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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]

An integrated visual energy system consisting of conjugated polymer electrodes is promising for combining electrochromism with energy storage. In this work, we obtained copolymer bifunctional electrodes poly(3,6-dimethoxythieno[3,2-b]thiophene-co-2,3-dihydrothieno[3,4-b][1,4]dioxin-3-ylmethanol)(P(TT-OMe-co-EDTM)) by one-step electrochemical copolymerization, which exhibits favorable electrochromic and capacitive energy storage properties. Because of the synergistic effect of PTT-OMe and PEDTM, the prepared copolymers show better flexibility. Moreover, the morphology and electrochemical properties of the copolymers could be adjusted by depositing different molar ratios of 3,6-dimethoxythieno[3,2-b]thiophene (TT-OMe) and 2,3-dihydrothieno[3,4-b][1,4] dioxin-3-ylmethanol (EDTM). The P(TT-OMe-co-EDTM) electrodes realized a high specific capacitance (190 F/g at 5 mV/s) and recognizable color conversion. This work provides a novel and simple way to synergistically improve electrochromic and energy storage properties and develop thiophene-based conducting polymers for electrochromic energy storage devices. [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]

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]

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]

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]

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 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]

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]

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]

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]

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]

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]

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]

Vanadium dioxide (VO 2) is a key material for thermochromic smart windows that can respond to environmental temperature to regulate near-infrared transmittance automatically. To date, VO 2 -based smart windows have made great progress, but practical applications still remain restricted by two tough challenges, i.e., low solar regulation ability and unpopular color. In view of the above two challenges, in this paper, novel warm/cool-tone switchable VO 2 -based composite films were designed and prepared. The novel composite films demonstrate outstanding optical properties: Δ T sol = 18.92% and T lum,l = 48.70%. The high solar modulation efficiency is attributed to the modulation of the thermochromic microcapsules in visible light waveband and VO 2 in near-infrared region. Meanwhile changes in color of the composite films at different temperatures were also studied in order to develop high-performance warm/cool-tone switchable thermochromic smart windows. These promising results will benefit to promote the popularization and application of smart windows. [ABSTRACT FROM AUTHOR]

Hiding terrestrial objects from aerial monitoring has long been an important objective in national security and public safety. However, the diversity of terrestrial environments raises great challenges to traditional camouflages optimized for a single spectral band or single type of background environment, rendering them vulnerable in other bands or backgrounds. Herein, we experimentally demonstrate simultaneous visual and thermal camouflage that can adapt to two different environments based on a thermally emissive electrochromic layer. We first explore diverse possible theoretical solutions for dual-band dual-environmental camouflage by solving analytic constraints for camouflage and steady-state thermal conditions and select the most viable approach. Based on the theoretical analysis, we design active camouflage thin-film material systems that can approximate two different target visible and infrared signatures of backgrounds under proper bias voltage. Our potentially flexible camouflage surfaces can also conceal heat sources such as human body as well with tailored designs. These results provide new directions in multi-band stealth designs. [ABSTRACT FROM AUTHOR]

Prey animals typically try to avoid being detected and/or advertise to would-be predators that they should be avoided. Both anti-predator strategies primarily rely on colour to succeed, but the specific patterning used is also important. While the role of patterning in camouflage is relatively clear, the design features of aposematic patterns are less well understood. Here, we use a comparative approach to investigate how pattern use varies across a phylogeny of 268 species of cryptic and aposematic butterfly larvae, which also vary in social behaviour. We find that longitudinal stripes are used more frequently by cryptic larvae, and that patterns putatively linked to crypsis are more likely to be used by solitary larvae. By contrast, aposematic larvae are more likely to use horizontal bands and spots, but we find no differences in the use of individual pattern elements between solitary and gregarious aposematic species. However, solitary aposematic larvae are more likely to display multiple pattern elements, whereas those with no pattern are more likely to be gregarious. Our study advances our understanding of how pattern variation, coloration and social behaviour covary across lepidopteran larvae, and highlights new questions about how patterning affects larval detectability and predator responses to aposematic prey. [ABSTRACT FROM AUTHOR]

Flexible and stretchable electronic devices are indispensable parts of wearable devices. However, these electronics employ electrical transducing modes and lack the ability to visually respond to external stimuli, restricting their versatile application in the visualized human–machine interaction. Inspired by the color variation of chameleons' skin, we developed a series of novel mechanochromic photonic elastomers (PEs) with brilliant structural colors and a stable optical response. Typically, these PEs with a sandwich structure were prepared by embedding PS@SiO2 photonic crystals (PCs)within the polydimethylsiloxane (PDMS) elastomer. Benefiting from this structure, these PEs exhibit not only bright structural colors, but also superior structural integrity. Notably, they possess excellent mechanochromism through lattice spacing regulation, and their optical responses are stably maintained even when suffering from 100 stretching–releasing cycles, showing superior stability and reliability and excellent durability. Moreover, a variety of patterned PEs were successfully obtained through a facile mask method, which provides great inspiration to create intelligent patterns and displays. Based on these merits, such PEs can be utilized as visualized wearable devices for detecting various human joint movements in real time. This work offers a new strategy for realizing visualized interactions based on PEs, showing huge application prospects in photonic skins, soft robotics, and human–machine interactions. [ABSTRACT FROM AUTHOR]

The Zn anode-based electrochromic energy storage devices (EESDs) provide a promising strategy to overcome the contradiction of electrochromism and energy storage for efficient devices. In this regard, the device configuration can endow the electrochromic devices with superior electrochromic performance and excellent energy recovery efficiencies. [Display omitted] With the emerging demand of multifunctional optoelectronic devices, the integration of electrochromism and energy storage functionalities within a single platform has become a research frontier in the electrochromic community. However, the conventional electrochromic function is inherently contradictory to the energy storage function in electrochromic devices. In this review, we firstly introduced the working principles and device configurations of the rudimentary electrochromic energy storage devices (EESDs), where the origin of the contradiction between electrochromic and energy storage functionalities is comprehensively introduced. We then reviewed the current status and applications of EESDs, where we hope to clearly reveal the developing trends of the EESDs. Finally, we proposed our perspectives on the design strategy of zinc anode-based electrochromic devices for overcoming the contradiction between electrochromism and energy storage of EESDs. [ABSTRACT FROM AUTHOR]

In this article, we report the growth of Cu2ZnSnS4 (CZTS) films using a pulsed-laser deposition technique, to use as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). A pulsed Nd-YAG laser in third harmonic generation (wavelength: 266 nm; pulse width: 9 ns and pulse frequency: 5 Hz) was used to ablate CZTS target. The ablated CZTS material was deposited on fluorine-doped tin oxide-coated glass substrate kept at 200°C under the vacuum of 6×10–6 mbar followed by annealing at 500°C to obtain CZTS films. Detailed characterization of the CZTS films was performed using X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The ablation of the CZTS target by 1000 laser pulses (energy: 200 mJ) was found to result in the formation of a well-crystalline CZTS with characteristic weak and strong Raman modes at 287 and 337 cm–1. The CZTS films with different thicknesses were prepared by varying the number of laser pulses. Thickness-dependent electrocatalytic ability and electrochemical properties of the CZTS CEs were studied by cyclic voltammeter, electrochemical impedance spectroscopy and Tafel polarization. The thickness-dependent performance of DSSCs made with CZTS CEs was measured through J–V characterization. The DSSC based on CZTS CEs deposited with the thickness ~ 225 nm (ablated with 1000 laser pulses) showed maximum power conversion efficiency of 3.98%. The results indicated the potentiality of CZTS to replace Pt CE (5.53%) in DSSCs. [ABSTRACT FROM AUTHOR]

Hexagonal molybdenum oxide (h-MoO3) micro-rods were synthesized through a facile hydrothermal method. Thermogravimetric and differential thermal analysis (TGA-DTA) of the sample, over temperatures ranging from 30°C to 700°C, was carried out to analyze the phase transition characteristics and thermal stability. The effect of post-thermal treatment on the structural, morphological, and optical characteristics of as-prepared samples were investigated in detail. X-ray diffraction (XRD) patterns of the sample confirmed the formation of h-MoO3, and the presence of hexagonal-shaped micro-rods were observed through scanning electron microscopy (SEM). The crystalline phase was transformed to a thermodynamically stable orthorhombic structure (α-MoO3) on thermal treatment, with the micro-rods transformed to flake-like morphology. Elemental composition was confirmed through energy dispersive x-ray spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS). Band gap energy estimated from the absorption spectra lies in the range 2.70–2.94 eV. The material exhibited a superior irreversible thermochromic property, which has been observed as color bands, in the visible to NIR region of the absorption spectra. The phenomenon was well explained with the support of the XPS scan for the Mo-3d and O-1 s states. Furthermore, the photoluminescence (PL) spectra, at an excitation of 330 nm (3.76 eV), showed five emission peaks centered between 360 nm and 550 nm, with enhanced intensity on thermal treatment. The physico-chemical characteristics revealed that the material can be applicable in thermo-chromic smart windows and as host material in light-emitting diodes. [ABSTRACT FROM AUTHOR]

Electrochromic materials play a key role in smart windows, displays or anti‐glare rear‐view mirrors. Tungsten oxide is an intensely studied representative due to its extraordinary coloring performance. For commercial use, however, further optimization of the general cycle stability as well as the protection against external factors, such as moisture, is a still ongoing focus of research. In this study, the stabilization of the electrochromic switching performance of tungsten oxide is investigated using an ultrathin optimized Al2O3 protective coating, grown by atomic layer deposition. Amorphous tungsten oxide (a‐WOx) thin films are prepared by reactive radio‐frequency sputtering. The composition as well as electronic structure of the pure a‐WOx films is studied by X‐ray photoelectron spectroscopy. The electrochromic properties of the multilayer system are investigated in a nonaqueous electrolyte as well as in an electrolyte containing 10 vol% water. On the basis of these results, the stabilizing effect on the electrochromic switching characteristics of a‐WOx by the use of the additional thin Al2O3 protective layer is evident. It is shown that degradation and ageing of a‐WOx due to moisture can be prevented and coloration efficiencies of 50.4 cm2 C−1 can be achieved at 630 nm. [ABSTRACT FROM AUTHOR]

Highlights: A timely and updated comprehensive overview focusing on integration of electrochromic aqueous batteries is provided. The key prerequisites of integration, basic operating mechanism, and compatibility of the respective components are examined. The latest advances and emerging applications are discussed, as well as the future roadmap. Multifunctional electrochromic-induced rechargeable aqueous batteries (MERABs) integrate electrochromism and aqueous ion batteries into one platform, which is able to deliver the conversion and storage of photo-thermal-electrochemical sources. Aqueous ion batteries compensate for the drawbacks of slow kinetic reactions and unsatisfied storage capacities of electrochromic devices. On the other hand, electrochromic technology can enable dynamically regulation of solar light and heat radiation. However, MERABs still face several technical issues, including a trade-off between electrochromic and electrochemical performance, low conversion efficiency and poor service life. In this connection, novel device configuration and electrode materials, and an optimized compatibility need to be considered for multidisciplinary applications. In this review, the unique advantages, key challenges and advanced applications are elucidated in a timely and comprehensive manner. Firstly, the prerequisites for effective integration of the working mechanism and device configuration, as well as the choice of electrode materials are examined. Secondly, the latest advances in the applications of MERABs are discussed, including wearable, self-powered, integrated systems and multisystem conversion. Finally, perspectives on the current challenges and future development are outlined, highlighting the giant leap required from laboratory prototypes to large-scale production and eventual commercialization. [ABSTRACT FROM AUTHOR]

To improve the electrochromic (EC) properties of sol–gel-derived WO3 films, a series of organic small molecules, such as dopamine (DA), catechol, tyramine, phenol and 2-phenylethylamine, were added into peroxotungstic acid precursor sols as structure-directing additives, and five modified WO3 films were prepared by a simple and low-cost complexation-assisted sol–gel method. The effects of the above additives on the EC properties of the modified WO3 films have been studied in detail. Compared with the pure WO3 polycrystalline film, all the modified films combine the advantages of nanocrystalline and amorphous phases and show higher EC properties attributed to the unique nanocrystal-embedded amorphous structure. The results indicate that different additives with different numbers and types of functional groups (hydroxyl and amino groups) can change the microstructure, morphology, and thus electrochemical and EC properties of the films in various degrees. The additives, in order of their strong interactions with the sols, are DA, catechol, tyramine, phenol and 2-phenylethylamine, primarily depending on the number of hydroxyl groups. Of all the additives, DA with both catechol hydroxyl and amino groups shows the most positive effect; that is, the WO3 film modified with DA exhibits the best EC properties in terms of contrast, switching speed, stability, and coloration efficiency. [ABSTRACT FROM AUTHOR]

Tungsten disulfide (WS2) was prepared from W metal and WO3 by ion beam sputtering and sulfurization in a different number of layers, including monolayer, bilayer, six-layer, and nine-layer. To obtain better crystallinity, the nine-layer of WS2 was also prepared from W metal and sulfurized in a furnace at different temperatures (800, 850, 900, and 950 °C). X-ray diffraction revealed that WS2 has a 2-H crystal structure and the crystallinity improved with increasing sulfurization temperature, while the crystallinity of WS2 sulfurized from WO3 (WS2-WO3) is better than that sulfurized from W-metal (WS2-W). Raman spectra show that the full-width at half maximum (FWHM) of WS2-WO3 is narrower than that of WS2-W. We demonstrate that high-quality monocrystalline WS2 thin films can be prepared at wafer scale by sulfurization of WO3. The photoluminescence of the WS2 monolayer is strongly enhanced and centered at 1.98 eV. The transmittance of the WS2 monolayer exceeds 80%, and the measured band gap is 1.9 eV, as shown by ultraviolet-visible-infrared spectroscopy. [ABSTRACT FROM AUTHOR]

Vanadium dioxide (VO2) has promising applications in smart windows and active micro-optical devices due to its thermochromic properties. However, the successful fabrication and patterning of VO2 thin films with the correct stoichiometry and phase are challenging. In this study, we investigated lithographically patterned and non-patterned VO2 thin films fabricated by reactive ion beam deposition, using variable angle spectroscopic ellipsometry, Raman spectroscopy, and transmission and reflection measurements. The results show that the refractive index and extinction coefficient exhibit significant changes for near-infrared wavelengths when heated above 68 °C, confirming its thermochromic properties. The Raman spectroscopy results indicate the formation of the monoclinic phase VO2(M) after annealing, which was not changed by reactive ion etching. Lithographically structured VO2-layers were successfully realized demonstrating the potential of VO2 as a material for active micro-optical devices, such as guided mode resonance filters with switchable reflectance. The results suggest that VO2 has great potential as a promising material for actively switched optical elements and micro-optical devices. [ABSTRACT FROM AUTHOR]

Recent years have witnessed a rapid development in the field of structural coloration, colors generated from the interaction of nanostructures with light. Compared to conventional color generation based on pigments and dyes, structural color generation exhibits unique advantages in terms of spatial resolution, operational stability, environmental friendliness, and multiple functionality. Here, we discuss recent development in structural coloration based on layered thin films and optical metasurfaces. This review first presents fundamentals of color science and introduces a few popular color spaces used for color evaluation. Then, it elaborates on representative physical mechanisms for structural color generation, including Fabry–Pérot resonance, photonic crystal resonance, guided mode resonance, plasmon resonance, and Mie resonance. Optimization methods for efficient structure parameter searching, fabrication techniques for large-scale and low-cost manufacturing, as well as device designs for dynamic displaying are discussed subsequently. In the end, the review surveys diverse applications of structural colors in various areas such as printing, sensing, and advanced photovoltaics. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the effectiveness of in-office bleaching in esthetic dentistry on the roughness and color stability of the enamel surface, using different concentrations of hydrogen peroxide (HP). Fifty human incisors were randomly divided into 5 groups (n = 10). No bleaching was performed in the control group. For these groups, concentrations of 40% HP with fluoride (F), 35% HP with calcium (Ca), 25% HP with nano-hydroxyapatite (nHA) and 18% HP with nHA were used for bleaching in the test groups. Surface roughness was assessed at baseline after bleaching occurred. Color measurements were first obtained at baseline, then after the first and second sessions of bleaching, and, finally, after the staining protocol. Scanning electron microscopy and atomic force microscopy were performed. Statistical analysis was conducted with a one-way ANOVA, followed by a post hoc Tukey's test and a paired-samples t-test (p < 0.05). All the bleaching gels used exhibited a similar color change (p > 0.05). Bleaching gels containing 18% HP with nHA and that containing 35% HP with Ca caused less surface roughness of the enamel. Of these concentrations, 25% HP with nHA caused the most surface roughness and no significant difference was observed, compared with 40% HP with F. The highest coloration after bleaching was observed in 40% HP with F and 25% HP with nHA. The lowest coloration was obtained in 35% HP with Ca and 18% HP with nHA but no significant difference was observed between them and the control group. A concentration above 18% HP does not increase the bleaching effectiveness. The results show that 18% HP with nHA and 35% HP with Ca resulted in the least increase in enamel surface roughness when compared to high-concentrate HP; however, it also prevented recoloration after bleaching. [ABSTRACT FROM AUTHOR]

A new electrochemical impedimetric sensor for direct detection of urea was designed and fabricated using nanostructured screen-printed electrodes (SPEs) modified with CuO/Co3O4 @MWCNTs. A facile and simple hydrothermal method was achieved for the chemical synthesis of the CuO/Co3O4 nanocomposite followed by the integration of MWCNTs to be the final platform of the urea sensor. A full physical and chemical characterization for the prepared nanomaterials were performed including Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), contact angle, scanning electron microscope (SEM) and transmission electron microscopy (TEM). Additionally, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to study the electrochemical properties the modified electrodes with the nanomaterials at different composition ratios of the CuO/Co3O4 or MWCNTs. The impedimetric measurements were optimized to reach a picomolar sensitivity and high selectivity for urea detection. From the calibration curve, the linear concentration range of 10−12–10−2 M was obtained with the regression coefficient (R2) of 0.9961 and lower detection limit of 0.223 pM (S/N = 5). The proposed sensor has been used for urea analysis in real samples. Thus, the newly developed non-enzymatic sensor represents a considerable advancement in the field for urea detection, owing to the simplicity, portability, and low cost-sensor fabrication. [ABSTRACT FROM AUTHOR]

Smart materials are highly desirable over the recent decade due to the growing demand on complicated nature. Smart materials with stable stimuliresponsive properties are widely applied in sensors, smart windows, displays, and chemical valves, but they are relatively rare. Most of the current chromic materials are triggered by one or two external stimuli, and only a few multi-stimuli responsive instances still suffer by their restricting functional states, such as solution or polymer. To address these challenges, researchers are focusing their efforts on developing a new generation of multi-stimulus responsive chromic materials. In this article, our group has adopted a new strategy for the synthesis of the multi-stimuli responsive single polymeric material, which can be useful for different applications (such as thermochromism, photochromism, electrochromism, and solvatofluorochromism). Thiazolothiazole viologen (TTv)-containing poly(2-isopropyl-2-oxazoline) (PiPO) was synthesized using a one-pot reaction where the living cationic polymer chains were reacted with thiazolothiazole viologen to produce multi-stimuli responsive PiPO-TTv. PiPO-TTv-based device demonstrated multi-responsive properties due to the thermoresponsive properties of PiPO segments and photo-, electro-responsive properties of TTv monomer, respectively. PiPO-TTv material, additionally exhibits fluorescence characteristics that makes it appealing for environmental and molecular biological sensor applications. [ABSTRACT FROM AUTHOR]

Vanadium dioxide (VO2) with an insulator-to-metal (IMT) transition (∼68 °C) is considered a very attractive thermochromic material for smart window applications. Indeed, tailoring and understanding the thermochromic and surface properties at lower temperatures can enable room-temperature applications. The effect of W doping on the thermochromic, surface, and nanostructure properties of VO2 thin film was investigated in the present proof. W-doped VO2 thin films with different W contents were deposited by pulsed laser deposition (PLD) using V/W (+O2) and V2O5/W multilayers. Rapid thermal annealing at 400–450 °C under oxygen flow was performed to crystallize the as-deposited films. The thermochromic, surface chemistry, structural, and morphological properties of the thin films obtained were investigated. The results showed that the V5+ was more surface sensitive and W distribution was homogeneous in all samples. Moreover, the V2O5 acted as a W diffusion barrier during the annealing stage, whereas the V+O2 environment favored W surface diffusion. The phase transition temperature gradually decreased with increasing W content with a high efficiency of −26 °C per at. % W. For the highest doping concentration of 1.7 at. %, VO2 showed room-temperature transition (26 °C) with high luminous transmittance (62%), indicating great potential for optical applications. [ABSTRACT FROM AUTHOR]

Functional polymers featuring good processability in non-halogenated, benzene-free green solvents are highly desired due to health and environmental concerns. Herein, a series of novel D-A type conjugated polymers, PBDT-IIDs, are designed and successfully prepared by "green" functionalization of the polymers with highly hydrophilic, highly polar, highly flexible, and biocompatible oligoethylene glycol (OEG) side chains in order to improve the processability. These series polymers are named PBDT-IID2, PBDT-IID3, and PBDT-IID4, respectively, according to the number of oxygen atoms in the side chain. After confirmation by structural characterization, the basic properties of PBDT-IIDs are also investigated. With the increase in the OEG side chain length, the polymer PBDT-IID4 not only has good solubility in the halogen solvent chlorobenzene, but also exhibits excellent solubility in the green halogen-free solvent methyltetrahydrofuran (Me-THF). As a result, the green solvent Me-THF can also be applied to prepare PBDT-IIDs' electrochromic active layers, except for chlorobenzene and toluene. The electrochromism of PBDT IIDs under both positive and negative voltages has a practical application potential. The several controllable switches between dark green and khaki (0–0.6 V) are expected to show great potential in the field of military camouflage. Furthermore, according to the principle of red, green, and blue (RGB) mixing, light blue-green in the reduced state (−1.6 V) can be used in the preparation of complementary ECDs to provide one of the three primary colors (green). [ABSTRACT FROM AUTHOR]

Behavioral ecologists have long studied the role of coloration as a defense against natural enemies. Recent reviews of defensive coloration have emphasized that these visual signals are rarely selected by single predatory receivers. Complex interactions between signaler, receiver, and environmental pressures produce a striking array of color strategies—many of which must serve multiple, sometimes conflicting, functions. In this review, we describe six common conflicts in selection pressures that produce multifunctional color patterns, and three key strategies of multifunctionality. Six general scenarios that produce conflicting selection pressures on defensive coloration are: (1) multiple antagonists, (2) conspecific communication, (3) hunting while being hunted, (4) variation in transmission environment, (5) ontogenetic changes, and (6) abiotic/physiological factors. Organisms resolve these apparent conflicts via (1) intermediate, (2) simultaneous, and/or (3) plastic color strategies. These strategies apply across the full spectrum of color defenses, from aposematism to crypsis, and reflect how complexity in sets of selection pressures can produce and maintain the diversity of animal color patterns we see in nature. Finally, we discuss how best to approach studies of multifunctionality in animal color, with specific examples of unresolved questions in the field. [ABSTRACT FROM AUTHOR]

Three homologous electrochromic conjugated polymers, each containing an asymmetric building block but decorated with distinct alkyl chains, were designed and synthesized using electrochemical polymerization in this study. The corresponding monomers, namely T610FBTT810, DT6FBT, and DT48FBT, comprise the same backbone structure, i.e., an asymmetric 5-fluorobenzo[c][1,2,5]thiadiazole unit substituted by two thiophene terminals, but were decorated with different types of alkyl chain (hexyl, 2-butyloctyl, 2-hexyldecyl, or 2-octyldecyl). The effects of the side-chain structure and asymmetric repeating unit on the optical absorption, electrochemistry, morphology, and electrochromic properties were investigated comparatively. It was found that the electrochromism conjugated polymer, originating from DT6FBT with the shortest and linear alkyl chain, exhibits the best electrochromic performance with a 25% optical contrast ratio and a 0.3 s response time. The flexible electrochromic device of PDT6FBT achieved reversible colors of navy and cyan between the neutral and oxidized states, consistent with the non-device phenomenon. These results demonstrate that subtle modification of the side chain is able to change the electrochromic properties of conjugated polymers. [ABSTRACT FROM AUTHOR]

Thermofluorochromic materials exhibit tunable fluorescence emission on heating or cooling. They are highly desirable for applications ranging from temperature sensing to high-security anti-counterfeiting. Luminescent matrices based on liquid crystals are very promising, particularly those based on liquid crystals with intrinsic fluorescence. However, only a few examples have been reported, suggesting ample margins for development in the field, due to the wide range of fluorophores and supramolecular organizations to be explored. Moreover, thermofluorochromic liquid crystals can be tailored with further functionalities to afford multi-stimuli responsive materials. For the first time, herein we report the thermofluorochromism of thienoviologen liquid crystals, already known to show bulk electrochromism and electrofluorochromism. In particular, we studied their photophysics in the 25 °C–220 °C range and as a function of the length of the N-linear alkyl chains, m (9 ≤ m ≤ 12 C atoms), and the type of anion, X (X = OTs-, OTf-, BF4-, NTf2-). Interestingly, by changing the parameters m, X and T, their fluorescence can be finely tuned in the whole visible spectral range up to the NIR, by switching among different mesophases. Importantly, by fixing the structural parameters m and X, an interesting thermofluorochromism can be achieved for each thienoviologen in a homologous series, leading to a switch of the emitted light from red to green and from white to blue as a consequence of the temperature-induced variation in the supramolecular interactions in the self-assembled phases. [ABSTRACT FROM AUTHOR]

Electrochromic devices are the preferred devices for smart windows because they work independently of uncontrollable environmental factors and rely more on the user's personal feelings to adjust actively. However, in practical applications, the ambient temperature still has an impact on device performance, such as durability, reversibility and switching performance, etc. These technical issues have significantly slowed down the commercialization of electrochromic devices (ECDs). It is necessary to investigate the main reasons for the influence of temperature on the device and make reasonable optimization to enhance the effectiveness of the device and extend its lifetime. In recent years, with the joint efforts of various outstanding research teams, the performance of electrochromic devices has been rapidly improved, with a longer lifetime, richer colors, and better color contrast. This review highlights the important research on temperature–dependent electrochromic properties in recent years. Also, the reported structures, mechanisms, characteristics, and methods for improving electrochromic properties are discussed in detail. In addition, the challenges and corresponding strategies in this field are presented in this paper. This paper will inspire more researchers to enrich the temperature–dependent properties of ECDs and their related fields with innovative means and methods to overcome the technical obstacles faced. [ABSTRACT FROM AUTHOR]

We report the synthesis and investigation of Au–Ru composite with highly developed specific surface area exhibiting excellent electrocatalytic performance suitable for detection of such hydrophobic metabolites as epinephrine in the physiological environment. This electrode material was fabricated using two-stage laser-assisted metal deposition technique. The morphological and structural studies of Au–Ru were performed using methods of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction spectroscopy (XRD). The voltammetric methods, including cyclic voltammetry (CV), differential pulse voltammetry (DPV) and direct amperometry, were used to analyze the composite's electrochemical properties. The Au–Ru sensor exhibited two linear ranges of the non-enzymatic epinephrine detection: 0.01–10 μM and 10–1000 μM. The calculated sensitivities within these two ranges were 32.8 and 3.3 μA μM − 1 cm − 2 , whereas the corresponding limits of detection were 9 and 20 nM, respectively. The Au–Ru sensor also revealed good stability and reproducibility, as well as high selectivity towards epinephrine detection in the presence of a number of the interfering species. [ABSTRACT FROM AUTHOR]

Prussian blue (Fe4[Fe(CN)6]3, PB) has become a widely studied anodic electrochromic material due to its advantages such as large optical modulation range, fast response speed and low voltage demand. Tungsten oxide (WO3) as a cathode electrochromic materials, have various advantages, while their low color rendering efficiency and poor cycling stability limit their applications. To this end, the following solution was proposed for the first time in this study: the hydrothermal method was adopted to prepare tungsten oxide nanorods and then coat Prussian blue on the rod-shaped tungsten oxide to form an inorganic–organic core–shell structure (WO3/PB) to improve electrochromic performance. Through comparative experiments, the effects of WO3/PB core–shell structure for the electrochromic properties of films and its mechanism were explored. The Li+ diffusion coefficient of WO3/PB core–shell structure films is 35% and 720% higher than that of single WO3 and PB, respectively. At the same time, compared with the single PB and WO3 films, the electrochromic response speed of the WO3/PB film is fast, and the light transmittance after coloring is low, with good optical properties. Relevant experimental data displayed that WO3 is wrapped by PB to form a core–shell structure, which makes the film have high electrochromic properties. The reasons are the formation of electron pair donor–acceptor system in the film and the formation of double electrochromic effect. WO3/PB forms a rod-like nano core–shell structure, which increases the surface area for the reaction and facilitates the transfer of ions and electrons into and out of the film. This method of combining anodic electrochromic materials and cathodic electrochromic materials to form a core–shell structure to improve electrochromic performance provides a new direction for future electrochromic research. [ABSTRACT FROM AUTHOR]

Nano-WO3:EU3+ powder was prepared by Pechini method under acidic and alkaline condition, and the prepared acidic nano-WO3:Eu3+ mixed with the silver nanowires (AgNWs) in ethanol and acetone solution. The solution was mixed with PMMA and EP, respectively. Then, drops of the solutions were added to the indium tin oxide (ITO) conductive glass as the substrate; a AgNWs/WO3:Eu3+ composite film was obtained with spin coating by spin coater and solidification process. Microstructure, morphology, optical properties, preparation process and UV transmittance of the prepared nano-WO3:Eu3+ and AgNWs/WO3:Eu3+ composite films were investigated by XRD, SEM, fluorescence spectroscopy and UV spectrophotometer. The results show that the prepared acidic nano-WO3 is triclinic, and the average particle size is 71.63 nm. The prepared alkaline nano-WO3 is monoclinic, with an average particle size of 95.66 nm. Both of them have good luminescence properties. Under different monitoring wavelengths, in the emission range of 450–500 nm, it belongs to the green light region, and its excitation peak is the largest, indicating that green light is the best excitation light source for WO3:Eu3+ powder. The transmittance of EP/AgNWs/WO3:Eu3+ composite film is the highest when the spin coating time is more than 30 s and above 3000 rpm, no more than three layers spin coating and the content of curing agent is between 0.1 and 0.2 g. [ABSTRACT FROM AUTHOR]

As an electrochromic material, Co 3 O 4 has limited applications due to its low optical modulation range and short cycle life. In order to improve the electrochromic properties, a 1D/2D Co 3 O 4 /NiO composite film was prepared by simple two-step hydrothermal process and discontinuous annealing. The electrochromic properties of the composite structure are significantly improved compared with the nanostructures using two oxides alone. The effect of film structure on electrochromic properties was studied in detail. The results show that the 1D/2D Co 3 O 4 /NiO composite film have remarkable optical modulation (16–73% in the 350–800 nm range) and high Li+ diffusion rate (5.15 × 10−12 cm2/s). The improvement of electrochromic properties is mainly due to the porous structure, which increase the two active materials to leak fully in the electrolyte, thus enhancing the diffusion of ions and electrons. NiO nanosheets grow well and distribute uniformly on the surface of Co 3 O 4 nanowires, allowing the two parts to fully contact the electrolyte. Cyclic voltammetry (CV) analysis shows that the peak current of the composite film is much higher than that of the single film, indicating that the nanoarray has high electrochemical reactivity. Results of electrochemical impedance spectroscopy show that the composite film has the lower charge transfer resistance and ion diffusion resistance, which are conducive to rate capacity. This work provides a strategy for improving the electrochromic properties of cobaltosic oxide. [ABSTRACT FROM AUTHOR]

In this study, an all-solid-state electrochromic device (ECD) with the structure of ITO/WO 3 /Al 2 SiO 5 /NiO x /ITO was prepared, and the effect of the Al 2 SiO 5 solid electrolyte thicknesses on the opto-electrical performance was investigated. The microstructure and surface morphology were characterized using XRD, SEM and AFM, and the surface morphology and degree of surface looseness demonstrate a significant influence on the opto-electrical properties of ECDs. The charge transfer dynamics at the solid-solid interface were characterized using EIS to obtain an ionic conductivity of 4.637 × 10-8 S/cm. CV, CA and UV–Visible spectra were employed to record the in situ electrochemical and optical properties. The results revealed that the highest optical modulation was 44.58%, the coloring and bleaching times were 14.8 s and 3.7 s, and the highest coloring efficiency was 98.17 cm2/C, which indicates that excellent opto-electrical properties were obtained. When the thickness increases, the degree of surface dense morphology transforms, and the loose morphology is more favorable for ion conductivity, which improves the opto-electrical properties. The results in this study provide insights into the understanding of Al3+-based all-solid-state ECDs, which promote the exploration of new types of Al3+ ionic conductors for all-solid-state ECDs. [ABSTRACT FROM AUTHOR]

An electrochemical sensor based on the three-dimensional flower-like Fe3O4/Au porous microstructure to determine chloramphenicol (CAP) was successfully fabricated. This microstructure was synthesized hydrothermally with controlled reaction time in the presence of urea and decorated with Au nanoparticles via a simple chemical reduction method. The as-synthesized Fe3O4 and Fe3O4/Au porous microstructures were characterized by using scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy, elemental mapping, x-ray diffraction, nitrogen adsorption/desorption isotherms, UV–visible spectroscopy (UV–VIS), Fourier transform infrared spectroscopy, and electrochemical impedance spectroscopy. The electrochemical performance of the sensor was investigated with cyclic voltammetry and differential pulse voltammetry. The sensor exhibits excellent stability, reproducibility, and repeatability with a low CAP detection limit of 0.14 µM and a linear range of 1.0 to 12 µM. More importantly, it can be employed to determine chloramphenicol in the urine samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • An ether chain modified conjugated polymer was prepared in EtOH-CH 2 Cl 2 (v/v = 5/1). • Poly(EB-ether) achieves similar electrochromic parameters with that prepared in solvent containing large CH 2 Cl 2. Polar side chain plays an critical role in regulating molecular aggregation, film morphology and electrochromic properties of conjugated polymer. Here an ether chain modified conjugated polymer poly(EB-ether) based on EDOT and benzene was prepared at low oxidation potential by electrochemical method in EtOH-CH 2 Cl 2 (v/v = 5/1) containing 0.1 M Bu 4 NPF 6. The prepared poly(EB-ether) could achieve similar electrochromic parameters with alkoxy chain modified poly(EB-alkoxy), such as optical contrast of 35 %, response time of 0.8 s, coloration efficiency of 283 C−1 cm2, and reversible color change between dark red and blue. Electrochromic results indicate that high-performance poly(EB-ether) film could be prepared in mixed solvent containing little CH 2 Cl 2. Therefore, the introduction of ether chain in precursor is a feasible method to decrease or avoid the use of halogenated solvent in electrochemical polymerization process of precursor. [ABSTRACT FROM AUTHOR]

Pursuing to develop novel polymer-based electrode materials and explore their performance in electrochromic capacitive windows (ECWs), three polyamides containing propylenedioxythiophene (ProDOT) units were synthesized. The polymers were processed into thin coatings and subjected to rigorous structural and photophysical characterization, with focus on the electrochromic response and energy storage capability. One of the polymers showed electrochromic response with ultrafast color change (0.8 s for coloring) from highly transmissive yellow to deep green, opposite to most ProDOT-based materials that exhibit bleaching trends during oxidation, which is more convenient for smart glazing. A coloration efficiency of 358 cm2 × C−1, a maximum CE decay of 2.6 % after 100 cycles, and an excellent electrochromic stability, even up to 500 cycles was achieved for this material. In three-electrode cell configuration, this polymer revealed practical energy storage properties, including a wide voltage window, a good capacitance, of 5.63 mF × cm−2, and an outstanding electrochemical cycling durability. Therefore, a prototype polyamide based-ECW device was built and its overall performance was explored. Due to the well capability of this polymer to simultaneously operate as a smart color changing and energy storage electrode, it can be considered as promising material for use in energy storage smart windows with potential applications in green-enabling technologies. • Three polyamides containing propylenedioxythiophene (ProDOT) units are synthesized. • The polymers display thermal stability up to 270 °C and CT blue/green fluorescence. • The polymers containing only ProDOT provide low capacitance and no electrochromism. • TPA- and ProDOT-based polyamide undergoes ultrafast color switch while stores energy. • An ECW is realized enabling smart monitoring of the energy level stored in the device. [ABSTRACT FROM AUTHOR]

Carbazole and triphenylamine derivatives have become popular research topics in the field of electrochromism and electrofluorochromic due to their excellent reversible oxidative activity, reversible colour change and reversible fluorescence change during electrochemical processes. Four asymmetric carbazole-triphenylamine derivatives 6a-d were designed and synthesized. Both ultraviolet absorption (UV) spectra and fluorescence emission (PL) spectra changed with the change in voltage applied to all compounds. These compounds were fabricated into electrochromic and electrofluorochromic devices, and these devices exhibited excellent cycling stability (cycling stability remains above 95% after 11000 s), short switching time (1.1 s ∼ 1.6 s), high PL contrast (146 ∼ 172), and high colour contrast (47.2% ∼ 50.6%). All the samples fluoresced off in the oxidised state and exhibited alternating yellow-green characteristics, and fluoresced on in the reduced state while exhibiting a highly transparent and colourless state. The experimental results indicated that these materials are expected to be used for the preparation of wearable devices and transparent displays. The research demonstrated that rich color changes can be achieved by adjusting the electrochemical properties of dual redox centered materials. [Display omitted] • The asymmetric structure can improve the luminescence efficiency of the devices. • The dual redox centres can enrich the device colours. • Devices 6a-d were highly transparent and colourless in the pristine neutral state. • Devices 6a-d have high colour contrast and excellent stability. [ABSTRACT FROM AUTHOR]

We reported four colorless V-shaped triphenylamine-based monomers MMTPA , MFTPA , FMTPA and FFTPA and their electrochemical polymerizations for multicolor electrochromic energy storage devices. [Display omitted] • Four colorless conjugated polymers were developed for electrochromic and energy storage devices. • The present polymers showed multicolor electrochromism from colorless to orange, and further to blue. • PMMTPA showed a high specific capacitance up to 23.1 mF cm−2 at the current density of 0.1 mA cm−2. Four V-shaped monomers (MMTPA , MFTPA , FMTPA , FFTPA) consisting of two triphenylamine units located on the 4,5-positions of the imidazole-based π-spacers were prepared by one-pot condensation reaction, and further deposited on ITO substrates by electrochemical polymerizations for electrochromism and energy storage. The present polymers (PMMTPA , PMFTPA , PFMTPA , PFFTPA) exhibited efficient multicolor colorless-to-orange-to-blue electrochromism, involving large optical contrast over 60 %, short response time less than 3 s, high coloration efficiency over 190 mC·cm−2, as well as good switching stability. Additionally, all these triphenylamine-based polymer thin films exhibited high area ratio capacitance over 6 mF cm−2 at the current density of 0.1 mA cm−2. The electrochromic energy storage devices based on these polymers were fabricated and could light the LED bulb with visualizing the energy storage state, which guaranteed their potential applications in energy saving smart windows. [ABSTRACT FROM AUTHOR]

We reported two butterfly-shaped monomers TTCQF and TTCQH consisting of camphor-substituted quinoxaline units as π-spacers, and their electrochemical polymerizations for electrochromic energy storage devices. [Display omitted] • Two conjugated polymers PTTCQH and PTTCQF were developed for electrochromic and energy storage devices. • The present polymers showed efficient electrochromic performance with large optical contrast over 75 % around 1100 nm. • PTTCQH exhibited large areal specific capacitance of 12 mF/cm2 at a current density of 0.1 mA/cm2. Two new butterfly-shaped monomers TTCQF and TTCQH consisting of camphor-substituted quinoxaline units as π-spacers were designed and synthesized, which were further electrochemical polymerized and deposited on ITO substrates for electrochromic energy storage devices. The present cross-linked polymer thin films PTTCQF and PTTCQH displayed prominent color changes with significant optical contrast in both the visible and near-infrared regions under external electrical stimuli. These two polymers showcased superior electrochromic performance, involving high optical contrast, fast switching speed, and good coloration efficiency. Additionally, both polymers demonstrated a high areal specific capacitance (12 mF/cm2 for PTTCQH and 9.97 mF/cm2 for PTTCQF) at a current density of 0.1 mA/cm2. Electrochromic energy storage devices based on these polymers were fabricated, and not only illuminated an LED bulb but also visually indicated the energy storage state, guaranteed their potential for applications in energy-saving smart windows. This work may provide valuable insights into the development of efficient cross-linked electrochromic energy storage polymers. [ABSTRACT FROM AUTHOR]

Bredereck oxazole synthesis was utilized to create a series of novel D-A polymers based on the triphenylamine (TPA) derivative, 4,4′-Diformyltriphenylamine (DPA), 4,4′-((4-bromophenyl)azanediyl)dibenzaldehyde (BPA), and oxamide/dithiooxamide. The obtained novel polymers exhibited impressive solution processabilities and excellent thermal stabilities. In the entire processes of electrochemical oxidation, these polymer films exhibited excellent electrochromic (EC) performances, high optical contrasts (49.6–52.8 %), high coloration efficiencies (362–451 cm2·C−1), and excellent cycling stabilities (18.6–33.9 % decay) with a cycle time of 20 s. By applying voltage, electrofluorochromic (EFC) performance can also be adjusted. Furthermore, these polymers showed fluorescence (PL) in solvents and solvatochromic effects in absorption. The outcome was indicative of the addition of oxazole[5,4- d ]oxazoles (OzOz) and thiazolo[5,4- d ]thiazoles (TzTz), whose highly conjugate rigid planar structures can significantly increase molecule stabilities and minimizing volume shrinking during charge transfer. In addition, due to introducing bromine atoms, the p-π conjugations enhanced the conjugation degrees of the molecules, which facilitated the electron transfers. Experimental results show that these improvement schemes will pave a way for obtaining multi-function optoelectronic devices with long-term cyclic stabilities. [Display omitted] • The electrochromic stability was optimized by introducing TzTz-type/OzOz-type group to the polymers. • Polymers were synthesized using fewer steps and cheap raw materials. • The introduction of fluorescent chromophore the fluorescence properties of the polymer and increased their potential purposes. [ABSTRACT FROM AUTHOR]