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In this work, stearic acid (SA) was used to improve the dispersion and tribological performance of graphene oxide (GO). The results exhibited that the SA could improve the dispersion of GO in water by the typical steric hindrance effect. As water-based lubricating additives, the GO modified by SA showed good tribological performance and load-carrying capacity, which had a low coefficient of friction and no obvious wear scar even sliding under the load of 400 mN for 2 h, indicating a long lubricating life. These superior performances were ascribed to the good dispersion of SA-modified GO in water and the synergistic effect of the excellent anti-wear property of GO and the good lubricating performance of SA. [ABSTRACT FROM AUTHOR]

The additive strategy has emerged as an effective approach to improving the performance of perovskite solar cells (PSCs). Herein, a small acceptor-donor-acceptor type molecule indaceno[1,2-b:5,6-b′]dithiophene chloride (IDT-Cl) is designed and synthesized to advance both the efficiency and stability of FA0.85MA0.15PbI3 PSCs. Within the IDT-Cl molecule, the S-group with high electron density promotes chemical bonding with the lead cations in the perovskite, resulting in enlarged grain size and smoother surface topography of the perovskite absorber. In addition, the undercoordinated lead ions in the perovskite layer may be passivated by the carbonyl group in the 5-chloroindolin-2-one unit, thereby reducing the number of nonradiative recombination centers. Meanwhile, the IDT-Cl adjusts the energy level mismatch between the perovskite and two adjacent carrier transport layers, leading to easy charge collection. By the multifunctional effect of the IDT-Cl molecule, the modified device yields a high power conversion efficiency (PCE) of 24.46%, 8.8% higher than that of the control PSC (22.48%). More importantly, the hydrophobic alkyl side-chain of the IDT-Cl molecule further ensures enhanced humidity stability of the perovskite film and environmental, thermal, and light stabilities of the PSC devices. [ABSTRACT FROM AUTHOR]

Fiber-shaped supercapacitors (FSSCs) are promising devices in the wearable electronics because of their good flexibility, weavability, tiny volume and lightweight. However, the low stretchability and energy density limit their practical applications on wearable electronics requiring deformation and high energy density. It remains challenging to increase the energy densities of FSSCs without sacrificing their stretchability. Herein, we design and construct a wearable, stretchable and high-energy density CNT/MnO2 nanosheets FSSCs by wrapping the fiber supercapacitors on the spandex yarn. The CNT/MnO2 FSSCs show high stretchability up to 80%, ultrahigh capacitances of 685 mF cm−2 and energy density of 15.2 μWh cm−2. Furthermore, the CNT/MnO2 FSSCs have the good flexibility, stability and ultralong cycle life. In addition, we also develop the in situ characterization strategy to evaluate the structure evolution during the stretching process of the CNT/MnO2 FSSCs for better understanding the structure evolution of stretchable FSSCs. This work paves the way for the high-performance stretchable energy storage devices. [ABSTRACT FROM AUTHOR]

Hole transport layers (HTLs) play a significant role in the performance of perovskite solar cells. A new class of linear small-molecules based on bis(4-methylthio)phenyl)amine as an end group, carbon, oxygen and sulfur as the center atoms for the center unit (denoted as MT-based small-molecule), respectively, have been applied as HTL, and two of them presented the efficiency over 20% in the planar inverted perovskite solar cells (PSCs), which demonstrated a significant improvement in comparison with the widely used HTL, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (known as PEDOT:PSS), in the planar inverted architecture. The ultrafast carrier dynamics show that the excited hot carrier cooling process of MT-based small-molecule HTL samples is faster than that of PEDOTPSS samples. The kinetic analysis of photo-bleaching peaks of femtosecond transient absorption spectra reveals that the traps at the interface between MT-based small-molecule HTLs and MAPbI3 can be filled much quicker than that at PEDOT/MAPbI3 interfaces. Moreover, the hole injection time from MAPbI3 to MT-based small-molecule HTLs is around 10 times quicker than that to PEDOTPSS. Such quick trap filling and hole extraction bring a significant enhancement in photovoltaic performances. These findings uncover the carrier transport mechanisms and illuminate a promising approach for the design of new HTLs for highly-efficient perovskite solar cells. [ABSTRACT FROM AUTHOR]

Dual-component silane film consisting of 3-aminopropyltriethoxysilane (APS) and bis[3-(triethoxysilyl)propyl]tetrasulfide (BTESPT) has been prepared on the surface of AZ31 Mg alloy and the effect of different molar ratios and hydrolysis times on the corrosion resistance studied systematically. The results show that, compared with single-component silane films, the dual-component silane film exhibited good and long-term corrosion resistance in 3.5 wt.% NaCl solution when the molar ratio of APS to BTESPT was 1:2 and the hydrolysis time was 1 h. This can be ascribed to a high density of Si-O-Mg bonds in the silane film, tightly connected to the Mg alloy surface. Simultaneously, the substantial siloxane network in the silane film increased the length of the penetration paths for corrosive media, thereby improving the corrosion resistance of the Mg alloy. [ABSTRACT FROM AUTHOR]

Electroless nickel–phosphorus films were produced on silicon substrates in alkaline bath solutions, with the addition of thiourea in a concentration range of 1.0–5.0 mg L−1. The influence of thiourea on the chemical composition, morphology and corrosion resistance of the films was studied. The results revealed thiourea had a major influence on plating rate, phosphorus-content and aggregate size. The optimal content of thiourea was 1 mg L−1. Thiourea accelerated the deposition rate at low concentration of 1 mg L−1, but deceased the deposition rate and the phosphorus content at high concentration. The surface of the film without thiourea was smooth and dense. Also, with increasing thiourea content, the surface evolved into coarse nodular morphology with clear intercolonial boundaries. With the addition of 1 mg L−1 thiourea, the film had better corrosion resistance compared to film without thiourea. [ABSTRACT FROM AUTHOR]

The electron transport layer (ETL) plays a crucial role in the rapidly developed perovskite solar cells (PSCs). SnO2 has become one of the most promising alternatives to the TiO2 ETL due to its superior characteristics, such as the wider bandgap and hysteresis-free. However, at this stage, a lot of preparation methods of SnO2 ETL exist in high temperature and long time, those undoubtedly increase the cost and time of preparation. Herein, we report a low-temperature solution-processed SnO2 ETL without high annealing temperature, and a special bromine salt is used to modify SnO2, which leads to a higher transmittance and improved carrier transport ability. Due to the excellent optical and electrical properties, the photoelectric conversion efficiency of the prepared PSC reaches up to 18.8%. Moreover, it can be fabricated using facile solution processing at low temperature, making it particularly attractive for flexible development and low-cost commercialization.ᅟ [ABSTRACT FROM AUTHOR]

For the current flexible actuators, the long-term performance and the reusability usually cannot meet the practical standards, and the bending direction is usually not controllable. To address this issue, a complicated manufacturing process employed to produce a flexible actuator with desirable bending property and durability. Here, we report an easy-to-prepare and low-cost fabrication method for the preparation of PVDF/PEDOT:PSS/CNTs composite film as a multifunctional actuator. This actuator can generate significant bending when exposed to acetone vapors, and the bending direction is adjustable by orienting the carbon nanotubes on the surface. Furthermore, the actuator can produce voltages up to 90 mV via the piezoelectricity of the PVDF. Overall, our approach provides a simple and promising strategy for producing self-powered devices. [ABSTRACT FROM AUTHOR]

The rapid increase in the aging population prompts the development of wearable devices and sophisticated robots. With their ability to collect complex information about their surroundings via e-skins, robots could perform more dynamic and variable tasks such as rescue missions or caring for the elderly. In this paper, we present a new concept of utilizing a very simple, highly flexible and stretchable capacitor sensor array, that can be attached on the surface of a retractable robot hand to realize three functions: determining the location, shape, and pressure of an object. This adaptive sensing system is accomplished using capacitors connected by aligned carbon nanotube (CNT) films constructed on an elastomer dielectric material, which can reduce the requirement on the accuracy of the machine vision system. This study has a very broad application in the manufacture of intelligent software robots. [ABSTRACT FROM AUTHOR]

ZnO nanowire or nanorod arrays have caused great interest owing to their unique properties and versatile applications in short-wavelength lasers, electroluminescent devices, photocatalytic systems, and solar cells, etc. The electrical and optical properties of ZnO nanorod arrays can be altered and controlled through doping. In this paper, BH plasma treatment was employed to improve the electrical properties of ZnO nanorod arrays prepared by hydrothermal synthesis. A clear decrease in the resistivity of ZnO nanorod arrays with BH plasma treatment was observed. Moreover, the measurement results of XPS and Hall measurement show that the BH plasma treatment can be used to achieve n-type doping via B atoms substitution for Zn atoms. [ABSTRACT FROM AUTHOR]

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The mesoscale assembly process is sensitive to additives that can modify the interactions of the crystal nucleus and the developing crystals with solid surfaces and soluble molecules. However, the presence of additives is not a prerequisite for the mesoscale transformation process. In this study, ZnO sheet networks were synthesized on Al foils by a hydrothermal process. Scanning electron microscopy and transmission electron microscopy images confirmed that under ultrasonic vibration, monolithic polycrystalline ZnO sheets transformed into hexagon-like mesocrystalline tubes or rods. The formation mechanism was discussed. [ABSTRACT FROM AUTHOR]

Multilayer films based on graphene oxide (GO) and multiply-alkylated cyclopentanes (MACs) have been fabricated successfully on silicon substrate via both self-assembled and dip-coating technologies. Given the excellent mechanical properties and frictional properties of GO, the resulting multilayer films composed of GO and MACs with excellent lubricating property are expected to possess improved comprehensive tribological performances. In the current paper, the surface morphology and chemical composition of the films were analyzed using water contact angle meter, X-ray photoelectron spectroscope, and atomic force microscope. A ball-on-plate tribometer was used to evaluate the tribological performances of the films. The results showed that the new multilayer films exhibited excellent load-carrying capacity and durability. Therefore, they are hoped to find promising applications in the lubrication of microelectromechanical systems. [ABSTRACT FROM AUTHOR]

0.14 at% Mn-doped 0.95(Na 1/2Bi 1/2)TiO 3-0.05BaTiO 3 (0.95NBT-0.05BT) lead-free single crystals were grown by a top-seeded solution growth method (TSSG). X-ray powder diffraction measurement showed that the as-grown single crystals exhibit rhombohedral perovskite structure with apparent distortion. With the increase of temperature, successive structural phase transitions occur in the Mn-doped 0.95NBT-0.05BT single crystals. After poling, apparent dielectric anomaly is induced accompanied by the increase of the character of diffuse phase transition and the decrease of the value of dielectric constant. The Mn-doped 0.95NBT-0.05BT single crystals exhibit complex domain structure, in which micro and macro domains coexist with statistically 4 mm symmetry. The Mn-doped 0.95NBT-0.05BT lead-free single crystals exhibit excellent piezoelectric and pyroelectric properties, which will lead to promising advance in piezoelectric and pyroelectric applications. The infrared-absorption band occurred around 630.6 cm −1 can be assigned to the “stretching” normal vibration of [Na 1/2Bi 1/2]/Ti-O group. The three diffused Raman bands centered around 300, 560 and 800 cm −1 can be attributed to F2g [TiO 6] bending vibration, A1g [TiO 6] stretching vibration and “soft mode” mixed by bending and stretching vibrations. [ABSTRACT FROM AUTHOR]

A uniform closely packed hexagonal array of porous anodic alumina (PAA) film with an average pore diameter of ~100 nm and a pore height of ~330 nm was obtained by anodizing in oxalic acid solution. Low surface energy molecules of perfluoropolyether (PFPE) and octadecyltrichlorosilane (OTS) were used to enhance the hydrophobicity of the PAA and aluminum (Al) surface. The tribological performances were investigated in detail. The results showed that the static friction coefficient of PAA was much lower than that of smooth Al, which could be due to the higher hardness of the PAA than that of Al. PAA modified with PFPE was characterized by lower friction coefficient and longer wear life as compared with bare Al, PAA, and PAA modified with OTS. This is caused by the combined effects of flexibility, mobility, and inherent lubricity of PFPE molecules and the nanoporous structure of PAA as a reservoir for lubricants and wear particles. [ABSTRACT FROM AUTHOR]

AgS quantum dots were deposited on the surface of TiO nanorod arrays by a two-step photodeposition. The prepared TiO nanorod arrays as well as the AgS deposited electrodes were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, suggesting a large coverage of AgS quantum dots on the ordered TiO nanorod arrays. UV-vis absorption spectra of AgS deposited electrodes show a broad absorption range of the visible light. The quantum dot-sensitized solar cells (QDSSCs) based on these electrodes were fabricated, and the photoelectrochemical properties were examined. A high photocurrent density of 10.25 mA/cm with a conversion efficiency of 0.98% at AM 1.5 solar light of 100 mW/cm was obtained with an optimal photodeposition time. The performance of the QDSSC at different incident light intensities was also investigated. The results display a better performance at a lower incident light level with a conversion efficiency of 1.25% at 47 mW/cm. [ABSTRACT FROM AUTHOR]

High performance is expected in dye-sensitized solar cells (DSSCs) that utilize one-dimensional (1-D) TiO nanostructures owing to the effective electron transport. However, due to the low dye adsorption, mainly because of their smooth surfaces, 1-D TiO DSSCs show relatively lower efficiencies than nanoparticle-based ones. Herein, we demonstrate a very simple approach using thick TiO electrospun nanofiber films as photoanodes to obtain high conversion efficiency. To improve the performance of the DSCCs, anatase-rutile mixed-phase TiO nanofibers are achieved by increasing sintering temperature above 500°C, and very thin ZnO films are deposited by atomic layer deposition (ALD) method as blocking layers. With approximately 40-μm-thick mixed-phase (approximately 15.6 wt.% rutile) TiO nanofiber as photoanode and 15-nm-thick compact ZnO film as a blocking layer in DSSC, the photoelectric conversion efficiency and short-circuit current are measured as 8.01% and 17.3 mA cm, respectively. Intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy measurements reveal that extremely large electron diffusion length is the key point to support the usage of thick TiO nanofibers as photoanodes with very thin ZnO blocking layers to obtain high photocurrents and high conversion efficiencies. [ABSTRACT FROM AUTHOR]

Silicon monoxide/graphite/multi-walled carbon nanotubes (SiO/G/CNTs) material was prepared by ball milling followed by chemical vapor deposition method and characterized by X-ray diffraction, scanning electron microscopy (SEM), galvanostatic charge-discharge, and AC impedance spectroscopy, respectively. The results revealed that SiO/G/CNTs exhibited an initial specific discharge capacity of 790 mAh g with a columbic efficiency of 65%. After 100 cycles, a high reversible capacity of 495 mAh g is still retained. The improved electrochemical properties were due to beneficial SEI by the SEM and EIS results. [ABSTRACT FROM AUTHOR]