device exploits its electrical transport potential. A fusion of (inorganic–organic) finished tools indicates the most efficient colour switching with a minute bias and high colour contrast when switched to neon-blue coloured states. The electrical current–voltage characteristics of the device properly validates its operating mechanism. The fabricated device is having capability to switch over from a transparent to the neon blue coloured state in presence of a potential. A contrast neon blue colour of the device was observed at 1.9 V.

Pyrrole-based viologen derivatives with high contrast and magenta color for electrochromic-fluorescent devices

Pyrrole-based viologen derivatives with high contrast and magenta color for electrochromic-fluorescent devices

Screen Printed Reflective Electrochromic Displays for Paper and Other Opaque Substrates.

Paper electronics is a viable alternative to traditional electronics, leading to more sustainable electronics. Many challenges still require solutions before paper electronics become mainstream. Here, we present a solution to enable the manufacturing of reflective all-printed organic electrochromic displays (OECDs) on paper substrates; devices that are usually printed on transparent substrates, for example, plastics. In order to operate on opaque paper substrates, an architecture for reversely printed OECDs (rOECDs) is developed. In this architecture, the electrochromic layer is printed as the last functional layer and can therefore be viewed from the print side. Square shaped 1 cm2 rOECDs are successfully screen printed on paper, with a high manufacturing yield exceeding 99%, switching times <3 s and high color contrast (ΔE* > 27). Approximately 60% of the color is retained after 15 min in open-circuit mode. Compared to the conventional screen printed OECD architectures, the rOECDs recover approximately three times faster from storage in a dry environment, which is particularly important in systems where storage in low humidity atmosphere is required, for example, in many biosensing applications. Finally, a more complex rOECD with 9 individually addressable segments is successfully screen printed and demonstrated.

Multi-Color Light-Emitting Diodes

Multi-color light-emitting diodes (LEDs) with various advantages of color tunability, self-luminescence, wide viewing angles, high color contrast, low power consumption, and flexibility provide a wide range of applications including full-color display, augmented reality/virtual reality technology, and wearable healthcare systems. In this review, we introduce three main types of multi-color LEDs: the organic LED, colloidal quantum dots (CQDs) LED, and CQD–organic hybrid LED. Various strategies for realizing multi-color LEDs are discussed including red, green, and blue sub-pixel side-by-side arrangement; vertically stacked LED unit configuration; and stacked emitter layers in a single LED. Finally, according to their status and challenges, we present an outlook of multi-color devices. We hope this review can inspire researchers and make a contribution to the further improvement of multi-color LED technology.

Coupling Engineering of NH4 + Pre-Intercalation and Rich Oxygen Vacancies in Tunnel WO3 Toward Fast and Stable Rocking Chair Zinc-Ion Battery.

Herein, for the first time, a pre-intercalated non-metal ion (NH4 + ) with rich oxygen vacancies stabilized tunnel WO3 is proposed as a new intercalation anode to construct Zn-metal-free rocking-chair ZIBs. With the ethylene glycol additive in the aqueous electrolyte, the Zn2+ solvation structure can be regulated and the side reaction of hydrogen evolution can also be suppressed. Owing to the integrated synergetic modification, a high-rate and ultra-stable aqueous Zn-(NH4 )x WO3 battery can be constructed, which exhibits an improved specific capacity (153mAhg-1 at 0.1Ag-1 ), excellent rate performance (when the current density increases to 3Ag-1 , the specific capacitance is still 86mAhg-1 ), and a high cycle stability with 100% capacity retention after 2,200 cycles under 5Ag-1 . Ex situ X-ray diffraction and XPS reveal the reversible insertion/extraction of Zn2+ in (NH4 )x WO3 . The assembled (NH4 )x WO3 //MnO2 rocking-chair ZIBs delivers excellent capacity of 82mAhg-1 at 0.1Ag-1 , impressive cyclic stability. Additionally, the flexible (NH4 )x WO3 //MnO2 ZIBs can power the electrochromic device-based PANI/WO3 with high color contrast and fast response time. This study provides new insight for developing high-performance rechargeable aqueous ZIBs.

Time-resolved encryption via photochromic and mechanochromic system based on silane-substituted spiropyran

With the continuous progress of forgery and decryption, the traditional static encryption technology is becoming more and more inadequate, which also strongly demands the development of multilevel anti-counterfeiting materials and advanced multi-dimensional encryption strategies and technologies. Here a new strategy to realize time-resolved encryption based on a silane-substituted spiropyran is presented, which exhibits tunable dynamic photochromic features caused by the reversible photochromic and mechanochromic properties with exceptional reversible absorption/luminescence modulation ability both in powder and crystal state. This compound shows excellent photochromic properties, including extremely rapid response time, high contrast color change, high reversibility etc. In addition, the growth of large-size needle-like single crystal by solution evaporation is helpful to further explore the mechanism of grinding discoloration of the compound. What's more, it is possible to modulate the luminescence emission and color change by simply changing the ultraviolet light stimulation time or grinding time, providing fine and adjustable time-related characteristics for the material, which can not only be used for data processing with more extended information, but also be used to construct confidential materials by time-resolved multidimensional encryption and dynamic anti-counterfeiting.

Industrial Vision: Rectifying Millimeter-Level Edge Deviation in Industrial Internet of Things With Camera-Based Edge Device

Nowadays, to realize the intelligent manufacturing in Industrial Internet of Things (IIoT) scenarios, novel approaches in computer vision are in great demand to tackle the new challenges in IIoT environment. These approaches, which we call <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Industrial Vision</i> , are expected to offer customized solutions for intelligent manufacturing in an accurate, time efficient and robust manner. In this paper, we propose a novel approach to industrial vision, called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Edge-Eye</i> , to rectify the edge deviation automatically for Irradiated Cross-linked Polyethylene Foam (IXPE) production with millimeter-level accuracy. IXPE has been one of the most commonly used materials in industry. During the production process of IXPE sheets, their edges need keep aligned strictly, otherwise, they could quickly get out of the border of the rolling plate and cause the huge economic loss. We deploy a commercial camera with mobile edge node in front of the IXPE sheet to continuously detect and rectify the edge deviation. Particularly, to handle the complex production environment when extracting the edge of IXPE sheet, we deploy a pair of reference bars with high-contrast colors to efficiently differentiate the sheet edge from the background. Then, we propose a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bi-direction Edge Tracking method</i> to perform the edge detection from both vertical and horizontal aspects. To realize the rectification using mobile edge nodes with limited computing resources, we reduce the cost of computation by extracting the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Minimized Region of Interest</i> , i.e., the edge area overlapped with the higher contrast reference bar on both sides. We further design a negative feedback control system with multi-stage feedback regulation mechanism, keeping the edge deviation within <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">millimeter-level</i> . We implemented <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Edge-Eye</i> on the ARM64 platform and performed evaluation in the practical IXPE production process. The experimental results show that <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Edge-Eye</i> achieves the average accuracy of 5 mm for the edge deviation rectification, with the average latency of 200 ms for edge deviation detection. During the process of 20-month real deployment for 36 production lines, 66 manpower per day (90% of the overall manpower) has been saved, and the utilization rate of IXPE material increases from 87% to 94%.

Swift Photochromic Smart Window Based on Plasmonic Yolk‐Shell Nanophosphors

AbstractHerein, the fabrication of eccentric Ag@Void@Y2SiO5:Pr3+ plasmonic yolk‐shell nanophosphors (PYSNPs) with high up‐conversion efficiency, and their incorporation on photochromic WO3 layers, is demonstrated to fabricate photochromic smart windows with high coloration contrast and swift color change. The up‐conversion efficiency of the Pr3+ ion‐doped Y2SiO5 (Y2SiO5:Pr3+) nanoshells is enhanced by about 50% through the incorporation of carefully designed plasmonic Ag cores placed inside their hollow cavities. Introduction of these geometry‐optimized plasmonic nanophosphors at the surface of photochromic WO3 films results in about 24‐fold and tenfold enhancements of their coloration rate and kinetic constant, respectively. The strategy adopted for designing and fabricating the Ag@Void@Y2SiO5:Pr3+ PYSNPs and their subsequent incorporation in conventional photochromic films offers an exciting approach for fabricating photochromic smart windows with dynamically controlled transmission of solar radiation, which is a promising technology for reducing energy consumption associated with heating, ventilation, and air‐conditioning of buildings.

Rapidly Photocurable Solid-State Poly(ionic liquid) Ionogels For Thermally Robust and Flexible Electrochromic Devices.

Formation of ionogels through in situ polymerization can effectively improve electrolyte processability; however, the curing process has been slow and oxygen-sensitive. Considering the low oxygen solubility of poly(ionic liquid)s (PILs), in situ polymerized ionogels are designed to realize excellent electrolytes. Herein, two in situ polymerized ionogels (PIL A & PIL B) are formulated, and they can be rapidly photocured within a minute. The ionogels are highly transparent, stretchable, and exhibit excellent physicochemical stability, including thermal, electrochemical, and air stability, allowing them to perform in various conditions. Benefitting from these properties, two high-performance electrochromic devices (ECDs) are assembled, with iron-centered coordination polymer (FeCP) and tungsten oxide (P-WO3 ) electrochromic materials, achieving high color contrast (45.2% and 56.4%), fast response time (1.5/1.9 and 1.7/6.4 s), and excellent cycling endurance (>90% retention over 3000 cycles). Attributed to the thermal robustness of the ionogels, the ECDs can also be operated over a wide temperature range (-20 to 100 °C). With the use of deformable substrates (e.g., ultrathin ITO glass), curved electrochromic eye protector and flexible electrochromic displays are realized, highlighting their potential use in futuristic wearables.