Color Modulation Research Articles

Tunable Thermochromic Graphene Metamaterials with Iridescent Color.

Thermochromic materials have been widely applied in energy-efficient buildings, aerospace, textiles, and sensors. Conventional thermochromic materials rely on material phase or structure changes upon thermal stimuli, which only enable a few colors, greatly limiting their applicability. Here, we propose and demonstrate the concept of dynamically tunable thermochromic graphene metamaterials (TGMs), which can achieve continuous color tunability (380-800 nm) with fast (<100 ms) response times. The TGMs are composed of an ultrathin graphene oxide (GO) film on a flexible metal substrate. We demonstrated that external thermal energy can dynamically adjust the water contents in the GO film to manipulate the color of TGMs. An impressive thermochromic sensitivity of 1.11 nm/°C covering a large percentage of the color space has been achieved. Prototype applications for a cup and smartphone have been demonstrated. The reversible TGMs promise great potential for practical applications of temperature sensing in optoelectronic devices, environmental monitoring, and dynamic color modulation.

Color modulation of electrochromic nanosheet-structured nickel–cobalt oxide thin films

Color modulation of electrochromic nanosheet-structured nickel–cobalt oxide thin films

Colored electrolytes for electrochromic devices

Color tuning remains one of the main issues for electrochromic applications. Multicolored organic and inorganic electrochromic materials have been largely studied. Herein, a novel approach of color modulation is investigated: the electrolyte coloration. The color tuning is therefore not only due to electrochromic materials but addressed thanks to pigment addition in the electrolyte, which allows endless possibilities. A symmetrical PEDOT:PSS based display and a WO 3 //V 2 O 5 display were elaborated in order to characterize this coloration process. The PEGDMA/PEGMA copolymer gel electrolyte was processed by thermal polymerization using AIBN and colored using four different pigments. Similar switching times and capacities were measured from one colored electrolyte to another. This easy to set up method multiplies the achievable colors without altering electrochromic device stability. • Process of PEGDMA/PEGMA copolymer gel electrolyte by thermal polymerization using AIBN. • Pigments addition for electrolyte coloration. • Electrolyte coloration for color modulation in electrochromic devices.

Magnetic Structural Color Hydrogels for Patterned Photonic Crystals and Dynamic Camouflage

The development of programmable structural color hydrogels that can adapt to the variation of surrounding environments is of paramount importance for many important applications such as biosensing, information encryption, advanced anticounterfeiting, and adaptive camouflage. Herein, we report the design and fabrication of magnetic structural color hydrogels by introducing superparamagnetic core–shell Fe3O4@poly(4-styrenesulfonic acid-co-maleic acid) (PSSMA)@SiO2 nanoparticles into acrylamide and polyethylene glycol diacrylate hydrogels. The colloidal magnetic nanoparticles (MNPs) were able to self-organize into photonic crystals (PCs) under an external magnetic field, so that a variety of tunable structural color hydrogel patterns could be developed via magnetically induced self-assembly of colloidal MNPs and a subsequent mask-assisted UV polymerization of the pregel solution. Interestingly, the resulting hydrogels and PC patterns could swell in water, and the swelled hydrogels were able to shrink upon light irradiations, which resulted in the dynamic and reversible modulation of the structural color. As a proof-of-concept application, a chameleon-like structural color hydrogel was fabricated, and dynamic camouflage was demonstrated upon cyclic exposure to water and light irradiations. The research disclosed herein could shine a light on the development of advanced intelligent structural color hydrogels for diverse applications such as camouflage, anticounterfeiting, and beyond.

Performance evaluation of sputter-coating based color BIPV modules under the outdoor operational condition: A comparative analysis with a non-color BIPV module

Building integrated photovoltaic (BIPV) modules with color-cover glasses have been developed to overcome design limitations in building applications. Although several current studies have presented informative outcomes through experimental analysis, understanding the long-term operating performance of color BIPV modules is still insufficient, especially when considering the transmittance features of the color-cover glass. Therefore, this study evaluates the operational performance of color BIPV modules based on comparative analysis under outdoor experimental conditions. A typical BIPV module (i.e., a non-color BIPV module) and color BIPV modules are used for this comparative analysis. The transmittance characteristics of general low-iron tempered glass (LTG) and LTG with the color coating are considered to evaluate the effect of performance degradation according to the transmittance reduction by the color coating. The thickness differences of the coating layer make different color patterns of gray, blue, and orange. In addition, the color modules are installed on the inclined (30°) and the vertical (90°) plane to assess power performance on different angle positions. Compared to the ratio of transmittance reduction (RTR) by the color coating and the percentage of efficiency reduction (RER) by the color-cover glass, the RER is less than the RTR. The RER of operational efficiency for blue and orange modules is similar to the RER in STC. Still, the RER of the gray module’s operational efficiency is about 5% greater than RER in STC. , the voltage and current characteristics for the gray module using operational data are analyzed to investigate the effect of color differences on the power efficiency. Based on the result, it was confirmed that the active efficiency reduction of the gray module is expected from the decrease in the current.

Colour, Colour Modulation and Contextualization in NCDC Covid 19 Sensitization Posts: A Multi-Modal Socio Semiotic Approach

Colour, Colour Modulation and Contextualization in NCDC Covid 19 Sensitization Posts: A Multi-Modal Socio Semiotic Approach

MoS2 nano-flower incorporation for improving organic-organic solid state electrochromic device performance

A solid state electrochromic device has been fabricated using molybdenum disulfide (MoS2) doped Ethyl viologen (EV) and polythiophene (P3HT) layers. The MoS2 nano flower has been synthesized by one-step hydrothermal method and characterized by electron spectroscopy, X-ray diffraction and Raman spectroscopy. The prepared solid state electrochromic device shows its improved electrochromic performance like switching speed, cycle life and coloration efficiency while showing color modulation between magenta and blue colors. A very small external (±1.4 V) bias is sufficient to switch the device very quickly by taking time as low as 400 ms and shows the transmittance modulation of 42%. It is proposed that the MoS2 having graphene like 2D layered structure and the weak van der Waals force present between layers facilitates large amount of charge movement between the film and electrolyte, hence, promoting the high transfer rate of electrons, which plays the key role to enhance the performance of electrochromic device. Incorporation of MoS2 makes one of the most efficient devices in the family of polythiophene-viologen based devices and opened up a new avenues for other hybrid electrochromic device as graphene alternatives by exhibiting coloration efficiencies of as high as 580 cm2/C.

Dynamic Full‐Color Tuning of Organic Chromophore in a Multi‐Stimuli‐Responsive 2D Flexible MOF

AbstractDeveloping universal stimuli‐responsive materials capable of emitting a broad spectrum of colors is highly desirable. Herein, we deliberately grafted a conformation‐adaptable organic chromophore into the established coordination space of a flexible metal–organic framework (MOF). In terms of the coupled structural transformations and the space confinement, the chromophore in the MOF matrix underwent well‐regulated conformational changes under physical and chemical stimuli, simultaneously displaying thermo‐, piezo‐, and solvato‐fluoro‐chromism with color tunability over the visible range. Owing to the resilient nature and the reduced dimensionality of the selected coordination space, all three color modulations behaved in a sensitive and self‐reversible manner, each following a linear correlation of the emission maximum with stimulus. Single‐crystal X‐ray diffraction of the variable‐temperature structures and solvent‐inclusion crystals elucidated the intricate color varying mechanisms.

Dynamic Full-Color Tuning of Organic Chromophore in a Multi-Stimuli-Responsive 2D Flexible MOF.

Developing universal stimuli-responsive materials capable of emitting a broad spectrum of colors is highly desirable. Herein, we deliberately grafted a conformation-adaptable organic chromophore into the established coordination space of a flexible metal-organic framework (MOF). In terms of the coupled structural transformations and the space confinement, the chromophore in the MOF matrix underwent well-regulated conformational changes under physical and chemical stimuli, simultaneously displaying thermo-, piezo-, and solvato-fluoro-chromism with color tunability over the visible range. Owing to the resilient nature and the reduced dimensionality of the selected coordination space, all three color modulations behaved in a sensitive and self-reversible manner, each following a linear correlation of the emission maximum with stimulus. Single-crystal X-ray diffraction of the variable-temperature structures and solvent-inclusion crystals elucidated the intricate color varying mechanisms.

Tunable structural colors generated by hybrid Si3N4 and Al metasurfaces.

Metasurfaces with the capability of spectrum manipulation at subwavelength can generate structural colors. However, their practical applications in dynamic displays are limited because their optical performance is immutable after the fabrication of the metasurfaces. In this study, we demonstrate a color-tunable metasurface using numerical analysis. Moreover, we select a low-refractive-index dielectric material, Si3N4, which leaks the electric field to its surroundings. We investigate the potencial of these metasurfaces by simulations to achieve color-tuneable devices with encrypted watermarks. This modulation of colors can be applied to encrypted watermarks, anti-counterfeiting, and dynamic displays.

Tuning Exciton Coupling of Merocyanine Nucleoside Dimers by RNA, DNA and GNA Double Helix Conformations.

Exciton coupling between two or more chromophores in a specific environment is a key mechanism associated with color tuning and modulation of absorption energies. This concept is well exemplified by natural photosynthetic proteins, and can also be achieved in synthetic nucleic acid nanostructures. Here we report the coupling of barbituric acid merocyanine (BAM) nucleoside analogues and show that exciton coupling can be tuned by the double helix conformation. BAM is a nucleobase mimic that was incorporated in the phosphodiester backbone of RNA, DNA and GNA oligonucleotides. Duplexes with different backbone constitutions and geometries afforded different mutual dye arrangements, leading to distinct optical signatures due to competing modes of chromophore organization via electrostatic, dipolar, π–π‐stacking and hydrogen‐bonding interactions. The realized supramolecular motifs include hydrogen‐bonded BAM–adenine base pairs and antiparallel as well as rotationally stacked BAM dimer aggregates with distinct absorption, CD and fluorescence properties.

Tuning Exciton Coupling of Merocyanine Nucleoside Dimers by RNA, DNA and GNA Double Helix Conformations

AbstractExciton coupling between two or more chromophores in a specific environment is a key mechanism associated with color tuning and modulation of absorption energies. This concept is well exemplified by natural photosynthetic proteins, and can also be achieved in synthetic nucleic acid nanostructures. Here we report the coupling of barbituric acid merocyanine (BAM) nucleoside analogues and show that exciton coupling can be tuned by the double helix conformation. BAM is a nucleobase mimic that was incorporated in the phosphodiester backbone of RNA, DNA and GNA oligonucleotides. Duplexes with different backbone constitutions and geometries afforded different mutual dye arrangements, leading to distinct optical signatures due to competing modes of chromophore organization via electrostatic, dipolar, π–π‐stacking and hydrogen‐bonding interactions. The realized supramolecular motifs include hydrogen‐bonded BAM–adenine base pairs and antiparallel as well as rotationally stacked BAM dimer aggregates with distinct absorption, CD and fluorescence properties.

Improved Response of Upconversion Luminescence Color to Pump Power through the Coupling of Er3+ and Tm3+

Upconversion materials activated with Er3+ have been demonstrated to be potential candidates for multi-color displays, dynamic fluorescence anti-counterfeiting, and so forth. However, due to the similar upconversion pathways for green and red emissions, it remains a challenge to realize highly sensitive multi-color upconversion luminescence by adjusting the laser power. Here, based on Er2Mo4O15 without concentration quenching of luminescence, we demonstrated that the incorporation of heterogeneous Tm3+ impurities could significantly improve the response of luminescence color to laser power. Through solving a set of rate equations, it was clarified that the power-dependent depletion of the 4I11/2 level was responsible for the modulation of luminescence color. Also, it was proved that the enhancement of luminescence was in relation to the blocked energy migration and enhanced radiative transition probability. Our work provides an effective approach to improve the power response of luminescence colors based on the photon upconversion of Er3+.

Luminescence, energy transfer, colour modulation and up-conversion mechanisms of Yb3+, Tm3+ and Ho3+ co-doped Y6MoO12.

A series of novel up-conversion luminescent Yb3+/Ln3+ (Tm3+, Ho3+, Tm3+/Ho3+)-doped Y6MoO12 (YMO) nanocrystals were synthesized using the sol-gel method. The consistent spherical morphology of the nanocrystals with different doping ratios was found to be profiting from the homogenisation and rapid agglomeration of the composition in the gel state and calcining process. The X-ray diffraction (XRD) and field-emission scanning electron microscope images were employed to confirm perfect crystallinity and uniform morphology. Photoluminescence spectra and decay curves were used to characterize the optical properties of the synthesized samples. The YMO:Yb3+/Ln3+ (Tm3+, Ho3+, Tm3+/Ho3+) nanocrystals were excited by near-infrared photons and emitted photons distributed in blue, green, and red bands with a wide colour gamut, and even white colour, by optimising the relative doping concentrations of the activator ions. The energy conversion mechanism in the up-conversion process was studied using power-dependent luminescence and is depicted in the energy level diagram. In addition, 70% of the luminescence intensity of YMO can be preserved after annealing at 700 °C, and the temperature sensing was tested in the range 298-498 K. These merits of multicolour emissions in the visible region and good stability endow the as-prepared nanocrystals with potential applications in the fields of optical data storage, encryption, sensing, and other multifunctional photonic technologies.

Identification of three hub genes related to the prognosis of idiopathic pulmonary fibrosis using bioinformatics analysis.

Background: Idiopathic pulmonary fibrosis (IPF) is a chronic respiratory disease characterized by peripheral distribution of bilateral pulmonary fibrosis that is more pronounced at the base. IPF has a short median survival time and a poor prognosis. Therefore, it is necessary to identify effective prognostic indicators to guide the treatment of patients with IPF.Methods: We downloaded microarray data of bronchoalveolar lavage cells from the Gene Expression Omnibus (GEO), containing 176 IPF patients and 20 controls. The top 5,000 genes in the median absolute deviation were classified into different color modules using weighted gene co-expression network analysis (WGCNA), and the modules significantly associated with both survival time and survival status were identified as prognostic modules. We used Lasso Cox regression and multivariate Cox regression to search for hub genes related to prognosis from the differentially expressed genes (DEGs) in the prognostic modules and constructed a risk model and nomogram accordingly. Moreover, based on the risk model, we divided IPF patients into high-risk and low-risk groups to determine the biological functions and immune cell subtypes associated with the prognosis of IPF using gene set enrichment analysis and immune cell infiltration analysis.Results: A total of 153 DEGs located in the prognostic modules, three (TPST1, MRVI1, and TM4SF1) of which were eventually defined as prognostic hub genes. A risk model was constructed based on the expression levels of the three hub genes, and the accuracy of the model was evaluated using time-dependent receiver operating characteristic (ROC) curves. The areas under the curve for 1-, 2-, and 3-year survival rates were 0.862, 0.885, and 0.833, respectively. The results of enrichment analysis showed that inflammation and immune processes significantly affected the prognosis of patients with IPF. The degree of mast and natural killer (NK) cell infiltration also increases the prognostic risk of IPF.Conclusions: We identified three hub genes as independent molecular markers to predict the prognosis of patients with IPF and constructed a prognostic model that may be helpful in promoting therapeutic gains for IPF patients.

Photonic Crystal Palette of Binary Block Copolymer Blends for Full Visible Structural Color Encryption (Adv. Funct. Mater. 1/2022)

Block Copolymer Blends In article number 2103697, Cheolmin Park and co-workers develop a palette of block copolymer photonic crystal inks, enabling convenient modulation of the structural color in the full visible range via solution blending of two lamellar-forming block copolymers. The binary blend photonic crystals are applicable to various solution processes and offer efficient reflection-mode pattern encryption suitable for emerging vision encryption technology requiring ultra-thin, mechanically flexible, and thus skin-patchable performance.

Active modulation of reflective structural colors.

Dynamically controllable reflective structural colors have been garnering growing attention due to increasing commercial interests in smart displays (e.g., colorimetric labels), colored e-readers, etc. To comply with the requirements of future displays, several strategies have been proposed by various research groups to achieve wide color tuning ranges in the visible regime, high on/off contrast ratios, and fast response times. In this review, we first introduce ways to create optical resonances including plasmonic, photonic, and plasmonic-photonic hybrid structures that form the basis of color generation. We then outline strategies that control the refractive index contrast between the system and the surrounding as a means to actively change the reflective structural colors, backed with representative examples from the literature. Finally, we provide a comparison of dynamic structural colors based on various switching mechanisms summarizing performance metrics that are important for future displays, and conclude with an outlook on current challenges.

Reversible color modulation of luminescent conjugated polymers based on a chemical redox mechanism and applications in rewritable paper and multiple information encryption.

Reversible color modulation plays a key role in the field of information recording and encryption, but for the common colorful conjugated polymer materials, currently a convenient method to achieve their reversible color modulation is still lacking. Herein, six luminescent conjugated polymers P1 to P6 were successfully designed and synthesized, all of which could realize reversible color modulation through a similar reversible chemical redox behavior accompanied by reversible color and fluorescence changes. The same absorption spectral changes as those under electrochemical redox conditions strongly confirmed that these polymers underwent reversible redox reactions in the Fe3+ and H2O system, which happened spontaneously according to the theoretical analysis of the reaction thermodynamics. Based on the reversible color modulation in the Fe3+ and H2O system, polymers P1, P2 and P3, with different colors (yellow, orange and red) and fluorescence emissions, were successfully applied as rewritable paper with multi-color and multi-fluorescence printing as well as long-term recording capabilities. Meanwhile, polymers P1, P4, P5 and P6, which showed similar green fluorescence and yellow color but different oxidation potentials, were also introduced to accomplish multiple encryption and decryption of information, based on the step-by-step selective oxidation of the four polymers by adjusting the concentration of Fe3+.

Luminescence and energy transfer of color-tunable Tb3+/Sm3+co-doped BaZn2(PO4)2 glass-ceramic phosphors

The color-tunable phosphors can be obtained by co-doping strategy and energy transfer regulation. In this work, Tb3+ and Sm3+ co-doped BaZn2(PO4)2 glass-ceramic (GC) phosphors are prepared and their structural, optical and luminescent properties are characterized. By adjusting the doping concentration of Sm3+, The luminescent color of BaZn2(PO4)2 GC: Tb3+/Sm3+ Phosphors ranges from green to light green to yellow-green and finally to yellow. The photoluminescence (PL) spectra and fluorescence decay curves confirmed the energy transfer from Tb3+ to Sm3+, and the energy transfer efficiency (η) increased monotonically with the increase of Sm3+ concentration. Moreover, the energy transfer mechanism from Tb3+ to Sm3+ in BaZn2(PO4)2 GC is a dipole-dipole interaction. The typical BaZn2(PO4)2 GC: 0.75 Tb3+/0.75Sm3+ phosphor has a high thermal stability with an activation energy determined to be 0.29525 eV. Coupling BaZn2(PO4)2 GC: 0.75 Tb3+/0.75Sm3+ Phosphors with commercially available ultraviolet light-emitting diodes (UV-LEDs) chips yields luminescent color coordinates of (0.3965, 0.4253) and a color correlation temperature of 3927 K, close to warm white light emission. These results indicated that the Tb3+ and Sm3+ co-doped BaZn2(PO4)2 GC achieved luminescence color modulation, which has potential applications in UV-converted LEDs and other optical devices.

A Modular Design of Continuously Tunable Full Color Plasmonic Pixels with Broken Rotational Symmetry

AbstractColor tuning is a fascinating and indispensable property in various applications. Thus far, a variety of reconfigurable approaches have been implemented to achieve color change. However, it is still a challenge to enable continuous color tuning over the entire hue range in a simple, stable, and rapid manner without changes in configuration and material properties. Here, an all‐optical continuously tunable plasmonic pixel scheme is demonstrated via a modular design approach to realize polarization‐controlled full color tuning by breaking the intrinsic symmetry of the unit cell layout. The polarization‐controlled full color tunable plasmonic pixels consist of three different types of color modules corresponding to three subtractive primary colors. Without changing the structural properties or surrounding environment, the structural colors can be continuously and precisely tuned across all hues by illuminating linearly polarized light with different polarization directions. Meanwhile, the plasmonic pixels can be flexibly customized for various color tuning processes through the appropriate choice of component modules and the elaborate design of module layouts. Furthermore, the color tuning is extended to achromatic colors with the utilization of a single module or the introduction of a black module. The proposed plasmonic pixels hold considerable potential to function as next‐generation color pixels integrated with liquid‐crystal polarizers.