Showing papers on "Electrochromism published in 2021"

Pressure-Based Biosensor Integrated with a Flexible Pressure Sensor and an Electrochromic Device for Visual Detection.

Abstract: This work demonstrated a pressure-based biosensor integrated with a flexible pressure sensor and an electrochromic device for visual detection. Initially, a sandwich-type immunoreaction for target carcinoembryonic antigen (CEA, as a model analyte) was carried out using the capture antibody (cAb) and platinum nanoparticles-labeled detection antibody (PtNPs-dAb) in a reaction cell. The added hydrogen peroxide (H2O2) could be catalyzed by the PtNPs to generate oxygen (O2). In a sealed chamber, the pressure increased with the overflowing O2. Meanwhile, a skin-inspired flexible pressure sensor with excellent sensing performance was fabricated to monitor the pressure change in real time. Thus, the electrical signal of the pressure sensor could reveal the target concentration. Moreover, a voltage-regulated electrochromic device based on polyaniline (PANI) and tungsten oxide (WO3) was integrated into the platform to provide a visualized readout. According to the electrical signal of the pressure sensor, the electrochromic device would change its color from green to blue, which also revealed the target concentration and could be observed by the naked eye. Under optimal conditions, the biosensor presented a high sensitivity for CEA in a detectable range of 0.2-50 ng/mL. The limit of detection (LOD) was 94 pg/mL. The selectivity, reproducibility, and accuracy were also satisfying. Furthermore, this immunoassay gives a path for developing visualized biosensors in point-of-care settings.

Flexible and high-performance electrochromic devices enabled by self-assembled 2D TiO2/MXene heterostructures.

Abstract: Transition metal oxides (TMOs) are promising electrochromic (EC) materials for applications such as smart windows and displays, yet the challenge still exists to achieve good flexibility, high coloration efficiency and fast response simultaneously. MXenes (e.g. Ti3C2Tx) and their derived TMOs (e.g. 2D TiO2) are good candidates for high-performance and flexible EC devices because of their 2D nature and the possibility of assembling them into loosely networked structures. Here we demonstrate flexible, fast, and high-coloration-efficiency EC devices based on self-assembled 2D TiO2/Ti3C2Tx heterostructures, with the Ti3C2Tx layer as the transparent electrode, and the 2D TiO2 layer as the EC layer. Benefiting from the well-balanced porosity and connectivity of these assembled nanometer-thick heterostructures, they present fast and efficient ion and electron transport, as well as superior mechanical and electrochemical stability. We further demonstrate large-area flexible devices which could potentially be integrated onto curved and flexible surfaces for future ubiquitous electronics.

Automatic light-adjusting electrochromic device powered by perovskite solar cell

Abstract: Electrochromic devices can modulate their light absorption under a small driving voltage, but the requirement for external electrical supplies causes response-lag To address this problem, self-powered electrochromic devices have been studied recently However, insensitivity to the surrounding light and unsatisfactory stability of electrochromic devices have hindered their critical applications Herein, novel perovskite solar cell-powered all-in-one gel electrochromic devices have been assembled and studied in order to achieve automatic light adjustment Two alkynyl-containing viologen derivatives are synthesized as electrochromic materials, the devices with very high stability (up to 70000 cycles) serves as the energy storage and smart window, while the perovskite solar cell with power-conversion-efficiency up to 183% serves as the light detector and power harvester The combined devices can automatically switch between bleached and colored state to adjust light absorption with variable surrounding light intensity in real-time swiftly, which establish significant potentials for applications as modern all-day intelligent windows

Fast-Switching Vis–IR Electrochromic Covalent Organic Frameworks

Abstract: Electrochromic coatings are promising for applications in smart windows or energy-efficient optical displays. However, classical inorganic electrochromic materials such as WO3 suffer from low color...

Self-Powered Flexible Electrochromic Smart Window

Abstract: Electrochromic devices have attracted considerable interest for smart windows. However, current development suffers from the requirement of the external power sources and rigid ITO substrate, which not only causes additional energy consumption but also limits their applications in flexible devices. Inspired by galvanic cell, we demonstrate a self-powered flexible electrochromic device by integrating Ag/W18O49 nanowire film with the Al sheet. The Ag nanowire film first acted as the electrode to replace the ITO substrate, then coupled with the Al sheet to induce an open-circuit voltage of ∼0.83 V, which is high enough to drive the coloration of W18O49 nanowires. Remarkably, the flexible self-powered electrochromic device only expends ∼6.8 mg/cm2 of the Al sheet after 450 electrochromic switching cycles and the size can be easily expanded with an area of 20 × 20 cm2, offering significant potential applications for the next generation of flexible electrochromic smart window.

Super-stretchable and extreme temperature-tolerant supramolecular-polymer double-network eutectogels with ultrafast in situ adhesion and flexible electrochromic behaviour

Abstract: The current tough and stretchable gels with various integrated functions are mainly based on polymer hydrogels. By introducing a non-covalent supramolecular self-assembled network into a covalently cross-linked polymer network in the presence of eco-friendly and cost-effective deep eutectic solvents (DESs), we developed a new small molecule-based supramolecular-polymer double-network (SP-DN) eutectogel platform. This exciting material exhibits high stretchability and toughness (>18 000% areal strain), spontaneous self-healing ability, ultrafast (∼5 s) in situ underwater and low-temperature (−80 °C) adhesion, and unusual boiling water-resistance, as well as strong base-, strong acid- (even aqua regia), ultra-low-temperature- (liquid nitrogen, −196 °C), and high-temperature- (200 °C) resistance. All these outstanding properties strongly recommend the SP-DN eutectogels as a quasi-solid electrolyte for soft electrochromic devices, which exhibited exceptional flexibility and consistent electrochromic behaviours in harsh mechanical or temperature environments. The experimental and simulation results uncovered the assembly mechanism of the SP-DN eutectogels. Unlike polymer hydrogels, the obtained SP-DN eutectogels showed high molecular design freedom and structural versatility. The findings of this work offer a promising strategy for developing the next generation of mechanically robust and functionally integrated soft materials with high environmental adaptability.

Nickel Cobalt Oxide Nanoneedles for Electrochromic Glucose Sensors

Abstract: Uniform nanoneedles of binary oxide (Ni and Co) were synthesized on appropriate conducting substrates [fluorine-doped tin oxide (FTO) coated glass and carbon cloth (CC)] and investigated for dual a...

A Covalent Organic Framework Film for Three‑State Near‑Infrared Electrochromism and a Molecular Logic Gate

Abstract: A Kagome structure covalent organic framework (COF) film with three-state near-infrared (NIR) electrochromic properties was designed and synthesized. The morphology and structure characterization revealed that the COFTPDA-PDA film was composed of hexagonal nanosheets with high crystallinity. The COFTPDA-PDA film exhibit three reversible color states at different applied potentials, and high absorption spectra changes in the NIR region, which can be ascribed to the strong intervalence charge transfer (IVCT) interaction of the Class III mixed-valence systems of the conjugated triphenylamine species. The COFTPDA-PDA film showed the sub-second response time (1.3 s for coloring and 0.7 s for bleaching at 1050 nm) and the long retention time in the NIR region. In comparison with the amorphous film with the same monomers, COFTPDA-PDA film show superior NIR electrochromic properties in term of response time and stability, which could be attributed to the highly ordered porous structure and the π-π stacking structure of the COFTPDA-PDA architecture. Furthermore, the COFTPDA-PDA film was successfully applied in mimicking flip-flop logic gate with optical memory functions.

Reversible Zn2+ Insertion in Tungsten Ion-Activated Titanium Dioxide Nanocrystals for Electrochromic Windows.

Abstract: Zinc-anode-based electrochromic devices (ZECDs) are emerging as the next-generation energy-efficient transparent electronics. We report anatase W-doped TiO2 nanocrystals (NCs) as a Zn2+ active electrochromic material. It demonstrates that the W doping in TiO2 highly reduces the Zn2+ intercalation energy, thus triggering the electrochromism. The prototype ZECDs based on W-doped TiO2 NCs deliver a high optical modulation (66% at 550 nm), fast spectral response times (9/2.7 s at 550 nm for coloration/bleaching), and good electrochemical stability (8.2% optical modulation loss after 1000 cycles).

Mimicking Nature's Butterflies: Electrochromic Devices with Dual-Sided Differential Colorations.

Abstract: Some butterfly species such as the orange oakleaf (Kallima inachus) have strikingly different colors on the dorsal (front) sides of their wings compared to those on the ventral (back) sides of their wings, which helps camouflage the butterflies from predators and attract potential mates. However, few human-made materials, devices, and technologies can mimic such differential coloring for a long time. Here, a new type of Janus-structured two-sided electrochromic device is developed that, upon application of different voltages, exhibits a coloration state on one side that is distinctly different from that on the other side. This is achieved by inserting an optically thin (4-8 nm) metallic layer with a complex refractive index, such as a layer composed of tungsten, titanium, copper or silver, into typical electrochromic structures.

A Review on the Properties and Applications of WO3 Nanostructure-Based Optical and Electronic Devices.

Abstract: Tungsten oxide (WO3) is a wide band gap semiconductor with unintentionally n−doping performance, excellent conductivity, and high electron hall mobility, which is considered as a candidate material for application in optoelectronics. Several reviews on WO3 and its derivatives for various applications dealing with electrochemical, photoelectrochemical, hybrid photocatalysts, electrochemical energy storage, and gas sensors have appeared recently. Moreover, the nanostructured transition metal oxides have attracted considerable attention in the past decade because of their unique chemical, photochromic, and physical properties leading to numerous other potential applications. Owing to their distinctive photoluminescence (PL), electrochromic and electrical properties, WO3 nanostructure−based optical and electronic devices application have attracted a wide range of research interests. This review mainly focuses on the up−to−date progress in different advanced strategies from fundamental analysis to improve WO3 optoelectric, electrochromic, and photochromic properties in the development of tungsten oxide−based advanced devices for optical and electronic applications including photodetectors, light−emitting diodes (LED), PL properties, electrical properties, and optical information storage. This review on the prior findings of WO3−related optical and electrical devices, as well as concluding remarks and forecasts will help researchers to advance the field of optoelectric applications of nanostructured transition metal oxides.

Multicolor and Multistage Response Electrochromic Color-Memory Wearable Smart Textile and Flexible Display.

Abstract: Electrochromic materials have great application in soft displays and devices, but the application of ideal electrochromic textiles still faces challenges owing to the inconvenience of a continuous power supply. Here, electrochromic color-memory microcapsules (ECM-Ms-red, -yellow, and -blue) with a low drive voltage (2.0 V), coloration efficiency (921.6 cm2 C-1), a practical response rate (34.4 s-1), multistage response discoloration, and good color-memory performance (>72 h) and reversibility (≥1000 cycles) are developed. The color-memory performance is controlled by the energy difference of oxidation-reduction reactions. A multicolor and multistage response electrochromic color-memory wearable smart textile and flexible display are developed that are convenient and energy-efficient for application. The design philosophy of color-memory based on controllable energy difference of reactions has great potential application in sensors and smart textiles.

A rechargeable electrochromic energy storage device enabling effective energy recovery

Abstract: Efficient energy recovery from electrochromic (EC) devices gives new insight into reducing the consumption of energy and facilitating the recycling of energy. However, one challenge is to realize the effective energy storage and conversion without sacrificing the electrochromic performance. Herein, spinel Li4Ti5O12 (LTO), a desirable anodic material for lithium ion batteries, was employed to develop a rechargeable electrochromic energy storage device (EESD), instead of utilizing conventional capacitive EC materials. Moreover, the LTO film exhibited a good electrochromic performance in terms of visible and near-infrared transmittance modulation (54.9% at 550 nm and 71.6% at 1000 nm), indicating that it can effectively block 90% of the thermal radiation energy in the sunlight. In addition to its high theoretical capacity and excellent structural stability, LTO displayed a large optical contrast during energy storage and conversion, and its EC mechanism was further revealed by analyzing its electronic structure evolution in response to lithiation based on density functional theory calculations. When assembled with a complementary EC NiO anode, the well-designed LTO-based EESD demonstrated a reversible transmittance variation over 50% between charged (colored) and discharged (bleached) states. For energy storage, the rechargeable EESD with a high operating voltage of 3.0 V could power a 1.7 V red light-emitting diode (LED) for more than 10 min and provide an energy density of 0.2 W h cm−3, which is superior to most state-of-the-art energy storage systems based on conventional EC materials. As a proof of concept, EESD is designed to be a prototype device of smart window to elucidate the feasibility for energy recovery and self-power applications. The energy used to drive the coloring of the EESD window could be stored on a sunny day and then power a household lamp (3 V/5 W) at night. It is envisioned that the rechargeable EESD in this work will provide an applicable platform for effective energy recovery in real-world applications involving advanced energy technology and smart window architecture.