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An electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT)/screen-printed reduced graphene oxide (rGO)–chitosan (CS) bilayer material was coated on carbon cloth to form electrodes for gel-electrolyte flexible supercapacitors. The conductive polymer and carbon-based materials mainly contribute pseudocapacitance (PC) and electrical double-layer capacitance (EDLC), respectively. The high porosity and hydrophilicity of the PEDOT/rGO–CS bilayer material offers a large contact area and improves the contact quality for the gel electrolyte, thereby enhancing the capacitive performance. Cyclic voltammetry (CV) under a potential scan rate of 2 mV/s revealed that a maximum areal capacitance of 1073.67 mF/cm2 was achieved. The capacitance contribution ratio PC/EDLC was evaluated to be ∼67/33 by the Trasatti method. A 10,000-cycle CV test showed a capacitance retention rate of 99.3% under a potential scan rate of 200 mV/s, indicating good stability. The areal capacitance remains similar under bending with a bending curvature of up to 1.5 cm–1.

Wearable bio-sensing devices are considered promising for ubiquitous heath monitoring. To accurately read out small bio-signals, the development of high-performance flexible front-end circuits is crucial. Oxide semiconductors are considered one of the most promising active channel materials for on-polymeric-foil electronics. In this article, a high-gain flexible complementary metal–oxide–semiconductor (CMOS) inverter with a beta ratio of 1, a desirable feature for device miniaturization, was demonstrated by monolithically integrating a top-gated n-type indium gallium zinc oxide (IGZO) thin-film transistor (TFT) and a bottom-gated p-type SnO TFT on a 5.5- $\mu \text{m}$ -thick polyimide substrate. The influence of atomic layer deposited (ALD)-HfO2 capping layer on the properties of oxide active channels has been analyzed. The flexible inverter exhibited a high static voltage gain of 370 V/V and balanced noise margins (noise margin high of 4.8 V, noise margin low of 4.7 V) for a supply voltage of 10 V. In addition, the voltage transfer characteristics remained virtually unchanged when the device was subjected to an outward or an inward bending radius of 2.5 mm, indicating the complementary oxide-TFT-based inverter is practical for flexible electronics applications.

LiCl + Mn(NO3)2·4H2O pastes are screen-printed on a carbon cloth substrate and then calcined at 400 °C for 6 h in a tube furnace to convert them into LiMn2O4. Ar, Ar+5%H2, or Ar+5%O2 low-pressure plasma is then used to treat the LiMn2O4/carbon cloth. The treated LiMn2O4/carbon cloth is then used as the electrode for a Li-ion hybrid supercapacitors (Li-HSCs) with a three-electrode configuration in 1-M Li2SO4 liquid electrolyte. Ag/AgCl and Pt electrodes were used as reference and counter electrodes, respectively. Li-HSCs are characterized by galvanostatic charging/discharging, cyclic voltammetry, and electrochemical impedance spectroscopy. The results indicate that plasma treatment improves the Li-HSCs performance. In particular, Ar+5%O2 plasma treatment increases the areal capacity by ∼24% to 23.12 μA h cm−2. It also improves the coulomb efficiency and capacity retention rate of LiMn2O4 Li-HSCs.

This study investigates the effect of low-pressure plasma (LPP) processing of a graphite foil as the cathode of a paper-based fluidic Al-air battery. A 10-s plasma treated battery exhibited better discharge performance in terms of the current density, power density, and energy density compared with an untreated battery. Scanning electron microscopy, x-ray photoelectron spectroscopy, and water contact angle measurements were used to investigate the difference in the surface properties of the graphite foil before and after LPP modification. Further, linear sweep voltammetry, constant current discharge measurement, and electrochemical impedance spectroscopy analysis were used to demonstrate the enhancement in discharge performance.

A scan-mode low-temperature (

This study fabricated temperature sensors with a mixture of carbon nanotube (CNT) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). CNT/PEDOT:PSS solutions with three different ratios—1/5, 1/9, and 1/13—prepared and aged for 0, 3, and 6 days. The temperature sensor was fabricated by drop-casting the aged solution onto a flexible polydimethylsiloxane (PDMS) substrate. As the aging time of CNT/PEDOT:PSS solutions with ratios of 1/5, 1/9, and 1/13 increased to 6 days, the temperature coefficient of resistance (TCR) of CNT/PEDOT:PSS decreased from −1.97, −1.99, and −2.15 (%/°C) to −2.80, −2.61, and −2.51 (%/°C) (i.e. temperature sensitivity increased) and temperature index (TI) also increased from 2242.5, 2249.1, and 2503.8 (K) to 3530.1, 3085.7, and 3002.5 (K), respectively. As the aging time of CNT/PEDOT:PSS solution increased to 6 days, its Seebeck coefficient increased from 52.4 to 114.5 μV K−1. These results show that the aging of CNT/PEDOT:PSS solution significantly increased the temperature sensitivity and Seebeck coefficient via the dedoping of PEDOT:PSS. This serves as a facile method to improve the temperature sensitivity of the CNT/PEDOT:PSS composite.

Reduced graphene oxide (rGO)-polyaniline (PANI) supercapacitors (SCs) are tested with 1 M LiCl, Li2SO4, and H2SO4 electrolytes. The SC performance is evaluated by electrical impedance spectroscopy, cyclic voltammetry (CV), and galvanostatic charging/discharging measurements. Electrochemical experiments indicate that rGO-PANI SCs with lithium salt electrolytes show a large pseudocapacitance (PC) effect whereas that with H2SO4 electrolyte shows a large electrical double-layer capacitance (EDLC) effect. The rGO-PANI SC with H2SO4 electrolyte has the largest areal capacitance of 48.83 mF/cm2, whereas those with LiCl and Li2SO4 electrolytes have the areal capacitances of 31.69 mF/cm2 and 22.35 mF/cm2, respectively. After a 10,000-cycle CV stability test, the rGO-PANI SC with Li2SO4 electrolyte shows some ion embedding, resulting in better cycling stability than those of SCs with LiCl and H2SO4 electrolytes.

A nitrogen DC-pulse atmospheric-pressure plasma jet (APPJ) is used to convert spin-coated nickel acetate liquid precursor films into continuous and dense NiO compound thin films. Films calcined by APPJ for 0–120 s are characterized. X-ray photoelectron spectroscopy (XPS) indicates that metallic Ni content increases and then decreases as the APPJ calcination time increases. Wrinkles are formed on films with higher metallic Ni contents owing to the compressive stresses caused by the mismatch between the film and the substrate. Plasma reactive species contain electrons and ions that could cause oxidation and reduction reactions simultaneously. This leads to the complex compositions in the resultant films. The film becomes more metal-like when the metallic Ni content is high and becomes more semiconductor-like for low metallic Ni content film. Seebeck measurements confirms that all APPJ-converted NiO compound films are of p-type and could potentially be used as the hole transport layer or the hole injection layer of optoelectronic devices.

This article investigates the effect of mechanical bending strain on the electrical performance and gate-bias stability of flexible p-type tin monoxide (SnO) thin-film transistors (TFTs). The on-polyimide SnO TFTs have an inverted-staggered structure with a back channel passivated by SiN x and HfO2 layers. The as-fabricated linear field-effect mobility, threshold voltage, subthreshold swing, and ON/OFF current ratio are 0.41 cm $^{{2}}\text{V}^{-{1}}\text{s}^{-{1}}$ , 0.74 V, 1.9 V/dec, and $1.1\times 10^{{4}}$ , respectively. The field-effect mobility decreases as the applied tensile strain increases, while it stays almost unaltered when a compressive strain is applied. A prominent increase of the positive-gate-bias-stress-induced threshold voltage shift is observed when the TFT is outwardly bent. The result shows that the mechanical tensile strain has a more significant impact on the electrical performance of p-type SnO TFTs.

We compare screen-printed flexible reduced graphene oxide(rGO)-chitosan(CS) supercapacitors (SCs) prepared using poly(3, 4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) pastes and carbon pastes (CPs). SCs with PEDOT:PSS (PEDOT:PSS/rGO-CS SCs) exhibit a higher pseudocapacitance (PC) than do those with CP. Plasma treatment damages the electrodes and lowers the specific capacitance of SCs. In a galvanostatic charge-discharge (GCD) test with a constant current of 0.25 mA, PEDOT:PSS/rGO-CS and CP/rGO-CS SCs respectively show a maximum specific capacitance of 14.70 mF cm−2 and 4.63 mF cm−2. PEDOT:PSS/rGO-CS and CP/rGO-CS SCs both show excellent performance in the stability and bending tests. With a 5,000-cycle cyclic voltammetry (CV) test, the capacitive retention rates are more than 97%. No degradation is observed for both PEDOT:PSS/rGO-CS and CP/rGO-CS SCs bent with a bending radius of 0.5 cm.

Reduced graphene oxide (rGO) and/or polypyrrole (PPy) are mixed with chitosan (CS) binder materials for screen-printing supercapacitors (SCs) on arc atmospheric-pressure plasma jet (APPJ)-treated carbon cloth. The performance of gel-electrolyte rGO/CS, PPy/CS, and rGO/PPy/CS SCs processed by a dielectric barrier discharge plasma jet (DBDjet) was assessed and compared. DBDjet processing improved the hydrophilicity of these three nanocomposite electrode materials. Electrochemical measurements including electrical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charging-discharging (GCD) were used to evaluate the performance of the three types of SCs. The Trasatti method was used to evaluate the electric-double layer capacitance (EDLC) and pseudocapacitance (PC) of the capacitance. The energy and power density of the three types of SCs were illustrated and compared using Ragone plots. Our experiments verify that, with the same weight of active materials, the combined use of rGO and PPy in SCs can significantly increase the capacitance and improve the operation stability.

A low-temperature (

The effect of atmospheric-pressure dielectric barrier discharge (DBD) treatment on the properties of methylammonium lead iodide (CH3NH3PbI3, MAPbI3) perovskite thin films is investigated. The in-situ DBD-treated MAPbI3 perovskite thin films are then used as the absorber layers for planar n-i-p perovskite solar cells (PSCs). N-O emission system is observed in the plasma during the treatment, indicating the reactions of reactive nitrogen plasma species with the organics in the precursor films. Long DBD treatment duration (60 s) leads to the phase precipitation of PbI2 and degrades the cell efficiency, whereas short DBD treatment duration (20 s) significantly improves the PSC efficiency by nearly 40%. Only slight performance enhancement is observed in the PSCs prepared by conventional thermal treatment at the same substrate temperatures as that for DBD treatment, implying that DBD provides the synergetic effect of the reactivity and plasma heating. Electrochemical impedance spectroscopy (EIS) indicates that the charge recombination impedance increases and then decreases with DBD treatment duration. The shunt resistance also shows a similar trend, and it is consistent with the PSC performance. The PSC with the 20 s DBD-treated absorber layer shows energy conversion efficiency of 14.29%, open circuit voltage of 1.022 V, short circuit current density of 19.45 mA/cm2, and fill factor of 0.72, whereas the corresponding values for the untreated counterpart are 10.32%, 0.976 V, 18.52 mA/cm2, and 0.57. The result shows that short-duration low-temperature DBD treatment effectively enhances the performance of solution-processed PSCs.

A facile surface treatment of the CH3NH3PbI3 film is conducted using a portable dielectric barrier discharge device inside a nitrogen-filled glove box. DBD treatment can promote the surface crystallization of the CH3NH3PbI3 film, increase the conductivity of CH3NH3PbI3 film, and manifest efficient defect passivation. In addition, DBD treatment can remove surface N-containing fragments of perovskite film to produce a lead-rich surface, which not only affords self-passivation effect but also increases the interactions at the perovskite/fullerene interface. Benefitting from the reduced defect density at the perovskite interface, the DBD-treated perovskite film can enable a ∼12.5% enhancement in power conversion efficiency of the derived doped PC61BM-based perovskite solar cells. Such enhancement is mainly contributed from the improvement of open circuit voltage (from 0.885 to 0.922 V) and fill factor (0.698 to 0.759). Detailed optimization of the DBD treatment is carefully investigated in this study.

We use a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/carbon nanotube (CNT) composite as the temperature sensing layer, and the device exhibited a high sensitivity of −2.46%/°C. A sandpaper-molded PDMS with fluorinated surface modification protection layer is used as the superhydrophobic, oleophobic, self-cleaning protective encapsulation layer. This device exhibits a self-cleaning function when it makes contact with liquids such as water, tea, coffee, and milk. In addition, the surface can also repel liquids with low surface tension (such as oil), exhibiting good oleophobicity. Resistance to ultrasonication in an organic solvent for 120 min and a 400-cycle tape peel test reveal durability of this device. The device functions under similar conditions after 1000 bending cycles with a bending radius of 0.875 mm. In this work, we demonstrate a simple and low-cost technique to fabricate durable and wearable temperature sensing devices.

Two-dimensional perovskite solar cells (2-D PSCs) have attracted much research attention in recent years because they are more stable in a regular environment than three-dimensional (3-D) ones are. In this study, we doped Cs into 2D perovskite (BA2(MA)2Pb3I10) films as the absorbing layers of the 2-D p-i-n inverted PSCs to investigate the influence of the Cs doping concentration on the properties of the 2-D perovskite films and the fabricated solar cells. Cs doping clearly improves the power conversion efficiency (PCE) and air stability of the PSCs. Doping perovskite with 10% Cs (the best doping concentration in this study) can increase the PSC efficiency from 7.98% to 10.11%. Scanning electron microscopy indicates the improved surface quality and crystallinity by Cs doping. However, excess Cs doping degrades the PCE of the PSCs. Furthermore, 10% Cs doped PSCs show air stability superior to that of undoped ones in unpackaged humidity environments. After exposure to 55% relative humidity (RH) in 19 °C air for 300 h, the PCE of the PSC decreased by only 39%, in contrast to 84% for the undoped PSC.

In this paper, flexible coplanar top-gate p-type SnO TFTs are demonstrated. The TFT performance was optimized by adjusting the post-deposition annealing temperature of the SnO channel. The on/off current ratio of the TFT first improves and then degrades as the channel annealing temperature increases. With an optimized annealing temperature of 175C, the flexible SnO TFT exhibits a field-effect mobility of 0.71 cm2/V-s, threshold voltage of 5.2 V, subthreshold swing of 1.6 V/decade, and on/off current ratio of 1.6 x 103. The gate-bias stress stability of the optimized TFT was then investigated. When the TFT is at flat state, the threshold voltage shifts after bias-stressed at +10 V and -10 V for 10000 s are 0.2 V and nearly 0 V, respectively. The electrical stability degrades slightly when the TFT is subjected to both mechanical tensile and compressive strains. At a compressive strain of 0.25%, the threshold voltage shifts increase to 0.8 V and -0.3 V for positive and negative bias stress, respectively. At a tensile strain of 0.25%, the corresponding values are 0.7 V and -0.2 V. Compared with unpassivated bottom-gate SnO TFTs, the gate-bias stress stability is greatly improved.

The enzymatic hydrolysis of fish proteins is the principle method for converting under-utilized fish into valuable products for the pharmaceutical and health food industries. In this study, three commercial enzymes (alcalase, bromelain, and papain) were tested for their ability to create eel protein hydrolysates (EPHs) from whole eel (Anguilla marmorata). Freeze-dried EPHs had almost more than 80% solubility (p &lt, 0.05) in solutions ranging from pH 2&ndash, 10. The amino acid profiles of the EPHs showed a high percentage of essential amino acids, including histidine, threonine, valine, isoleucine, and leucine. The emulsion activity index (EAI) of EPH resulted as follows: alcalase group (36.8 &plusmn, 2.00) &gt, bromelain group (21.3 &plusmn, 1.30) &gt, papain group (16.2 &plusmn, 1.22), and the emulsion stability index (ESI) of EPH was: alcalase group (4.00 &plusmn, 0.34) &gt, bromelain group (2.62 &plusmn, 0.44) &gt, papain group (1.44 &plusmn, 0.09). As such, EPH has a high nutritional value and could be used as a supplement to diets lacking protein. EPH showed excellent solubility and processed interfacial properties, which are governed by its concentration. Among of them the alcalase group had the best antioxidant effect at 1,1-diphenyl-2-pyridinohydrazinyl (DPPH) radical method, determination of reducing power and ABTS test compared with other groups. EPH may be useful in developing commercial products like herbal eel extracts that are beneficial to human health.

This study compares supercapacitors with reduced graphene oxide (rGO)‑carbon black (CB) and CB nanocomposite coated carbon cloth electrodes. We use a nitrogen DC-pulse atmospheric pressure plasma jet (APPJ) to process the electrodes. The APPJ processing time is

Nitrogen dc-pulse atmospheric pressure plasma jet (APPJ) is used to fabricate Pt/ZnO composites as the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). Due to the synergetic effect of the reactive plasma species and heat in nitrogen APPJ, the spin-coated precursors including chloroplatinic acid and zinc acetate can be reduced on fluorine-doped tin oxide (FTO) glass substrates in a few seconds. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) analyses indicate that the precursors are reduced to Pt/ZnO under APPJ calcination. Electrochemical impedance spectroscopy (EIS) and Tafel measurement show the promising catalytic activities of Pt/ZnO CEs with low charge transfer resistance and high exchange current density. The efficiency of a DSSC with a 30-s APPJ-calcined Pt/ZnO CE is similar to that with a conventional furnace-annealed Pt CE for 15 min. The results indicate that nitrogen dc-pulse APPJ treatment is an efficient tool for rapidly fabricating Pt/ZnO composite CEs of DSSCs.

This study evaluates carbon cloth treated using dc-pulse nitrogen atmospheric pressure plasma jet (APPJ) for a polyvinyl alcohol (PVA)/sulfuric acid (H2SO4) gel-electrolyte supercapacitor with a polyaniline (PANI)/reduced graphene oxide (rGO) nanocomposite electrode materials. The water contact angle of the carbon cloth decreases from 144.71° to 0° after the scanning APPJ surface treatment. The improved wettability can facilitate the penetration of the electrolyte into the porous electrodes, thereby improving the capacitance. X-ray photoelectron spectroscopy (XPS) indicates the introduction of nitrogen doping into to the carbon fibers of carbon cloth through the nitrogen APPJ treatment. Without APPJ treatment of carbon cloth, the specific (areal) capacitance of the fabricated supercapacitor is 315.0 F g−1 (55.67 mF/cm2); it increases to 580.2 F g−1 (106.89 mF/cm2) with APPJ surface treatment of carbon cloth before screen-printing the PANI/rGO nanocomposite. Electrochemical impedance spectroscopy (EIS) indicates a decreasing charge-transfer impedance at the electrode/electrolyte interface for supercapacitors with APPJ treatment of carbon cloth. This also improves the supercapacitive performance. After 1000-cycle cyclic voltammetry stability test, the capacitance retention rate is ∼85%. Our experimental results suggest that nitrogen dc-pulse APPJ in scanning mode is an efficient tool for enhancing the supercapacitance performance of a PANI/rGO supercapacitor.

This study evaluates DC-pulse nitrogen atmospheric-pressure-plasma-jet processed carbon nanotube (CNT)–reduced graphene oxide (rGO) nanocomposites for gel-electrolyte supercapacitor applications. X-ray photoelectron spectroscopy (XPS) indicates decreased oxygen content (mainly, C–O bonding content) after nitrogen APPJ processing owing to the oxidation and vaporization of ethyl cellulose. Nitrogen APPJ processing introduces nitrogen doping and improves the hydrophilicity of the CNT–rGO nanocomposites. Raman analysis indicates that nitrogen APPJ processing introduces defects and/or surface functional groups on the nanocomposites. The processed CNT–rGO nanocomposites on carbon cloth are applied to the electrodes of H2SO4–polyvinyl alcohol (PVA) gel-electrolyte supercapacitors. The best achieved specific (areal) capacitance is 93.1 F g−1 (9.1 mF cm−2) with 15 s APPJ-processed CNT–rGO nanocomposite electrodes, as evaluated by cyclic voltammetry under a potential scan rate of 2 mV s−1. The addition of rGOs in CNTs in the nanoporous electrodes improves the supercapacitor performance.