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Nanostructured CuS films were synthesized on FTO substrates employing low-cost electro deposition technique. XRD, Raman, SEM, UV–visible spectroscopy, photocurrent, PL, Mott-Schottky, and electrochemical impedance spectroscopy (EIS) measurements were used to examine physical and photoelectrochemical properties of samples. XRD results indicated that CuS films have hexagonal crystal structure where the crystallite size raises from 32 to 53 nm with increasing the Cu2+ molarity. Raman results displayed two peaks at 270 and 450 cm−1 that related to A1g transverse optical mode (TO) and A1g longitudinal optical (LO) mode for the vibrations of the S–S stretching and Cu–S bonds, respectively. SEM images displayed that fabricated CuS cover the substrate surface entirely, where grains are distributed uniformly with increasing the Cu+2 molarity. UV–visible measurements exhibited an absorption band edge between 450 and 550 nm as a characteristic of CuS films direct band gap. PL results presented strong blue-green emission at about 500 nm for CuS thin films. The photocurrent studies demonstrated that the CuS films are p-type semiconductors where the current density increases from 0.8 mA/cm2 to 1.1 mA/cm2 with the Cu2+ molarity increasing. The EIS analysis confirmed that charge transfer resistance reduces with increasing molarity. Mott- Schottky measurements established that carrier concentrations and the flat band varied from 5 × 1019 to 6.7 × 1019 cm−3 and from 1.1 to 0.75V, respectively. The fabricated CuS film was tested as glucose biosensor where a fast response and higher stability were noticed. Our results indicated that nanostructured CuS films are gifted candidates for optoelectronics applications especially biosensors. [ABSTRACT FROM AUTHOR]

Multi-stimuli responsive polycyclic aromatic hydrocarbons offer advantages of high selectivity, sensitivity, and versatility as they can integrate multiple inputs and outputs to achieve the desired applications in a flexible manner. In this context, carbazole and its derivatives have been extensively studied due to their tunability, outstanding electrochemical properties and good environmental stability. However, most of the studies used the polymeric forms of carbazole derivatives which requires energy-intensive synthesis. Recently, it has been reported that the self-assembled monolayers of carbazole derivatives offer more advantages over their polymeric forms in terms of stability and efficiency. Herein, we introduce a carbazole-based low molecular weight gelator achieved with synthetic ease, exhibiting a multi-stimuli response behaviour, i.e. sensing of cyanide ions and electrochromism, in its solution state. Further, the compound forms a gel in dioxane–H2O and DMF–H2O mixtures and exhibits aggregation-induced emission (AIE). The mechanistic pathways of sensing have been investigated and the limit of detection is found to be 1.25 nM, which is significantly lower than the permissible limit established by the WHO. Furthermore, possibilities of extending the electrochromism and sensing in the gel state using carbazole derivatives have been explored and the results indicate that low molecular weight carbazole derivatives are promising candidates for electrochromism and sensing applications. [ABSTRACT FROM AUTHOR]

Amorphous tungsten oxide (WO3) is widely exploited in the fields of photochromism and electrochromism. Despite its widespread use, the tractable synthesis of amorphous WO3 nanodots is still on the drawing board, even though the WO3 nanodots possess superior chromatic performance owing to their large surface‐to‐volume ratio. Therefore, a new efficient strategy to synthesize amorphous WO3 nanodots, which exhibit both excellent electrochromic and photochromic properties, is reported. For the first time, the ligand effects of the amorphous WO3 nanodots on chromatic applications are elucidated. The presence of the ligand on amorphous WO3 nanodots inhibits the electrochromic color switching, while promoting photochromic performance. As a proof of concept, zinc‐WO3 electrochromic devices, WO3‐polyvinyl alcohol (PVA) transparent hydrogels, and PVA/WO3 textiles are prepared for diverse rapid‐switching chromatic applications. These results present a new strategy for the synthesis of widely used amorphous WO3 nanodots and open new opportunities for the development of WO3‐based chromatic applications. [ABSTRACT FROM AUTHOR]

A series of anodically coloring electrochromic molecules comprised of thioalkyl‐substituted 3,4‐ethylenedioxythiophenes coupled to triphenylamine units that vary in position and degree of electron rich character of the substituents are reported, which influences the molecules geometric, electrochemical, optoelectronic, and excited‐state properties. Their redox properties are evaluated and it is discovered that modulation of both the first and second oxidation potential, formation of the cation radical, and dication respectively, can be varied from 0.03 to 0.18 V and 0.32 to 0.46 V versus Fc/Fc+ respectively. For the first time in ACE‐based molecular systems, the ability to vary the electrochemical potential separation between successive charge states is demonstrated, which directly influences the generation of color. The chemical oxidant, ferric triflate, is used to visualize the vibrantly colored cation radical solutions at 1 equivalent, followed by a second equivalent that opens a new and differing color palette for the dication state. Optical transitions are probed during electrochemical oxidation using an optically transparent thin layer electrode demonstrating selective control in generating successive charge states. Density functional theory simulations are used to analyze the excited state and elucidate how substituent identity affects the neutral, cation radical, and dication optical transitions, and thereby the resulting color. [ABSTRACT FROM AUTHOR]

The red V2O5 sol was prepared by facile alternating stirring and ultrasonic dispersion route. A V2O5 film fabricated on ITO-PET by electrophoresis method was used to demonstrate a flexible electrochromic device. The effects of applied voltage and electrophoresis time for V2O5films were investigated in detail. When the electrophoresis time was kept 30 s, the applied voltage was above 3 V to deposit uniform V2O5-PET film. The electrophoresis time could more significantly regulate the deposition of V2O5 on ITO-PET film. A flexible electrochromic device with "sandwich" structure was fabricated using V2O5 film, and its electrochromic performance of the device was evaluated. The flexible V2O5 electrochromic devices show the multicolor electrochromic performance of yellow, yellow-green, green and orange-red. The coloration efficiency values of V2O5 devices were 21.6 cm2C − 1 (from initial yellow to green) and 26.9 cm2C − 1 (from green to orange-red), respectively, and the highest transmittance modulation range was 51% at 741 nm. The work provided a facile and green method for fabrication of flexible V2O5 electrochromic device. [ABSTRACT FROM AUTHOR]

In order to study the effect of the substrate temperature on the electrochromic properties of NiOx film, DC reaction magnetron sputtering method was used to prepare NiOx film at different substrate temperatures, i. e, room temperature, 50, 100, 200 and 300 °C. The properties of the films including structure and morphology, cyclic stability, optical modulation rate, memory effect, response time, and adhesion to the substrate were explored and compared. The results show that the effect of the substrate temperature on the electrochromic properties of NiOx film is complicated. NiOx film prepared at 100 °C shows low charge capacity density decay rate, good memory effect, fast response speed, high modulation rate and good adhesion to the substrate. This study may have certain reference significance for the design and fabrication of NiOx-based electrochromic devices. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI), a polymer material exhibiting exceptional electrical conductivity, has garnered widespread application in electrochromic devices and supercapacitors. While PANI effectively demonstrates an electrochromic effect within the visible light band (400-780 nm), its adjustability in the near-infrared band (above 780 nm) remains limited. Consequently, its temperature control capabilities require enhancement. To address this, tungsten oxide dihydrate (WO3· 2H2O), a cathode discoloration material, was integrated with PANI to bolster its ability to regulate light transmittance in the near-infrared band. In this study, the WO3·2H2O@PANI composite film was fabricated utilizing the spin-coating method, and its surface morphology and electrochromic properties were thoroughly examined. Our findings reveal that the electrochromic performance of the WO3·2H2O@PANI composite film has been significantly improved in the near-infrared band. Furthermore, it exhibits a stronger bonding force with the ITO glass surface, thereby enhancing both its electrochemical and optical stability. [ABSTRACT FROM AUTHOR]

Multicolor electrochromics have emerged as a promising solution for achieving active color modulation akin to chameleon‐like adaptive camouflage. However, the development of electrochromics with full‐color tunability still remains challenging, given the weak molecular polarity of inherent active materials and the difficulty in forming polarizer orbitals under varying applied voltages. Employing molecular polarity adjustments, a novel electrochromic polymer is successfully developed with a donor‐gradient design of molecular architecture, enabling comprehensive full‐color tunability. The polymer demonstrates outstanding overall electrochromic performance, including fast switching (around 1.4 s), high coloration efficiency (395.1 cm2 C−1@550 nm) and excellent reversibility (over 92% retention after 5000 cycles). Leveraging the full‐color tunability and rapid response, the electrochromic polymer is further integrated with sensing and control modules to create an environmental adaptive camouflage prototype system capable of seamlessly blending colors with dynamic background environments. This work is expected to provide a straightforward approach for developing full‐color electrochromics for electrochromic camouflage applications. [ABSTRACT FROM AUTHOR]

With the rapid development and wide application of visible (VIS) and infrared (IR) detections, it is necessary to explore visible-infrared (VIS-IR) compatible camouflage. Here, we report a VIS-IR compatible and independent camouflage device which is composed of the upper IR-transparent VIS-color-patterned layer and the lower electrochromic IR layer. The upper layer has amorphous photonic structure of polystyrene nanospheres (PSNSs). By customizing the PSNS size, various colors can be realized for VIS camouflage. The lower electrochromic IR layer takes advantage of multiwall carbon nanotubes (MWCNTs) as the electrode as well as the IR active material. Experimental results reveal that different colors (including blue, green, and purple) have been obtained, and the IR emissivity can be electrically regulated from 0.43 to 0.9. Moreover, the prototype also exhibits good electrical stability as well as hydrophobic characteristic (the water contact angle of the outmost surface exceeds 120°). These output performances demonstrate the success of our design strategy for promoting the finding applied in camouflage fields as well as energy conservation fields. [ABSTRACT FROM AUTHOR]

Electrochromic (EC) smart windows are an elegant alternative to dusty curtains, blinds, and traditional dimming devices. The EC energy storage smart windows and displays received remarkable attention in the optoelectronic industry as they hold promise for high energy efficiency, low power consumption, reversibility, and swift response to stimuli. However, achieving these properties remains challenging. Moreover, most EC molecules do not exhibit electrofluorochromism, which is highly essential for smart displays because its EC property can modulate the solar heat entering the building, and its electrofluorochromic (EFC) aspects can create lighting during the night. In this work, a structure‐property relationship is utilized to develop new electrochromes that can store the injected charge, and these molecules indeed exhibit electrofluorochromism. The compounds are synthesized from tetrabenzofluorene with two aromatic acceptor units, and avoids the use of widely studied heterocycles and amine derivatives. The electrochromes switches from yellow to dark hue in solution, solid, and gel state. The compounds display exceptional electrochemical stability and reversibility in 1000 cycles and capacity retention of 93–100 % in 300 charging‐discharging cycles. The proof‐of‐concept device fabrication of the self‐dimming EC smart window presented here demonstrates that it can furnish visual comfort, modulate transmitted light and glare, and reduce energy usage. [ABSTRACT FROM AUTHOR]

Coloration in oxides meets the challenge in achieving high stability and repeatability simultaneously. In this work, reversible coloration of TiO2 nanoparticles (NPs) film is demonstrated by alternate ultrafast (UF) laser and continuous wave (CW) laser irradiation. Under UF laser irradiation, oxygen vacancies are introduced in the TiO2 lattice, which lead to the bandgap reduction (2.73 to 1.50 eV) and surface blackening. The blackened area can achieve high resolution with size down to ≈1.1 µm. This coloration in TiO2 also shows excellent thermal stability that color fading is negligible even after thermal annealing at 700 K for 2 h in air. The generated high temperature by CW irradiation is known to be beneficial for the O2 dissociation on defected TiO2, thus promoting the internal oxygen diffusion to eliminate the vacancies. The energy band structure of TiO2 can be recovered accordingly, and decoloration is achieved. TiO2‐NPs film shows stable microstructures with barely changed optical properties after 12 cycles of coloration–decoloration process. This band engineering‐induced reversible coloration can also be applicable for broad oxides, e.g., ZnO, HfO2, and Ga2O3. Such highly stable and reversible coloration is promising in high‐performance micro/nano‐devices development for color display and optical encryption. [ABSTRACT FROM AUTHOR]

A series of sulfur‐bridged 2,2′‐viologens, 2,2′‐thienoviologens (2,2′‐SV2+) with propyl bridge and hydroxyl bridges, are synthesized for the first time. The 2,2′‐thienoviologens exhibited improved visible‐light absorption, narrow energy gap, more negative reduction potential (160 mV lower than 4,4′‐thienoviologens) and more stable free radical states compared with 4,4′‐thienoviologens and parent 2,2′‐viologens. The utilization of femtosecond transient absorption (fs‐TA) demonstrated that 2,2′‐thienoviologen can produce distinct charge‐separated states under visible light excitation. Due to their excellent photophysical and electrochemical properties, the 2,2′‐thienoviologens are used for electrochromic devices and combined with g‐C3N4 via hydrogen bonds for visible‐light catalytic production. Based on the advantageous electron‐donating properties of 2,2′‐SV2+, the hydrogen release efficiency of the 2,2′‐thienoviologens‐modified composites is 8542 µmol·h−1·g−1, a value that is the highest reported for hydrogen production from organic small‐molecule‐modified g‐C3N4 and 78 times higher than that of unmodified g‐C3N4. This study presents a concise method to convert solar energy and broaden the potential applications of 2,2′‐viologens in photocatalytic systems. [ABSTRACT FROM AUTHOR]

Redox‐active materials that exhibit both electrochromism and electrofluorochromism have great potential as multifunctional elements in optoelectronics. Here, in situ spectroelectrochemistry is presented on NU‐1000, a zirconium pyrenetetrabenzoate metal–organic framework. A thin film of NU‐1000 exhibits reversible color changes between light yellow and dark blue when subjected to an alternating electrochemical potential. In situ fluorescence excitation‐emission spectral mapping elucidates a dominant blue emission of highly fluorescent electrochromic NU‐1000 that is being quenched via an oxidation reaction. Density‐functional theory calculations reveal the forbidden optical transition between the singly occupied molecular orbital (SOMO) and the lowest unoccupied molecular orbital (LUMO) in the oxidized linker as the cause of the quenching. Double potential step chronoamperometry measures response times as fast as a dozen seconds and excellent switching stability over 500 cycles without noticeable attenuation of the color contrast. These findings provide valuable insight into the electrochromism and electrofluorochromism in metal–organic frameworks, offering exciting opportunities for developing advanced multifunctional porous materials with potential applications in optoelectronics and sensing. [ABSTRACT FROM AUTHOR]

Diarylethene (DAE) is one of the most widely used functional units for electrochromic or photochromic materials. To better understand the molecular modification effects on the electrochromic and photochromic properties of DAE, two modification strategies, substitution with functional groups or heteroatoms, were investigated theoretically by density functional theory calculations. It is found that red-shifted absorption spectra caused by a decreased highest occupied molecular orbital–lowest unoccupied molecular orbital energy gap and S0 → S1 transition energy during the ring-closing reaction become more significant by adding different functional substituents. In addition, for two isomers, the energy gap and S0 → S1 transition energy decreased by heteroatom substitution of S atoms with O or NH, while they increased by replacing two S atoms with CH2. For intramolecular isomerization, one-electron excitation is the most effective way to trigger the closed-ring (O → C) reaction, while the open-ring (C → O) reaction occurs most readily in the presence of one-electron reduction. Moreover, it is confirmed that substitution with strong electron donating groups (–OCH3/–NH2) or with one O/two CH2 heteroatoms leads to a more favorable closed-ring (O → C) reaction. Functionalized with strong electron-withdrawing groups (–NO2 and –COOH) or one/two NH heteroatom substitutions, the open-ring (C → O) reaction is easier. Our results confirmed that the photochromic and electrochromic properties of DAE can be tuned effectively by molecular modifications, which provides theoretical guidance for the design of new DAE-based photochromic/electrochromic materials. [ABSTRACT FROM AUTHOR]

An open-source automated system for laser modified layer by layer assembly is described. This flexible system, the first designed to be used with this process, can be used to fabricate a range of laser patterned, layer by layer thin films. The Arduino microcontroller-based system features a stepper motor-controlled turntable that holds solutions and water rinses for dipping. The substrate can be moved vertically to be dipped into each of the solutions throughout the process. A semiconductor laser is used to modify the thickness of the thin film during the chosen dipping cycles. Several aspects of the robotic system are easily controlled via software, including the average laser power, irradiation time, horizontal laser position, and vertical substrate position. The system is fully automated and, once started, does not require any user interaction. To demonstrate the capability of the automated system for patterning, electrochromic thin film devices using 50-bilayer laser patterned films using the polymers poly(allylamine hydrochloride) and sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate] are presented. One device is patterned with the shape of a large "C," created by irradiating the sample (55 mW average power, 405 nm) while the substrate was moved vertically up and down or the laser was moved horizontally. The laser irradiates the sample during only the dipping in the polycation polymer solution. A second electrochromic thin film device is based on a sample with five parallel laser patterned lines, where each line is fabricated with different average laser powers and, hence, different thicknesses. The thicknesses of the lines vary by about 30 nm. [ABSTRACT FROM AUTHOR]

In the pursuit of sustainable technology, the synthesis of a novel biopolymer, C‐pBPV, through the polymerization of carboxymethyl cellulose sodium salt (CMC‐Na) and viologen (BPV), with ammonium persulfate as an initiator is presented. This groundbreaking process not only promises an eco‐friendly approach but also opens avenues for advanced applications in electrochromic devices (ECDs), particularly in smart windows, displays, and beyond. Departing from conventional multi‐layered approaches, the study underscores the significance of a single‐layer material. C‐pBPV serves both as an electro‐chrome and an electrolyte, making it a compelling material for ECDs. It is used to create a gel‐based electrochromic device G1 with exceptional bistable properties. Following, a systematically controllable device, G2 is accomplished, to enhance color‐switching capabilities by adding vitamin C as an electron mediator. Both devices exhibited outstanding electrochromic properties, showcasing dual‐band absorption in the Vis‐NIR region, with color transitions from transparency to a striking purple state at low voltages. Embracing an all‐in‐one layer configuration, this study set the stage for next‐generation smart windows that not only regulate solar light for energy conservation but also pioneer a more compact, user‐friendly design, prioritizing visual comfort, sustainability, and a tailored user experience. [ABSTRACT FROM AUTHOR]

Reversible optical regulation has potential applications in optical anti-counterfeiting, storage, and catalysis. Compared to common power materials, the reverse opal structure has a larger specific surface area and an increased contact area for optical regulation, which is expected to achieve higher regulation rates. However, it is difficult to achieve reversible and repeatable regulation of the luminescent properties of photonic crystals, especially with the current research on the structural collapse of photonic crystals. In this work, WO3: Yb3+, Er3+ inverse photonic crystals were prepared by the template approach, and reversible multi-mode optical modification was investigated. Upon heat treatment in a reducing atmosphere or air, the color of the photonic crystals can reversibly change from light yellow to dark green, accompanied by changes in absorption and upconversion of luminescence intensity. The stability and fatigue resistance of this reversible optical modification ability were explored through cyclic experiments, providing potential practical applications for photocatalysis, optical information storage, and electrochromism. [ABSTRACT FROM AUTHOR]

In this work, tungsten oxide (WO3) films were deposited at room temperature and annealed for 2 h at 400°C. The electrochromic and electrochemical properties were studied for two different electrolytes. The films were deposited at different oxygen flow rates of 2, 4, and 6 standard cubic centimeters per minute (SCCM). X-ray diffraction analysis revealed structural characterization of amorphous and crystalline phases. UV-visible spectroscopy optical transmittance revealed 91% transmittance, and energy-dispersive x-ray spectroscopy (EDS) analysis revealed the absence of impurities and the presence of W and O. An electrochemical analyzer was used to characterize the deposited and annealed WO3 films immersed in the two different electrolyte solutions (H2SO4 and LiClO4 with oxygen flow rates ranging from 2 SCCM to 6 SCCM). It was found that the H2SO4 electrolyte of an annealed WO3 thin film at 2 SCCM demonstrated high coloring efficiency of 50.18 cm2/C, and the LiClO4 electrolyte of an annealed WO3 thin film at 4 SCCM demonstrated high coloring efficiency of 20.06 cm2/C. [ABSTRACT FROM AUTHOR]

The electrochromic (EC) mechanisms of inorganic materials are usually based on reversible cation insertion/extraction or metal deposition/dissolution, which are plagued by ion trapping and dendrite growth, respectively. In this paper, a novel conversion-type electrochromic mechanism is proposed, by making good use of the CuI/Cu redox couple. This CuI-based electrochromic system shows a neutral color switching from transparent and dim grey. By simply increasing the bleaching voltage, I 3 − / I − redox couple can be further activated. The generated I 3 − will readily react with Cu, effectively improving the conversion reversibility and thereby rejuvenating the degraded electrochromic performance. Thanks to the well-designed electrode and the self-healing ability, this conversion electrochromic system achieves rapid response times (tcoloring: 23 s, tbleaching: 6 s), decant optical modulation amplitude (26.4%), high coloration efficiency (86.15 cm2·C−1), admirable cyclic durability (without performance degradation after 480 cycles) and excellent optical memory ability (transmittance variation < 1% after 10 h open-circuit storage). The establishment of this conversion-type electrochromism may inspire the exploration of novel electrochromic materials and devices. [ABSTRACT FROM AUTHOR]

Electrically triggered color‐changing materials, termed as electrochromic materials, offer precise and programmable color transistions through the manipulation of electric field frequency and amplitude. They are used as displays, sensors, military camouflage, wearable devices, and anticounterfeiting materials. Their future advancements depend on clear understanding of the color change mechanisms and pros/cons between different electrochromic materials. To this end, we starts by categorizing electrochromism into two classes according to color production mechanism: chemical color‐based and physical color‐based. Within the former, color emerges from chemical molecules selectively absorbing specific wavelengths of light and color changes stem from electrochemical redox reactions. The latter, meanwhile, hinges upon electrically induced alterations in the geometries, dimensions, or arrangements of nano/micro structures, such as photonic crystals and plasmonic nanostructures. The principles of color changes in both categories are detailed, and compare their differences in terms of response time, operating voltage, degree of color change, and stability. At the end, their applications will be discussed spanning from smart windows to color display, dynamic camouflage, energy storage, and thermal management. This critical review is aimed to provide multidisciplinary insights that will benefit both novices and seasoned experts engaged in fundamental exploration or practical investigations of electrochromic materials. [ABSTRACT FROM AUTHOR]

Low-temperature, metastable electrochromism has been used as a tool to assign pigments in Photosystem I (PS I) from Thermosynechococcus vulcanus and both the white light and far-red light (FRL) forms of Chroococcidiopsis thermalis. We find that a minimum of seven pigments is required to satisfactorily model the electrochromism of PS I. Using our model, we provide a short list of candidates for the chlorophyll f pigment in FRL C. thermalis that absorbs at 756 nm, whose identity, to date, has proven to be controversial. Specifically, we propose the linker pigments A40 and B39 and two antenna pigments A26 and B24 as defined by crystal structure 1JB0. The pros and cons of these assignments are discussed, and we propose further experiments to better understand the functioning of FRL C. thermalis. [ABSTRACT FROM AUTHOR]

Distyrylbenzenes (DSBs) are well‐known for their strong multicolour fluorescence. Fluorescence tuning of DSB via further functionalization/arylation, on the other hand, is uncommon. This paper reports a Pd‐catalysed direct arylation approach for introducing different aryl groups onto fluorobenzene‐containing DSB moiety (7) in high yields (67–72 %). The versatile methodology allows the substitution of neutral [tolyl (1)], electron‐deficient [p‐formyl benzene (2), p‐acetyl benzene (3), p‐nitrobenzene (4)] and electron‐rich [carbazole (5), triphenylamine (6)] aryl groups. The electron‐deficient aryls render mono‐substitution, while the electron‐rich counterparts promote di‐substitution. The compounds (1–6) show blue, green, and yellow fluorescence in both the solution and solid states; the fluorescence quantum yields reach >98 % and the peak maxima span from 425 to 560 nm. The mono‐carbazole DSB (5) exhibit white light emission (WLM) in polar solvents (acetone, DMF, CH3CN, DMSO and NMP) with very high fluorescence quantum yields (φf) of 60–80 %. For WLM, such high efficiency (φf) is somewhat uncommon. Moreover, visible‐to‐NIR reversible electrochromism is demonstrated by the TPA‐integrated DSB (6). The colour of 6 changes from pristine light yellow to orange, and the absorption maxima shifts from 372 to 1500 nm when a positive potential of 1.0 V vs Ag/Ag+ is applied. Moreover, the system shows high colouration efficiency in the NIR region with fast switching speeds for colouration and decolouration as fast as 0.98 s and 1.05 s. [ABSTRACT FROM AUTHOR]

Electrochromic (EC) windows based on reversible metal electro-deposition/dissolution (RME) are exciting alternatives to static lighting control using blinds and shades. However, the difficulty of reversibly and uniformly electrodepositing large-area metal layers seriously hinders the development of RME-type EC windows. In this paper, we develop a novel EC system based on reversible oxide electro-deposition/dissolution (ROE) of MnO2, achieving a profound and bistable color change between rust brown and completely transparent. This ROE-MnO2 system exhibits a significantly high optical modulation amplitude (ΔT) without any deterioration within 1000 switching cycles (ΔT550nm actually increases from 44.8 % up to 46.9 % after the cycling test), which is almost double compared to the traditional cation-insertion/extraction triggered MnO2 (RCI-MnO2) EC system. This work may inspire the exploration of novel ROE-type EC systems. [ABSTRACT FROM AUTHOR]

The influence of the coating method (spray-coating or drop-casting onto horizontal substrate) on the electrochromic characteristics of the layers of water-soluble polyaniline–polyacid complex was investigated. It was shown that, in the case of adding single-wall nanotubes, the polyaniline–polyacid layers prepared by the scalable spray-coating technology demonstrate high coloration speed and electrochromic efficiency. [ABSTRACT FROM AUTHOR]

Simplified two-electrode electrochemical deposition technique with glass/tin-doped indium oxide (glass/ITO) has been used to grow Mg-doped CdS thin films. As precursors, CdCl2, MgCl2 and Na2S2O3 were utilized. To study the physico-chemical properties of the obtained Mg-doped CdS thin-film instruments such as grazing incidence X-ray diffraction and Raman spectroscopy for structural analysis, UV–Vis spectrophotometry for optical properties and scanning probe microscopy for morphological properties have been used. It is observed from grazing incidence X-ray diffraction (GIXRD) data that the films are polycrystalline with only hexagonal phase. Because more metallic ions are deposited on the substrate, the material becomes more crystalline and increases the intensity of distinctive peaks observed. From the obtained optical characterization, it is observed that deposition time significantly influences the bandgap of the film. As deposition time raised from 10 to 25 min the bandgap decreases from 2.44 to 2.39 which makes the film to become more transparent and absorbs less light at shorter deposition times. According to scanning electron microscope (SEM) images, the surface morphology is uniform with tightly packed grains, and as deposition time goes on the grain shapes become less apparent. [ABSTRACT FROM AUTHOR]

The metallo-supramolecular polymer (MSP) is considered one of the most promising electrodes for electrochromic devices due to its intrinsically stable redox properties. Nevertheless, despite extensive work focusing on improving the electrochromic and electrochemical properties of MSPs, little experimental evidence exists from in-depth investigations on the anion-induced electrochromism of MSPs. Herein, Ru-based metallo-supramolecular polymer (polyRu) films with excellent electrochromic performance were fabricated through a novel electrochemical deposition method, and the electrochromic mechanism was further understood. The polyRu films possess fast reaction kinetics with a short switching time of 4.0 s (colored) and 2.8 s (bleached) and highly reversible redox properties due to the resulting impacts on the capacitive behaviors (containing surface, near-surface and intercalation pseudo-capacitance) of the perchlorate ions in the electrochromic process. Moreover, the electrochromic degradation of the polyRu films is considered to stem from the numerous nanopores in the film induced by ClO4− transport and the exchange of counter anions from Cl− to ClO4−. In addition, a physical model, revealing the transport of conduction ions and the evolution of the structure and properties of the polyRu film during the electrochromic process, is presented. It is observed that the charge balance of Ru3+ and Ru2+, achieved through the adsorption/desorption of ClO4− on the film, provides electrochromic and electrochemical reversibility to the polyRu film under positive/negative bias. Correspondingly, a transformation from polyRu·(Cl−)2n to polyRu·(ClO4−)x(Cl−)2n−x in the polyRu film is induced by a counter anion exchange from Cl− to ClO4−. Revealing the detailed perchlorate ion transfer kinetics and electrochromic mechanism in this film can offer new insights into the application of metallo-supramolecular polymers in electrochromic devices. [ABSTRACT FROM AUTHOR]

Viologens, 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. [ABSTRACT FROM AUTHOR]

The memory effect property, described as a reversible color persistence while the potential is withdrawn, is of particular importance to reaching zero-energy consumption electrochromic devices. Nevertheless, often observed in organic materials, it is poorly studied in oxides. In this study, electrochromic tungsten oxide thin films are elaborated at different working pressures by radiofrequency magnetron sputtering. The influence of the deposition pressure on the electrochemical properties of WO3 films as well as on their memory effect is investigated. Three kinds of WO3 films can be distinguished: with irreversible blue coloration, with reversible coloration presenting a high memory effect, and with reversible coloration with a low memory effect. The origin of these discrepancies is studied through the composition, the local atomic environment, and the morphology of the WO3 thin films. An increase of transmittance at 550 nm as low as 15.8% in 48 h in air and 5.2% in 24 h in the electrolyte is recorded. This study highlights a better understanding of the memory effect property of electrochromic oxides for low-consumption energy electrochromic devices, pointing out morphology as a key parameter. [ABSTRACT FROM AUTHOR]

2, 6-monosubstituted aromatic phenolic resin (IPD-BPA-TPD) was prepared by microwave-assisted method using bisphenol A (BPA), terephthalaldehyde (TPD) and isophthalaldehyde (IPD) as co-condensation monomers based on an open system and solution polycondensation method. A reversible thermochromic nickel-based butadiene rubber film was prepared using resin as a chromogenic agent. The resin was tested by a gel permeation chromatograph, a nuclear magnetic resonance hydrogen spectrometer, a nuclear magnetic resonance carbon spectrometer, a thermogravimetric analyzer and a thermal analyzer. The composite film was tested by a thermogravimetric analyzer, a thermal analyzer, a spectrophotometer and a polarizing microscope. The thermochromic properties, thermal stability, thermal cycle stability and microstructure of the film were studied. The results show that the Mn of IPD-BPA-TPD is 1.133x10³ g/mol, the PDI is 1.005. The total color difference ΔE of the composite film reaches about 90 in the low temperature section (12~38 °C) of the constant-rate cooling phase transition, and the absorption/scattering color depth difference Δ (K/S) reach about 15 and 40 in the visible regions of 480~600 nm and 600~660 nm, and film has good thermal stability and thermal cycle stability. [ABSTRACT FROM AUTHOR]

Background: Gel dosimeters are a potential tool for measuring the complex dose distributions that characterize modern radiotherapy. A prototype tabletop solid‐tank fan‐beam optical CT scanner for readout of gel dosimeters was recently developed. This scanner does not have a straight raypath from source to detector, thus images cannot be reconstructed using filtered backprojection (FBP) and iterative techniques are required. Iterative image reconstruction requires a system matrix that describes the geometry of the imaging system. Stored system matrices can become immensely large, making them impractical for storage on a typical desktop computer. Purpose: Here we develop a method to reduce the storage size of optical CT system matrices through use of polar coordinate discretization while accounting for the refraction in optical CT systems. Methods: A ray tracing simulator was developed to track the path of light rays as they traverse the different mediums of the optical CT scanner. Cartesian coordinate discretized system matrices (CCDSMs) and polar coordinate discretized system matrices (PCDSMs) were generated by discretizing the reconstruction area of the optical CT scanner into a Cartesian pixel grid and a polar coordinate pixel grid, respectively. The length of each ray through each pixel was calculated and used to populate the system matrices. To ensure equal weighting during iterative reconstruction, the radial rings of PCDSMs were asymmetrically spaced such that the area of each polar pixel was constant. Two clinical phantoms and several synthetic phantoms were produced and used to evaluate the reconstruction techniques under known conditions. Reconstructed images were analyzed in terms of spatial resolution, signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), signal nonuniformity (SNU), and Gamma map pass percentage. Results: A storage size reduction of 99.72% was found when comparing a PCDSM to a CCDSM with the same total number of pixels. Images reconstructed with a PCDSM were found to have superior SNR, CNR, SNU, and Gamma (1 mm, 1%) pass percentage compared to those reconstructed with a CCDSM. Increasing spatial resolution in the radial direction with increasing radial distance was found in both PCDSM and CCDSM reconstructions due to the outer regions refracting light more severely. Images reconstructed with a PCDSM showed a decrease in spatial resolution in the azimuthal directions as radial distance increases, due to the widening of the polar pixels. However, this can be mitigated with only a slight increase in storage size by increasing the number of projections. A loss of spatial resolution in the radial direction within 5 mm radially from center was found when reconstructing with a PCDSM, due to the large innermost pixels. However, this was remedied by increasing the number of radial rings within the PCDSM, yielding radial spatial resolution on par with images reconstructed with a CCDSM and a storage size reduction of 99.26%. Conclusions: Discretizing the image pixel elements in polar coordinates achieved a system matrix storage size reduction of 99.26% with only minimal reduction in the image quality. [ABSTRACT FROM AUTHOR]

In this paper, Y4GeO8:Bi3+,Eu3+ phosphor with dual emission centers was elaborated via conventional solid‐state reaction technology. Thorough research on the structure, morphology, and luminous properties of Y4GeO8:Bi3+,Eu3+ phosphor, the potential applications in optical thermometry were investigated by means of fluorescence intensity ratio and thermochromic techniques. Under 290 and 347 nm excitation, Y4GeO8:Bi3+,Eu3+ phosphor presents broadband emission from 3P1 → 1S0 transition of Bi3+ ions and characteristic emission peaks from 4f–4f transition of Eu3+ ions. Outstanding temperature‐sensing capabilities are acquired from Y4GeO8:Bi3+,Eu3+ phosphor. The maximum relative sensitivity (Sr) can attain 1.51% K−1 (λex = 290 nm). With temperature raising (303–513 K), the emitted color of Y4GeO8:Bi3+,Eu3+ phosphor (λex = 290 nm) shifts from faint yellow to red with a high chromaticity shift (0.180), which can be distinguished by the unaided eye clearly. Our results indicate that Y4GeO8:Bi3+,Eu3+ phosphor has potential applications in optical temperature measurement and high‐temperature safety marker. [ABSTRACT FROM AUTHOR]

The AISI 304 (X5CrNi19‐10) stainless steel is widely used for the production of various metal parts in power plants. A procedure for testing the influence of the dust from a power plant on resistance to general and pitting corrosion of the AISI 304 stainless steel is developed and performed. The quantitative (XRD method) and qualitative (Fourier–transform infrared spectroscopy [FTIR] method) composition of the dust present in the power plant is determined. Applying the Mott–Schottky method, the properties of the passive layer are analyzed, while a degree of chromium depletion of the grain boundary is determined by the electrochemical potentiokinetic reactivation method with double loop method. Values of polarization resistance (linear polarization resistance and electrochemical impedance spectroscopy methods) and the corrosion current density (polarization measurements) indicate that the stainless steel has a higher resistance to general corrosion in the dust solutions than in the etalon solution. Also, based on the measured value of the pitting potential (Epit) and the difference between the values of the pitting potential and the corrosion potential (Epit – Ecorr), it can be seen that stainless steel has a higher resistance to localized types of corrosion, such as pitting corrosion, in dust solutions than in the etalon solution. [ABSTRACT FROM AUTHOR]

In this study, we enhance the angular-selective light absorption capabilities of guest–host liquid crystal (GHLC) cells by introducing a novel design featuring a uniform lying helix (ULH) structure. Previously GHLC cells, predominantly vertically aligned cells absorbed obliquely incident light but compromised x-direction visibility. In stark contrast, our ULH-based design allows incident light to seamlessly traverse transmittance in both z- and x-directions while efficiently obstructing oblique incident light in the y-direction. Our innovative ULH-based GHLC cell achieves an impressive optical performance. Specifically, it attains a substantial transmittance rate of 56.7% in the z-direction. Furthermore, in oblique views encompassing both the x- and y-directions, it maintains competitive transmittance rates of 44.2% and 29.5%, respectively. This strategic design not only ensures clear and unobstructed views for building occupants in the z- and x-directions but also contributes significantly to energy conservation by preventing oblique incident light from penetrating, thus reducing cooling requirements. Our ULH-based GHLC cell represents a breakthrough in smart window technology, offering an elegant solution to the challenge of balancing energy efficiency and occupant comfort in architectural settings. This advancement holds promising implications for sustainable building designs by enhancing indoor environmental quality while mitigating energy consumption for cooling, ultimately redefining the potential of smart windows in contemporary architecture. [ABSTRACT FROM AUTHOR]

This study presents a structuration approach to reach a high luminous transmittance (T l u m ) and solar modulation efficiency (Δ T s o l ) of thermochromic vanadium dioxide ( VO 2 ) thin films. Before starting optical simulations, we confirm that the optical properties of monoclinic VO 2 continuous films deposited by reactive magnetron sputtering show a good correspondence with numerical results. Then, calculations on ordered VO 2 nanostripes demonstrate an enhanced transmittance due to the presence of vertical openings, leading to a variety of photonic effects. A series of optimizations by varying the column width, period, and film thickness establishes that 20 nm wide and 10 nm separated nanostripes have a Δ T s o l of 14.2% and a T l u m of 47.6% for a film thickness of 250 nm. In comparison to a dense film without nanostructuring, the film transparency (related to T l u m ) is significantly enhanced, while Δ T s o l remains unchanged. Furthermore, this also translates into a favorable, less opaque color, so the geometry could be useful for various thermochromic applications, such as smart windows. [ABSTRACT FROM AUTHOR]

Many fossil insects show monochromatic colour patterns that may provide valuable insights into ancient insect behaviour and ecology. Whether these patterns reflect original pigmentary coloration is, however, unknown, and their formation mechanism has not been investigated. Here, we performed thermal maturation experiments on extant beetles with melanin-based colour patterns. Scanning electron microscopy reveals that melanin-rich cuticle is more resistant to degradation than melanin-poor cuticle: with progressive maturation, melanin-poor cuticle regions experience preferential thinning and loss, yet melanin-rich cuticle remains. Comparative analysis of fossil insects with monotonal colour patterns confirms that the variations in tone correspond to variations in preserved cuticle thickness. These preserved colour patterns can thus be plausibly explained as melanin-based patterning. Recognition of melanin-based colour patterns in fossil insects opens new avenues for interpreting the evolution of insect coloration and behaviour through deep time. [ABSTRACT FROM AUTHOR]

By using triphenylamine (TPA) with a propeller structure connected to the planar fluorene unit as monomer, three novel polyimide (PI)s were prepared through chemical imidization of N,N′‐(9,9‐bis(4‐(diphenylamino) phenyl)‐9H‐fluorene‐2,7‐diyl)‐bis(N‐(4‐methoxyphenyl) benzene‐1,4‐diamine) (TPAF‐NH2) with three kinds of dianhydrides. The three dimensional configurations are designed to decrease molecular stacking rising from strong imide bond, and for faster ion transport in cavity of PIs. All the three PIs have good performance of electrochromic(EC) and sensor. With the voltage increasing from 0 to 1.2 V, the color of P2 film changes from original yellow to red to blue with the response time of only 2.3 s (colored time [tc]) and 2.8 s (bleached time [tb]). The coloring efficiency (CE) of P2 reaches 310 cm2 C−1, with optical contrast (ΔT) of 54%. Especially, the electroactivity of P3 does not decrease significantly after 6000 s cycle. Additionally, there are dual‐band in near‐infrared (NIR) area after the PI being oxidized. P1 with photoluminescence (PL) quantum efficiency (φPL) of 48% can detect trinitrophenol (TNP) effectively. The novel PIs have promising prospect in NIR EC and TNP detection devices. [ABSTRACT FROM AUTHOR]

α, β, γ, δ—Copper(II) tetraphenylporphyrinate (CuTPP) has been investigated as an active material in composites for optoelectronic devices, such as organic light-emitting diodes (OLEDs). This study focused on the spectroscopic, structural, and morphological analysis of CuTPP thin films obtained using layer-by-layer deposition. The infrared spectra of the films, deposited both on ceramic glass and indium tin oxide-coated glass, revealed that the substrate interacts with CuTPP, inducing the formation of aliphatic CH2 or CH3 and a general rearrangement of the bands related to the bending of phenyl groups. UV–vis spectroscopy indicated the presence of two bands at 350 and 472 nm in the films, instead of the intense band in the region between 380 and 500 nm corresponding to the Soret band. The structure of the complex was elucidated by single-crystal X-ray diffraction. X-ray powder diffraction analysis showed that films exhibited two peaks associated with the 101 and 103 planes, which noticeably increased after heating at 200 °C. Scanning electron microscopy images confirmed that the annealing favored the growth of two-dimensional square-shaped aggregates on the surface of the substrate. [ABSTRACT FROM AUTHOR]

Cupric-oxide-based thin films with various amounts of 0, 1, 2, 3, and 4 wt.% Ni doping were, in turn, deposited on ITO/glass substrates via a solution process. The 0.25 M concentrated solutions of copper (II) acetate monohydrate and nickel acetate tetrahydrate were used as starting materials mixed in ethanol solvent, in order to form the precursors. We obtained that the crystalline structure was not affected by the increase in Ni doping concentration as evidenced by X-ray diffraction patterns. The surface morphology observed by scanning electron microscope pointed out the presence of linked-structure nanoparticles. The influence of Ni doping on the optical bandgap width was evaluated by using ultravioletvisible spectrometry. We found that the optical bandgap should be direct, and it decreased from 2.69 to 2.38 eV for the range doped. Interestingly, we determined the relaxation time of the Ni-doped CuO/ITO/glass structure from measuring the electrochemical impedance spectroscopy, and it was 0.36 s for the undoped film, then gradually decreased to be 0.31, 0.11, 0.1, and 0.04 s with increasing the Ni doping concentration. This achievement result will serve as a foundation for the future photonic researches. [ABSTRACT FROM AUTHOR]

The solid-state electrolytes have attractive properties for electrochromic (EC) devices and battery industries. Li+ ion is the most applied and investigated carrier ion in this field together with less commonly ions Mg2+, Na+ H+ and Al3+. In this study, we have investigated Al3+ solid electrolytes for WO3 based EC devices as alternative to Li+ ions. We have fabricated a series of AlSiOx thin films by applying different target powers of 0–15 W by magnetron sputtering method. The resulting films were characterized by Grazing incidence X-ray diffraction, atomic force microscopy, scanning electron microscopy, energy disperse spectroscopy, ultraviolet–visible-infrared spectrophotometer, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy (EIS). All samples showed high transparency in the visible range (~ 90%) while the transparency decreased about 10% in the near infrared region. Analysis of EIS data by Kramers–Kronig and Voigt models showed that some of the films have good ionic conductivity. The ionic conductivities of films grown with 10 W, 13 W and 15 W Al target powers were 1.54 × 10–6, 5.68 × 10–7 and 2.72 × 10–8 S/cm, respectively. The results indicate that AlSiOx solid electrolytes are promising for EC applications. [ABSTRACT FROM AUTHOR]

When an external stimulus is used to generate nanoscale wrinkles on the ductile top surface of a multilayered substrate, the geometrical and optical features are known to be controlled by the material and structural properties of the laminated film. Herein, a thin tri‐layer film is fabricated that can generate various wrinkles on transparent and flexible films in the presence of external mechanical bending. In particular, the wavelength of the wrinkles is shown to be controllable on the tens of nanometers scale by modulating the material properties of each layer. This active modulation plays a critical role in determining the resulting structural color spectra. In other words, the wrinkles function as a diffraction grating so that the film displays bright structural colors under bending conditions. After the bending stress is released, the wrinkles disappear, and the film returns to its transparent state. Finally, the remarkable potential of the material and structural patterning technique is demonstrated for structural coloration applications such as multimodal displays and novel barcode‐based anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

The current investigation is focused on modify optical, structural, electrical and electrochemical behaviors of PVA matrix by new hybrid ZnWMoO7 nanoparticles (NPs). The PVA/ZnWMoO7 nanocomposite (NCs) films have been fabricated via intercalation technique, where its structural and morphological features were investigated by XRD, SEM and FTIR. TEM result indicates that the size of nanoparticles (NPs) lies in the range of 7–18 nm. Current (I)–voltage(V) results showed dc-conductivity increased with increasing dosage of ZnWMoO7 NPs and I–V behavior indicates to ohmic dominant at voltage < 7 V followed by higher increasing in conductivity. The cyclic voltammetry (CV) displayed the PVA NCs have electrochemical stability between − 0.2 V and 0.8 V at a scan rate of 10 mV/S and the specific capacitance improved to 3.98 F/g for PVA/8wt% ZnWMoO7 NCs which is higher by 2 times compared to host PVA. The optical study reveals an increased refractive index from 1.18 to 2.16 at a wavelength of 300 nm, while the band gap energy (Eg) is reduced from 5.34 to 3.13 eV after inclusion PVA by 8wt% ZnWMoO7 NPs. Such results indicate that the NC films based on PVA/ZnWMoO7 NCs may be suitable for potential uses in opto-electronic and super capacitor applications. [ABSTRACT FROM AUTHOR]

The results of pure tungsten oxide WO3, 0.5% Fe-doped WO3 and 4% Fe‐doped WO3 deposited on the crystalline sapphire substrates by reactive pulsed laser deposition technique are reported. The crystalline structure of the thin films was investigated by X-ray diffraction. The thin films presented γ monoclinic and orthorhombic phases depending on the substrate temperature. The (200) and (400) diffraction peaks of the film grown at 600 °C and 650 °C have vanished. This effect was attributed to the Fe presence in the deposited layer. When the temperature increases to 720 °C, the films doped with Fe (0.5% and 4% Fe-doped WO3) behaved like an undoped WO3. The X Photoelectron Spectroscopy confirmed the existence of the W, Fe, and O species in the deposited layer of 4% Fe-doped WO3. Four dominant peaks of Fe 2p, detected by XPS measurements, show the existence of Fe3+. Two components O 1 s peaks were observed. The big peak located at 530 eV was responsible for the oxygen lattice in the WO3 matrix, and the additional peak at 532 eV presents oxygen deficiencies, dangling bonds, and O2 chemisorbed at the surface. The optical bandgap of thin films for 4% Fe-doped WO3 was slowly reduced from 3 to 2.7 eV as the substrate temperature increased from 600 to 720 °C. These values were compared with the optical bandgap of WO3 undoped thin film. The optical bandgap of the WO3 thin film was 3.1 eV at 720 °C. The optical emission of the pulsed laser deposition plasma plume shows the presence of the FeI and WI spectral lines. The rough estimation of the Fe percentage concentration was found from the FeI spectral line intensity ratio detected in the plasma plume and targets. [ABSTRACT FROM AUTHOR]

The nonlinear absorption (NLA) properties of ITO thin films were performed by utilizing femtosecond (100 fs), a high-repetition rate (80 MHz), and near-infrared (NIR) (750–820 nm) laser pulses. A radio frequency (RF) magnetron sputtering system was used to prepare ITO thin films of two different thicknesses. A scanning electron microscope was used to determine the film thickness and a UV–Visible spectrophotometer was used to observe the linear optical properties of the thin films. The open aperture Z-scan technique's nonlinear absorption studies of ITO thin films exhibited a reverse saturable absorption. The NLA properties of the ITO films varied depending on ITO thickness, incident laser power, and excitation wavelength, attributed to the increasing localized defect states in the band gap. The results showed that increasing the excitation wavelength from 750 to 820 nm reduces the nonlinear absorption coefficient of the ITO thin films from 15.88 × 10−7 to 9.43 × 10−7 cm/W and from 6.72 × 10−7 to 5.15 × 10−7 cm/W at ITO thicknesses of 280 and 170 nm, respectively. In contrast to the film thickness, the nonlinear absorption coefficient was inversely proportional to the excitation laser wavelength. Additionally, the optical limiting of ITO thin films was investigated, and it was found that there is a clear correlation between optical limiting and thin film thickness. [ABSTRACT FROM AUTHOR]

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Purple scapolite is a precious gemstone. In this paper, we compared the crystal structure and spectral characteristics of purple scapolite before and after heat treatment with conventional gemological tests, EPMA, XRF, LA-ICP-MS, infrared spectroscopy, Raman spectroscopy, UV–vis spectrophotometer, EPR, and other tests. The XRD results showed that the structure of purple scapolite fits perfectly with that of marialite. Compositional analyses indicate that purple scapolite has an average Me value of 16.85 and belongs to the subspecies marialite, and thus its specific gravity and refractive index are low. The absorption peak at 1045 cm−1 in the infrared spectra has a direct relationship with the Me value, which is blue-shifted with increasing Me value. After heating at 400 °C for 2 h, the purple scapolite changed to colorless, and no phase transformation or significant structural changes occurred during this process. But this process is accompanied by the disappearance of the signal at g = 2.011 in the EPR spectra, which indicates the presence of oxygen hole centers, thus proving that the color of purple scapolite is caused by oxygen hole centers rather than Fe3+. The chlorine in the marialite structure occupies the structural center, which provides for the appearance of oxygen hole centers, and thus purple scapolite always has a high marialite content. This further leads to the refractive index and specific gravity always being lower. That is a new explanation for the relationship between scapolite coloration mechanism, specific gravity, and refractive index. [ABSTRACT FROM AUTHOR]

Functional materials revealing mechanochromism behaviors are in high demand for potential applications. Here, we report a 1 : 1 cocrystal of naphtho[2,1-b]benzofuran (BNF) and 1,2,4,5-tetracyanobenzene (TCNB) that displayed a reversible crystal transition (of α- and β-forms) with a resulting change in emission color. The slight differences in cell dimensions, slipping angles between stacking columns, and TCNB orientation enabled this cocrystal to be a sensitive mechanochromic luminescent material. The α-form cocrystal showed significant bathochromic shifts upon being subjected to grinding or isotropic compression, and returned to the original state upon subsequently being subjected to a heating or fuming treatment. Based on detailed spectroscopic and structural analyses, the observed changes in luminescence were mainly attributed to the crystal having undergone a transformation at low pressure and then having formed an amorphous state as a result of damage to its structure. [ABSTRACT FROM AUTHOR]

High-performance donor-acceptor (D-A) polymers, as an important class of electrochromic (EC) materials, have attracted extensive attention. In this paper, a series of novel poly (aryl amino ketone) (PAAK) and poly (aryl amino sulfone) (PAAS) type high-performance polymers (HPP) with electrochromism were prepared by a simple C-N coupling reaction and were coated on an indium tin oxide (ITO) substrate as EC films. All four polymers were prepared by a nucleophilic substitution reaction using commercially purchased amine monomers with difluoride sulfone/ketone using potassium carbonate as a catalyst. A series of tests were performed to compare and analyze the effects of the different electron-withdrawing abilities of sulfone and carbonyl groups, and the different conjugation lengths of these two TPA structures were connected to the EC properties of the polymer. The different phenyl or biphenyl of the two TPA structures mainly affected the oxidation potential of the polymer, while the sulfone group and the carbonyl group, with a different electron absorption ability, had a greater influence on the energy band and cyclic stability. The optical contrast of PAAS−BT at 850 nm was up to 58% and maintained 450 cycles, indicating that this series of materials had a broad application prospect waiting for further research. In addition to the performance, the raw materials used in this work could be directly and commercially purchased for a low price; the two aniline monomers were priced at about $0.43 /g and $0.15 /g, respectively. This method significantly reduces the cost and provides a new idea for subsequent large-scale production and practical applications. [ABSTRACT FROM AUTHOR]

A PMMA-based gel polymer electrolyte (GPE) modified by a plastic crystal succinonitrile (SN) was synthesized using a facile solvent-casting method. The effects of SN additives upon lithium-ion dissociation and ionic conductivity were investigated primarily using Fourier transform infrared spectroscopy and electrochemical impedance spectroscopy, accompanied by other structural characterization methods. The results show that SN is distributed uniformly in the PMMA matrix with a high content and produces vast dipoles that benefit the dissociation of lithium salt. Hence, the SN-modified GPE (SN-GPE) achieves an excellent ionic conductivity of 2.02 mS·cm−1 and good mechanical properties. The quasi-solid-state ECD fabricated using the SN-GPE exhibits stable cyclability and excellent electrochromic performance, in which the bleaching/coloration response time is 10 s/30 s. These results add significant insight into understanding the inter- and intra-molecular interaction in SN-GPEs and provide a type of practicable high-performance GPE material for solid electrochromic devices. [ABSTRACT FROM AUTHOR]