Large Color Research Articles

Enhanced Hygrothermal Stability of In-Situ-Grown MAPbBr3 Nanocrystals in Polymer with Suppressed Desorption of Ligands.

Currently, the intrinsic instability of organic-inorganic hybrid perovskite nanocrystals (PNCs) at high temperature and high humidity still stands as a big barrier to hinder their potential applications in optoelectronic devices. Herein, we report the controllable in-situ-grown PNCs in polyvinylidene fluoride (PVDF) polymer with profoundly enhanced hygrothermal stability. It is found that the introduced tetradecylphosphonic acid (TDPA) ligand enables significantly improved binding to the surface of PNCs via a strong covalently coordinated P-O-Pb bond, as evidenced by density functional theory calculations and X-ray photoelectron spectroscopy analyses. Accordingly, such enhanced binding could not only make efficient passivation of the surface defects of PNCs but also enable the remarkably suppressed desorption of the ligand from the PNCs under high-temperature environments. Consequently, the photoluminescence quantum yield (PL QY) of the as-fabricated MAPbBr3-PNCs@PVDF film exhibits almost no decay after exposure to air at 333 K over 1800 h. Once the temperatures are increased from 293 to 353 K, their PL intensity can be kept as 88.6% of the initial value, much higher than that without the TDPA ligand (i.e., 42.4%). Moreover, their PL QY can be maintained above 50% over 1560 h (65 days) under harsh working conditions of 333 K and 90% humidity. As a proof of concept, the as-assembled white light-emitting diodes display a large color gamut of 125% National Television System Committee standard, suggesting their promising applications in backlight devices.

The role of color in transsaccadic object correspondence.

With each saccade, visual information is disrupted, and the visual system is tasked with establishing object correspondence between the presaccadic and postsaccadic representations of the saccade target. There is substantial evidence that the visual system consults spatiotemporal continuity when determining object correspondence across saccades. The evidence for surface feature continuity, however, is mixed. Surface features that are integral to the saccade target object's identity (e.g., shape and contrast polarity) are informative of object continuity, but features that may only imply the state of the object (e.g., orientation) are ignored. The present study tested whether color information is consulted to determine transsaccadic object continuity. We used two variations of the intrasaccadic target displacement task. In Experiments 1 and 2, participants reported the direction of the target displacement. In Experiments 3 and 4, they instead reported whether they detected any target movement. In all experiments, we manipulated the saccade target's continuity by removing it briefly (i.e., blanking) and by changing its color. We found that large color changes can disrupt stability and increase sensitivity to displacements for both direction and movement reports, although not as strongly as long blank durations (250 ms). Interestingly, even smaller color changes, but not blanking, reduced response biases. These results indicate that disrupting surface feature continuity may impact the process of transsaccadic object correspondence more strongly than spatiotemporal disruptions by both increasing the sensitivity and decreasing the response bias.

Increasing the Growth of Coelogyne rochussenii Orchid Plantlets by administering various concentrations of KH2PO4 and Pyridoxine

Coelogyne is a native Indonesian orchid with relatively large flower sizes and attractive colors. The purpose of this study was to determine the effect of giving concentrations of Potassium Dihydrogen Phosphate (KH2PO4) and Pyridoxine in Murashige And Skoog media on the growth of the Coelogyne Rochussenii De Vriese orchid subculture. The research was conducted at the UPT Tissue Culture Laboratory of Seeds of Food Crops, Horticulture, and Plantation, Riau Province, Jalan Kaharudin Nasution, Kelurahan Simpang Tiga, Kecamatan Bukit Raya, Kota Pekanbaru. The research was conducted for four months, from September to December 2022. The design used in this study was a factorial complete randomized design (CRD) consisting of 2 treatment levels, KH2PO4 and Pyridoxine, with three replications, KH2PO4:160 mgl, 170 mg/l), 180 mg/l), 190 mg/l, and Pyridoxine: 0 ppm 0.0 5 ppm, 0.10 ppm, 0.15 ppm. The results of the study by administering various concentrations of Potassium Dihydrogen Phosphate (KH2PO4) and Pyridoxine did not significantly affect all parameters observed in Murashige and Skoog media on the growth of the Coelogyne Rochussenii De Vriese orchid subculture.

Efficient large invisible color watermark embedding using conditional deep autoencoder model for medical applications

The widespread availability of the internet, in conjunction with very low-cost digital recording and storage devices, has ushered in an age in which the reproduction, illegal use, and malicious dissemination of digital information have become much more straightforward. Authentication of multimedia materials has garnered a lot of interest in recent days as a means of preventing illegal usage, theft, and misrepresentation of the content. Invisible watermarking tries to hide information in a medium in order to demonstrate ownership, integrity, or to hide a secret message. The goal of invisible watermarking is to hide the watermark and extract it without making it evident that the cover image is watermarked. This paper presents an invisible watermarking technique that can hide large color water marks in the cover media. The proposed model uses a Conditional Variational Autoencoder (CVAE) to encode the watermark into the cover image. The watermarked image is then decoded at the receiver to extract the watermark. Unlike the conventional watermarking techniques which hide a simple, small black and white image as watermark, the proposed model can embed large full color images as watermarks into the cover images. This makes the proposed model superior to the existing models by hiding large watermarks into the color images. The stego images produced a high PSNR greater than 40 for different watermarks and the images are visually indistinct from the original cover images.

A π-Bridge Spacer Embedded Electron Donor-Acceptor Polymer for Flexible Electrochromic Zn-Ion Batteries.

Zinc-ion batteries (ZIBs) have drawn much attention for next-generation energy storage for smart and wearable electronics due to their high theoretical gravimetric/volumetric energy capacities, safety from explosive hazards, and cost-effectiveness. However, current state-of-the-art ZIBs lack the energy capacity necessary to facilitate smart functionalities for intelligent electronics. In this work, a "π-bridge spacer"-embedded electron donor-acceptor polymer cathode combined with a Zn2+ -ion-conducting electrolyte is proposed for a smart and flexible ZIB to provide high electrochromic-electrochemical performances. The π-bridge spacer endows the polymeric skeleton with improved physical ion accessibility and sensitive charge transfer throughthe cycles, providing extremely stable cyclability with high specific capacity (110 mAhg-1 ) at very fast rates (8 Ag-1 ) and large coloration efficiency (79.8 cm2 C-1 ) under severe mechanical deformation over a long period. These results are markedly outstanding compared to the topological analogue without the π-bridge spacer (80 mAhg-1 at current density of 8 Ag-1 , 63.0 cm2 C-1 ). The design to incorporate a π-bridge spacer realizes notable electrochromism behaviors and high electrochemical performance, which sheds light on the rational development of multifunctional flexible-ZIBs with color visualization properties for widespread usage in powering smart electronics.

Synthesis of novel fluorobenzene-thiophene hybrid polymer for high-performance electrochromic devices

Electrochromic devices based on high-performance polymer materials with exceptional optical contrast, superior cycling stability, and large coloration efficiency are critical for the advancement of electrochromics, and have the potential to innovate a broad range of applications, including flexible displays and wearable electronics. Here, we design and synthesize three precursors of fluorobenzene-3-methylthiophene D-A-D type polymers through one-step Stille coupling, and then prepare the corresponding polymer films with good electrochemical and electrochromic properties via low-potential electropolymerization at 0.52 V vs Ag/AgCl. Interestingly, such polymers exhibit overall high electrochromic performances during the electrochemical reaction with inversible color changes between yellow and dark blue, including high optical contrast (83% at 1050 nm), fast response time (1.4 s / 0.8 s), and long-term stability (< 2% reduction after 250 cycles). As-fabricated electrochromic devices display excellent cycling stability (< 3% optical contrast degradation after 1,000 cycles) at a low drive voltage (0.8 V). Due to these excellent electrochromic properties, d-A-D type polymers based on fluorobenzene-3-methylthiophene can be further developed for practical applications such as near-infrared camouflage and E-displays.

An image style transfer algorithm based on attention mechanism and GhostNet

Image style transfer, which combines the content of one image with the style of another to create a new image, has many potential applications in the disciplines of image creation, creative style reproduction, animation production, and other areas. The majority of early image style transfer techniques used manual features. Due to advances in deep learning technology, the Generative Adversarial Network (GAN) method greatly increases the accuracy of image style transfer; however, when it comes to scenes with large color blocks, high resolution, or horizontal boundaries, their performance still falls short of practical application requirements. In this research, we present a GhostNet- and attention-based image style transfer technique. We specifically introduce the SELayer to learn and increase the weight value of each channel, which can improve the quality of style transfer and data processing capacity. In addition, GhostNet is included to accelerate image production even more. The findings of the experiments, both quantitative and qualitative, demonstrate that the suggested technique can enhance the impact of style transfer.

Preparation, characterization and electrochromic properties of amorphous Gd-doped TiO2 films

Titanium oxide has been widely studied in the field of electrochromism due to its unique color-changing behavior induced by ion insertion. In this paper, amorphous Gd-doped TiO2 films were synthesized via the RF magnetron reactive sputtering. The effects of Gd doping on the electrochromic performance of TiO2 films were explored in detail. The improved coloration efficiency of ∼60% at 540 nm for low Gd-doped TiO2 film (0.61%) is due to the formation of monoclinic Gd2O3 island nanostructure on the surface of TiO2, which enhances the reaction kinetics and charge capacity of the film. The wide optical modulation (73% at 650 nm), large coloration efficiency (59.7 cm2 C−1 at 650 nm) and short response time (coloring time is 16.9 s, bleaching time is 9.1 s) were obtained for the moderately Gd-doped TiO2 film (0.83%). However, for the high Gd-doped TiO2 films (≥1.0%), the coloration efficiency reduced, which is due to the excessive Gd2O3 hindered the electrolyte penetration into the TiO2 active material. By studying the effects of Gd doping on the electrochemical performance of TiO2, it can provide a valuable reference for determining the appropriate doping element and content for electrochromic materials.

Dual emission from donor-modified MR-TADF emitter: Evidence for coexistence of TICT and MR excited states

Multiresonance thermally activated delayed fluorescence (MR-TADF) materials have attracted wide attention due to their large radiation rate constant (kr) and high color purity. Attaching additional electron donor or acceptor was established as an effective strategy to optimize the optoelectronic parameters of MR-TADF emitters, such as the reverse intersystem crossing rate constant (kRISC). However, these is no report that both the MR and twisted intramolecular charge transfer (TICT) excited states can be detected simultaneously from a single molecule yet. Herein, a group of MR-TADF emitters BNCz-SAF, BNCz-DMAC and BNCz-PXZ are designed and synthesized through introducing different donor, spiroacridine (SAF), acridine (DMAC) and phenoxazine (PXZ), at the para-site of the boron atom of a famous MR core BNCz. All these three emitters maintained intrinsically excellent properties of MR-TADF molecules with high kr over 108 s−1 and high kRISC over 105 s−1. Interestingly, with gradually increasing the donor strength to PXZ, dual emissions from the MR core and the CT excited state between PXZ and BNCz moieties are detected simultaneously for BNCz-PXZ in either strong polar solvents or doped film in highly polar host, both of which are confirmed as the TADF with the lifetimes of about 4 μs. Independent of the host, the organic light-emitting diodes (OLEDs) of BNCz-SAF and BNCz-DMAC exhibited sky-blue electroluminescence with high external quantum efficiencies (EQEmax) of 25.3% and 23.8% and narrow full widths at half maximum (FWHM) of 23–25 nm. In contrast, BNCz-PXZ exhibited a single-band (482 nm) sky-blue EL in mCBP host with EQEmax of 20.9%, while exhibited dual-band EL at 484 and 548 nm from MR and CT states in higher polar host DPEPO, realizing a warm white emission with CIE (0.31, 0.48) and EQEmax of 16.4%. For the first time both the short-range CT (i.e. MR) and long-range CT (i.e. TICT) excited states are experimently detected and confirmed simultaneously from a donor-modified B,N-based polycyclic hydrocarbon skeleton, which may be a potential strategy to bulid up broad-spectra or white emission.

Detection of natural wood defects with large color differences based on branched network

Detection of natural wood defects with large color differences based on branched network

Porous WO3·2H2O film with large optical modulation and high coloration efficiency for electrochromic smart window

Porous WO3·2H2O film with large optical modulation and high coloration efficiency for electrochromic smart window

The enhancement of large photochromic coloration contrast with rapid responsive behavior in Ba3MgSi2O8:Dy3+ ceramics for instant information displays

Designing photochromic systems with information displays has been seldom studied but is critical to the realization of instant hand-writable system. Previous instant hand-writable systems with inorganic photochromic materials limited to low color contrast. Herein, by controlling the sintering environment and ion doping concentration, an excellent light response is achieved by engineering the formation of oxygen vacancy defects in Ba3MgSi2O8:0.25%Dy3+, the maximum color contrast as high as 80.7%. A hand-rewritable system fabricated using these photochromic materials exhibits excellent writing and erasing reversibility in response to UV illumination and thermal stimulus. In addition, a large luminescence modulation of 86.2% is achieved due to the well overlap between the emission peak of Dy3+ and the absorption peak of Ba3MgSi2O8. The resulting insights will be useful to researchers in inducing oxygen vacancy defects in high-performance inorganic photochromic systems for superior functional design.

Intraspecific floral colour variation in three Pedicularis species

Flower constancy describes the phenomenon that pollinators tend to successively visit flowers of a single species during foraging, reducing reproductive interference in natural communities. The extent of flower constancy is largely determined by the floral traits of co-flowering species. Both higher inter-specific and lower intraspecific differences of floral traits should contribute to a higher level of flower constancy. However, previous studies mainly focused on interspecific difference, and the intraspecific variation (consistency) of floral traits received much less attention. We hypothesise that selection may favour lower intraspecific floral trait variation in communities composed of multiple co-flowering congeners. We investigated the floral colour variation of three focal Pedicularis species that share pollinators in 19 communities composed of either single or multiple Pedicularis species. Colour was quantified using image-based colour analysis as perceived by pollinators. We found that most of the intrapopulation floral colour variation was below the colour discrimination threshold of bumblebees, implying strongly constrained by the visual selection by pollinators. Contrary to the hypothesis, there is no significant difference in intraspecific floral colour variation between different community contexts. It may be due to the relatively large interspecific floral colour differences of most co-flowering species. The influence of community context on intraspecific variation may be reflected in floral traits other than colours.

P‐15.2: Light Output Degradation of Full‐frame Projection Laser Displays

Laser display technology can be applied to laser TV, laser projector and other products. In different applications, laser sources have different quantity and packages of lasers. Laser display technology has the advantages of large color gamut, high brightness and low power consumption. One of the benefits of laser is the narrow spectral bandwidth. As a consequence, the display can have a very large color gamut. Affected by a number of factors, the light output of laser display could possibly change with the operation time. Some failure factors of optical elements composing full‐frame projection laser displays that contribute to the degradation of light output are summarized, and under controlled temperature and humidity conditions, the light output degradation of two groups of DUTs were tested.

1.1: Invited Paper: A novel scheme of projection film screen for ultra‐large color gamut with photonic band gap reflection mechanism

A novel scheme of projection film screen to get ultra large color gamut using photonic band gap reflection mechanism is proposed. The projection screen made by a kind of film that can only reflect three narrowband R/G/B light emitted from projector (E.g., 460nm, 560nm and 650nm), as well as absorb other visible light wavelengths. The film has a well‐designed nano level multilayer structure which can form three photonic band gaps to reflect 460nm, 560nm and 650nm light respectively. An ultra large color gamut of 73.44% Rec2020 (138.68% sRGB) was obtained even under a bright room ambient light, that makes projection image quality comparable to a traditional TV. It could be an effective way to help solve the problem of dull color performance shown on traditional projection screens.

Assessing profile uniformity of soils from weathered clastic sedimentary rocks in southwest China

The 41 pedons from weathered clastic sedimentary rocks were selected to assess the parent material and soil profile uniformity. The results can help to divide argillic horizon and identify the differences among the various soil profiles in soil quantitative classification. The Ti/Zr ratio and particle size distribution of soils were analyzed to quantitatively assess parent material uniformity. Next, the morphological characteristics, physical and chemical properties, generalizable horizon development indices and geochemical element characteristics of soils were analyzed to quantitatively assess soil profile uniformity. Finally, the coefficient of variation (CV) of soil properties were used as the input variables of the random forest model to assess soil profile uniformity. The results showed that the parent materials were all uniform in terms of geochemical elements, while 63% were assessed as exhibiting lithologic discontinuity in terms of particle size caused by different surface erosion force of slope water. In addition, 20% of the profiles showed large internal color differences, and the generalizable horizon development indices suddenly changed along the vertical direction. The physical and chemical properties and geochemical elements varied greatly in the principal component analysis grouped by parent material, being assessed as soil profile inhomogeneous due to complex abundant clastic sedimentary rocks and different slope terrain conditions. In the pedogenesis, the slope deposit and soil forming process can cause 85% of soils with lithologic discontinuity to exhibit soil profile uniformity. When assessing soil profile uniformity, the CVs of the clay-free particle size distribution were the best input variable of the random forest model, and it is most convenient to use the five indices of CVs of Al, Si/Al ratio, clay, total phosphorus and Na as the input variables.

Reddening-Free Q Parameters to Classify B-Type Stars with Emission Lines

The emission-line B-type stars constitute a heterogeneous group. Many of these stars show similar optical spectroscopic features and color indices, making it difficult to classify them adequately by means of photometric and spectroscopic techniques. Thus, it is relevant to deal with appropriate classification criteria to avoid as many selection effects as possible. For this purpose, we analyzed different reddening-free Q parameters, taking advantage of the Gaia and 2MASS photometric surveys, for both main sequence and emission-line B-type stars. Along with this work, we provided various criteria to search for normal and emission-line B-type stars, using different color–color, Q–color, and Q–Q diagrams. It was also possible to identify stars in different transition phases (i.e., (Rp−J) vs. (J−Ks) diagrams) and to classify them according to their NIR radiation excesses (i.e., the (Bp−Rp) vs. (H−Ks) diagram). Other diagrams, such as the QJKHK vs. (H−Ks) or QBpJHK vs. (Bp−Ks), were very useful to search for and classify different classes of B-type stars with emission lines. These diagrams highlighted the presence of several stars, classified as CBe, with large color excesses that seemed to be caused by the presence of dust in their envelopes. Therefore, these stars would be misclassified. Three groups of HAeBe stars with different intrinsic dust properties were also distinguished. The amount of intrinsic dust emission in the diverse groups of emission-line stars was well-recognized via the QJHK vs. QBpRpHK diagram. The different selection criteria are very important tools for automated designs of machine learning and optimal search algorithms.

Organolead Halide-Based Coordination Polymers: Intrinsic Stability and Photophysical Applications

ConspectusOrganolead halide-based photovoltaics are one of the state-of-the-art solar cell systems with efficiencies increasing to 25% over the past decade, ascribed to their high light-absorption coefficient, broad wavelength coverage, tunable band structure, and excellent carrier mobility. Indeed, these optical characteristics are highly demanding in photocatalysis and photoluminescence (PL), which also involve the solar energy utilization and charge transport. However, the vast majority of organolead halides are ionically bonded structures and susceptible to degradation upon high-polarity protic molecules (e.g., water (vapor) and alcohol), which are often inevitable in many photochemical applications. Encapsulation is a commonly used stabilization approach by coating protective layers, avoiding the direct contact between organolead halides and polar molecules. However, this may partially hinder the light penetration to the inner hybrid halide materials, and introduce new interface problems that are important in photocatalysis and luminescent sensing. Therefore, developing intrinsically stable organometal halide hybrids is a major target for their applications in optoelectronic applications.In this Account, recent research progress on the synthesis of organolead halide-based coordination polymers for a variety of photoactive applications is described. Herein, we propose a general strategy to advance the intrinsic stability of organometal halide crystalline materials by using coordinating anionic organic linkers, which occupy the excellent photophysical features analogous to those of perovskites. Unlike the organoammonium cations as for ionically bonded structures, the anionic structure-directing agents (e.g., organocarboxylates) render well-defined metal-carboxylate coordination motifs in extended architectures spanning from low-dimensional (0D, 1D) to high-dimensional cationic inorganic Pb-X-Pb (X = F-/Cl-/Br-/I-) sublattices. This family of organolead halide coordination polymers can endure chemically reactive environments over a wide range of pH and aqueous boiling condition, which have been systematically investigated by experimental studies and theoretical calculations. Many chloride/bromide-based coordination polymers show air-stable, broadband self-trapped emission with large Stokes shift and high color rendition, exhibiting the absolute quantum yields of 35-72%. Among them, the porous frameworks with low-dimensional (0D, 1D) inorganic blocks are recognized as a rare class of porous metal-organic frameworks (MOFs) constructed by lead halides as secondary building units (SBUs). They not only occupy substantially higher light-harvesting and carrier-transport properties than conventional metal oxide-based MOFs, but also allow for isoreticular modification to regulate the PL characteristics by guest molecules. More importantly, combining the high stability with excellent carrier characteristics, a layered organolead iodide coordination polymer shows the overall photocatalytic water splitting without the use of any sacrificial agent under simulated sunlight illumination. Given the wide choice of structurally diverse organocarboxylate linkers, we hope this Account provides deep insights on the importance of coordination chemistry in the discovery of a wide family of intrinsically stable organolead halides to expand their photophysical applications.

Flexible laterally-configured electrochromic supercapacitor with feasible patterned display

A flexible laterally-configured electrochromic supercapacitor was designed and fabricated through a fully-solution process. The laterally-configured transparent conductive electrode PEDOT:PSS-AgNWs/PET was prepared by spraying technology and then the magenta electrochromic polymer (PProDOT) and gel electrolyte were cast sequentially onto the laterally-configured electrode. The as-prepared device exhibits alternative color changes between magenta and transparent within the potential range −0.9 V and 0.9 V, and the electrochromic behavior is retained even if bent, proving its excellent flexible display properties. As expected, a “ZJUT” patterned flexible display device works clearly when applying driving potentials to the two circuits simultaneously. In addition, the asymmetric device (PProDOT||PEDOT:PSS) integrates excellent electrochromic and electrochemical energy storage properties in terms of high optical contrast of 59.5 %, large coloration efficiency of 423.5 cm2·C−1, fast switching time (7.4 s and 3.9 s), reasonable areal capacitance of 2.15 mF/cm2 at a current density of 0.05 mA/cm2 and robust cyclic stability which can retain 85.65 % and 77.42 % of its initial optical contrast and capacitance even after 1000 cycles of mechanical deformation. Hence, this work demonstrates the flexible laterally-configured electrochromic supercapacitor has great potential in the portable and wearable display fields, such as smart watches and electronic paper.

A study of preferred and natural memory colours across different ethnic groups

AbstractA psychophysical experiment was carried out to specify the preferred and natural memory colours corresponding to 24 familiar objects on mobile displays. These objects were selected to cover a large colour gamut in CIELAB space. One hundred and six observers from five different ethnic groups participated. Forty‐nine colours for each object were rendered three‐dimensionally to cover a large colour range. The results showed inter‐observer variations are small between different ethnic groups, about 1.4 and 1.3 CIEDE2000 colour difference units for naturalness and preference, respectively. Comparing the preference and the naturalness colour centres, the preferred colours are brighter and more colourful than naturalness colours, by 1 and 2 units in L* and C*ab attributes, respectively. Both sets of data show a great hue consistency. The results showed that different ethnic groups agreed well on the objects studied. It was found that the best‐agreed objects are strawberry, green apple, tomato, corn and purple grape, and the worst‐agreed objects are blueberry, broccoli, smurf, green pepper and blue sky.