Electrochromic and Energy Storage Performance Enhancement by Introducing Jahn-Teller Distortion: Experimental and Theoretical Study.

Aqueous electrochromic batteries (ECBs) have recently garnered significant attention within the realm of renewable rechargeable technology due to their potential applicability in diverse multifunctional devices featuring visible-level indicator batteries. However, there exists an imperative to comprehend the underlying structural factors that contribute to achieving an elevated electrochemical performance. In this context, we have synthesized and compared WO3·H2O (HWO) specifically for heightened ECB application as against the performance of a standard anhydrous WO3 (AWO). To unravel the underlying cause, a density functional theory (DFT) investigation is carried out, disclosing a structural deformation of HWO, unlike AWO, due to Jahn-Teller distortion induced by the presence of interlayer water. It results in a fully compatible HWO ion host to devise a zinc-ion aqueous electrolyte electrochromic battery, exhibiting superior redox reactivity, optical modulation (50%), capacity (200 mAh/m2), and cyclic stability. To glean insights into the dynamic structural alterations during the intercalation and deintercalation processes of Zn2+, ex situ X-ray diffraction and Raman spectroscopic studies are carried out. These investigations culminate in the determination that HWO films are better suited for the application than their AWO counterparts. This finding holds promise for advancing the applications of ECBs and represents a significant step forward in this field.

Self-Sustaining Triboelectric Nanosensors for Real-Time Urine Analysis in Smart Toilets.

Healthcare has undergone a revolutionary shift with the advent of smart technologies, and smart toilets (STs) are among the innovative inventions offering non-invasive continuous health monitoring. The present technical challenges toward this development include limited sensitivity of integrated sensors, poor stability, slow response and the requirement external energy supply alongside manual sample collection. In this article, triboelectric nanosensor array (TENSA) is introduced featuring electrodes crafted from laser-induced 3D graphene with functional polymers like polystyrene, polyimide, and polycaprolactone for real-time urine analysis while generating 50 volts output via urine droplet-based triboelectrification. Though modulating interfacial double-layer capacitance, these sensors exhibit exceptional sensitivity and selectivity in detecting a broad spectrum of urinary biomarkers, including ions, glucose, and urea with a classification precision of 95% and concentration identification accuracy of up to 0.97 (R2), supported by artificial neural networks. Upon exposure to urine samples containing elevated levels of Na+, K+, and NH4 +, a notable decrease (ranging from 32% to 68%) is observed in output voltages. Conversely, urea induces an increase up to 13%. Experimental validation confirms the stability, robustness, reliability, and reproducibility of TENSA, representing a significant advancement in healthcare technology, offering the potential for improved disease management and prevention strategies.

Te4+ and Er3+ doped ZrO2 nanoparticles with enhanced photocatalytic, antibacterial activity and dielectric properties: A next generation of multifunctional material.

Amid rising water contamination from industrial sources, tackling toxic dyes and pathogens is critical. Photocatalysis offers a cost-effective and eco-friendly solution to this pressing challenges. Herein, we synthesized Te4+ and Er3+ doped ZrO2 photocatalysts through hydrothermal method and investigated their efficacy in degrading Congo red (CR) and pathogens under visible light. XRD and Raman Spectroscopy confirm monoclinic and tetragonal mixed-phases without any impurities. Doping-induced defects, reduced crystalline diameter, high surface area, modified bandgap (2.95 eV), photoluminescence quenching, coupled with interfacial polarization, contribute to EZO's excellent dielectric response (1.149 × 106), for achieving remarkable photocatalytic activity, verified by photoelectrochemical measurements, LC-MS and phytotoxicity analysis. Under optimal conditions, EZO achieves 99% CR degradation within 100 min (TOC 79.9%), surpassing ZO (77%) and TZO (84%). Catalyst dosages, dye concentrations, and solution pH effect on EZO's photocatalytic performance are systematically assessed. Scavenging experiment emphasized the pivotal role of · OH in CR degradation with 96.4% efficiency after 4 cycles, affirming its remarkable stability. Moreover, EZO demonstrates ROS-mediated antibacterial activity against E. faecalis and E. coli bacteria under visible light, achieving >97% and >94% inhibition rate with an inhibition zone > 3 mm. Hence, the nanoparticle's dual action offers a practical solution for treating contaminated wastewater, ensuring safe irrigation.

Sonochemically synthesized black phosphorus nanoparticles: a promising candidate for piezocatalytic antibacterial activity with enhanced dielectric properties.

The drawbacks inherent to traditional antibacterial therapies, coupled with the escalating prevalence of multi-drug resistant (MDR) microorganisms, have prompted the imperative need for novel antibacterial strategies. Accordingly, the emerging field of piezocatalysis in semiconductors harnesses mechanical stress to drive chemical reactions by utilizing piezo-generated free charge carriers, presenting a promising technology. To the best of our knowledge, this study is the first to provide a comprehensive overview of the eradication of pathogenic S. aureus bacteria using few-layer black phosphorus (SCBP) piezo catalyst under mechanical stimuli, along with the exploration of temperature dependent dielectric properties. The synthesis of the piezo catalysts involved a one-step cost-effective sonochemical method, and its structural, morphological, elemental, optical, and overall polarization properties were thoroughly characterized and compared with the traditional method-derived product (TABP). The synthesis-introduced defects, reduced crystalline diameters, modified bandgap (1.76 eV), nanoparticle aggregation, photoluminescence quenching, along with interfacial polarization, synergistically contribute to SCBP's exceptional dielectric response (4.596 × 107 @40 Hz), which in turn enhanced the piezocatalytic activity. When subjected to soft ultrasound stimulation at 15 kHz, the piezo catalyst SCBP demonstrated significant ROS-mediated antibacterial activity, resulting in a ∼94.7% mortality rate within 40 minutes. The impact of this study extends to cost-effective energy storage devices and advances in antibacterial therapy, opening new dimensions in both fields.

Ambient stable solution-processed organic field effect transistors from electron deficient planar aromatics: effect of end-groups on ambient stability.

Ambient stable solution processed n-channel organic field effect transistors (OFETs) are essential for next-generation low-cost organic electronic devices. Several molecular features, such as suitable orbital energy levels, easy synthetic steps, etc., must be considered while designing efficient active layer materials. Here, we report a case of improved ambient stability of solution-processed n-type OFETs upon suitable end-groups substitution of the active layer materials. A pair of core-substituted napthalenediimide (NDIFCN2 and EHNDICN2) derivatives with alkyl and perfluorinated end groups are considered. The transistor devices made out of these two derivatives exhibited largely different ambient stability behavior. The superior device stability (more than 25 days under ambient conditions) of one of the derivatives (NDIFCN2) was ascribed to the presence of fluorinated end groups that function as hydrophobic guard units inhibiting moisture infiltration into the active layer, thereby achieving ambient stability under humid conditions (>65% relative atmospheric humidity). Molecular level optical and electrochemical properties, thermal stability, and the solution-processed (spin coat and drop cast active layers) device characteristics are described in detail. Our findings highlight the requirement of hydrophobic end groups or sidechains for ambient stability of active layer materials, along with deep LUMO levels for ambient stability.

Neuromorphic devices realised using self-forming hierarchical Al and Ag nanostructures: towards energy-efficient and wide ranging synaptic plasticity.

Closely mimicking the hierarchical structural topology with emerging behavioral functionalities of biological neural networks in neuromorphic devices is considered of prime importance for the realization of energy-efficient intelligent systems. In this article, we report an artificial synaptic network (ASN) comprising of hierarchical structures of isolated Al and Ag micro-nano structures developed via the utilization of a desiccated crack pattern, anisotropic dewetting, and self-formation. The strategically designed ASN, despite having multiple synaptic junctions between electrodes, exhibits a threshold switching (Vth ∼ 1-2 V) with an ultra-low energy requirement of ∼1.3 fJ per synaptic event. Several configurations of the order of hierarchy in the device architecture are studied comprehensively to identify the importance of the individual metallic components in contributing to the threshold switching and energy-minimization. The emerging potentiation behavior of the conductance (G) profile under electrical stimulation and its permanence beyond are realized over a wide current compliance range of 0.25 to 300 µA, broadly classifying the short- and long-term potentiation grounded on the characteristics of filamentary structures. The scale-free correlation of potentiation in the device hosting metallic filaments of diverse shapes and strengths could provide an ideal platform for understanding and replicating the complex behavior of the brain for neuromorphic computing.

Dual-Functional Electrochromic Smart Window Using WO3·H2O-rGO Nanocomposite Ink Spray-Coated on a Low-Cost Hybrid Electrode.

Electrochromic windows have gained growing interest for their ability to change their optical state in the visible and NIR ranges with minimal input power, making them energy-efficient. However, material processing costs, fabrication complexity, and poor electrochromic properties can be barriers to the widespread adoption of this technology. To address these issues, electrochromic material and fabrication processes are designed to realize their potential as a cost-effective and energy-efficient technology. In this work, an electrochromic composite material-based ink is synthesized consisting of WO3·H2O nanoplates supported on rGO (reduced graphene oxide) nanosheets (WH-rGO), wherein an optimized amount of rGO (0.05 to 0.5 wt %) is introduced for providing a higher conduction pathway for efficient charge transport without sacrificing the electrochromic performance of WO3·H2O nanoplates. The stable ink dispersion prepared in the study is deposited by spray coating on transparent conducting electrodes over large areas (25 cm2). The WH-rGO nanocomposite (0.4 wt %) results in 43% optical modulation at 700 nm, with bleaching and coloration times of 6 and 8 s, respectively. Interestingly, the device also possesses an electrochemical energy storage capability with an areal capacitance of 16.3 mF/cm2. The electrochromic composite material is successfully translated on tin doped indium oxide (ITO)-coated Al metal mesh hybrid electrodes (T = 80%, Rs = 40 Ω/□) to replace ITO. Finally, an electrochromic device of 5 × 5 cm2 is fabricated by spray-coating the ink on cost-effective ITO/Al-mesh hybrid electrodes. The device displays blue to colorless modulation with an excellent bleaching time of 0.43 s and a coloration time of 2.16 s, making it one among the fast-operating devices fabricated by complete solution processing. This work showcases the economical production of a dual-function electrochromic device, which can be a feasible option as an alternative to existing ITO-based devices in both automotive and infrastructure applications.

A scalable solution recipe for a Ag-based neuromorphic device.

Integration and scalability have posed significant problems in the advancement of brain-inspired intelligent systems. Here, we report a self-formed Ag device fabricated through a chemical dewetting process using an Ag organic precursor, which offers easy processing, scalability, and flexibility to address the above issues to a certain extent. The conditions of spin coating, precursor dilution, and use of solvents were varied to obtain different dewetted structures (broadly classified as bimodal and nearly unimodal). A microscopic study is performed to obtain insight into the dewetting mechanism. The electrical behavior of selected bimodal and nearly unimodal devices is related to the statistical analysis of their microscopic structures. A capacitance model is proposed to relate the threshold voltage (Vth) obtained electrically to the various microscopic parameters. Synaptic functionalities such as short-term potentiation (STP) and long-term potentiation (LTP) were emulated in a representative nearly unimodal and bimodal device, with the bimodal device showing a better performance. One of the cognitive behaviors, associative learning, was emulated in a bimodal device. Scalability is demonstrated by fabricating more than 1000 devices, with 96% exhibiting switching behavior. A flexible device is also fabricated, demonstrating synaptic functionalities (STP and LTP).

Emulating learning behavior in a flexible device with self-formed Ag dewetted nanostructure as active element.

Neuromorphic devices are a promising alternative to the traditional von Neumann architecture. These devices have the potential to achieve high-speed, efficient, and low-power artificial intelligence. Flexibility is required in these devices so that they can bend and flex without causing damage to the underlying electronics. This feature shows a possible use in applications that require flexible electronics, such as robotics and wearable electronics. Here, we report a flexible self-formed Ag-based neuromorphic device that emulates various brain-inspired synaptic activities, such as short-term plasticity and long-term potentiation (STP and LTP) in both the flat and bent states. Half and full-integer quantum conductance jumps were also observed in the flat and bent states. The device showed excellent switching and endurance behaviors. The classical conditioning could be emulated even in the bent state.

Fabrication of Large-Area, Affordable Dual-Function Electrochromic Smart Windows by Using a Hybrid Electrode Coated with an Oxygen-Deficient Tungsten Oxide Ultrathin Porous Film.

Electrochromic (EC) devices are not commercialized extensively owing to their high cost. The best large-area devices in the market suffer from not reaching a distinct dark-colored state. These devices appear more like a blue tinted glass. While a better performance demands the use of appropriate components, the cost-effectiveness of such components is crucial for commercialization. Specifically, the utilization of cost-effective electrodes, thin WO3 coatings, and inexpensive electrolytes are essential for reducing the cost of EC devices. Here, we report a high-performing porous WO3 thin film (∼130 nm) achieved by optimizing the DC sputtering process parameters. This way, an affordable dual-function EC energy-storage device was fabricated, showing 84% transmittance modulation and a high power density of 3036 mW/m2, thus functioning simultaneously as a transparency switching energy-storage device. With a large-area (900 cm2) device, we have demonstrated that the need for expensive ITO electrodes and Li+ ion-based electrolytes can be eliminated by using a hybrid electrode (ITO/Al-mesh) and multivalent Al3+ ion-based electrolytes while not compromising the device performance. The findings of this study may revolutionize the EC device industry and their commercialization owing to inexpensive ingredients and scalable processing.

Cost-Effective Smart Window: Transparency Modulation via Surface Contact Angle Controlled Mist Formation.

Implementing simple and inexpensive energy-saving smart technologies in households is quite effective to accomplish on-demand privacy control and reduction in energy consumption. Conventional smart glasses face difficulty in making inroads into the consumer market due to utilizing expensive active layers, electrolytes, and transparent electrodes. Thus, the need of the hour is to develop an unconventional smart window, which should be cost-effective, power-efficient, and simple to fabricate. Against this backdrop, we report the fabrication of a new class of smart partition windows termed "mist-driven transparency switching glass". The fabrication protocol includes surface energy modification of two glass panes, followed by assembling them into a square or rectangular-shaped narrow cell with appropriate inlets and outlets for mist. In its pristine state, the device is transparent, as expected of two plain glasses forming a cell. Insertion of cool mist into the device produces tiny droplets onto the inner walls due to condensation enabling scattering of light, thereby producing the translucent state. The optimized device shows a transmittance modulation of as much as ∼65% at 550 nm, allowing it to reduce the indoor temperature by more than 30% compared to a regular glass windowpane. To realize commercial viability, a large area device (30 × 30 cm2) was fabricated, which could be operated wirelessly through a cellphone application paving the way for incorporating the Internet of Things into the technology.

Scalable Fabrication of Scratch-Proof Transparent Al/F-SnO2 Hybrid Electrodes with Unusual Thermal and Environmental Stability.

Fabrication protocols of transparent conducting electrodes (TCEs), including those which produce TCEs of high values of figure of merit, often fail to address issues of scalability, stability, and cost. When it comes to working with high-temperature stable electrodes, one is left with only one and that too, an expensive choice, namely, fluorine-doped SnO2 (FTO). It is rather difficult to replace FTO with a low-cost TCE due to stability issues. In the present work, we have shown that an Al nanomesh fabricated employing the crack template method exhibits extreme thermal stability in air even at 500 °C, compared with that of FTO. In order to fill in the non-conducting island regions present in between the mesh wires, a moderately conducting material SnO2 layer was found adequate. The innovative step employed in the present work relates to the SnO2 deposition without damaging the underneath Al, which is a challenge in itself, as the commonly used precursor, SnCl2 solution, is quite corrosive toward Al. Optimization of spray coating of the precursor while the Al mesh on a glass substrate held at an appropriate temperature was the key to form a stable hybrid electrode. The resulting Al/SnO2 electrode exhibited an excellent transparency of ∼83% at 550 nm and a low sheet resistance of 5.5 Ω/□. SnO2 coating additionally made the TCE scratch-proof and mechanically stable, as the adhesion tape test showed only 8% change in sheet resistance after 1000 cycles. Further, to give FTO-like surface finish, the SnO2 surface was fluorinated by treating with a Selectfluor solution. As a result, the Al/F-SnO2 hybrid film exhibited one order higher surface conductivity with negligible sensitivity toward humidity and volatile organics, while becoming robust toward neutral electrochemical environments. Finally, a custom-designed projection lithography technique was used to pixelate the Al/SnO2 hybrid film for optoelectronic device applications.

Innovative Approach to Photo-Chemiresistive Sensing Technology: Surface-Fluorinated SnO2 for VOC Detection.

Transparent electronics continues to revolutionize the way we perceive futuristic devices to be. In this work, we propose a technologically advanced volatile organic compound (VOC) sensor in the form of a thin-film transparent display fabricated using fluorinated SnO2 films. A solution-processed method for surface fluorination of SnO2 films using Selectfluor as a fluorinating agent has been developed. The doped fluorine was optimized to be <1%, resulting in a significant increase in conductivity and reduction in persistent photoconductivity accompanied by a faster decay of the photogenerated charge carriers. A combination of these modified properties, together with the intrinsic sensing ability of SnO2, was exploited in designing a transparent display sensor for ppm-level detection of VOCs at an operating temperature of merely 150 °C. Even a transparent metal mesh heater is integrated with the sensor for ease of operation, portability, and less power usage. A sensor reset method is developed while shortening the UV exposure time, enabling complete sensor recovery at low operating temperatures. The sensor is tested toward a variety of polar and nonpolar VOCs (amines, alcohols, carbonyls, alkanes, halo-alkanes, and esters), and it exhibits an easily differentiable response with sensitivity in line with the electron-donating tendency of the functional group present. This work opens up the door for multiplexed sensor arrays with the ability to detect and analyze multiple VOCs with specificity.