High-Performance Supercapacitors Based on ɛ-MnO2/RGO Fiber Electrodes for Wearable Energy Storage.

Hybrid fibers based on MnO2/reduced graphene oxide have been fabricated for flexible energy storage devices. Graphene oxide nanoflakes were reduced in a polytetrafluoroethylene (PTFE) pipeline under the appropriate condition to develop a fiber current collector, which also provides the possibility of weaving. The RGO fiber with the radius of about 35 µm has a resistance of 150 Ω · cm. MnO2 nanoflakes directly grow on the RGO fiber surface acting as the electrode material of the device. The MnO2/RGO hybrid fibers provide excellent energy storage performances. The as-fabricated SC exhibits a high areal capacitance of 1.37 F·cm-2 at the scan rate of 1 mV·s-1, and outstanding long-term cycling stability of 93.75% retention after 5000 cycles. This work demonstrates a cost-effective and versatile strategy for wearable energy storage devices.

Enhanced photo-response properties of a single ZnO microwire photodetector by coupling effect between localized Schottky barriers and piezoelectric potential.

The coupling effect between localized Schottky barriers (SBs) and piezoelectric potential that impact the photo-response properties of a single ZnO microwire (MW) photodetector (PD) is studied. Localized SBs is introduced by Au NPs decoration. The negatively charged Au NPs deplete more carriers near the ZnO surface, which raises the SB height and sharply reduces the recover time of the PD from 142.4 s to 0.7 s. Moreover, after applying the compressive strain, the band structure of ZnO MW changes and piezoelectric potential generates, which further raises the SB height, thickens the depletion region and improves photo-response properties of the detector. The dark current is reduced by about 5 orders and its on/off current ratio increased by about 6 orders, which decreases the power consumption of the detector significantly. Under the above coupling effect between piezoelectric potential and localized SBs, the recover time of the detector is further reduced to 0.1 s ultimately. This work suggests that rational integration of localized SBs and piezoelectric potential is a viable approach to get ZnO MW PDs with high on/off ratio, ultrafast response speed and low power consumption.

First-principles study of phase transition in theα-In2Se3/metal heterostructures.

With the discovery of two-dimensional (2D) ferroelectric materials such as CuInP2S6andα-In2Se3, the ferroelectric field effect transistors (Fe-FETs) based on these materials have entered a rapid-development period. The metal/semiconductor contact is an unavoidable topic in the construction of devices. In this paper, heterostructuresα-In2Se3/metals (Pd, Pt, Cu, Ag and Au) are discussed. According to different stacking types, the structures and energy of 160 heterostructures are calculated and compared. Whenα-In2Se3contacts with the Pd, Pt and Cu, theα-In2Se3may transforms intoß-In2Se3. This phenomenon has hardly been mentioned or analyzed in previous reports. Contacting with the Au and Ag, theα-In2Se3maintains the original structure. The internal physical mechanism of phase transition is explained from the binding energy and the charge transfer. The paper provides sufficient theoretical support for research and development of the Fe-FETs based onα-In2Se3.

Electronic structure characteristics of two-dimensional ferroelectric heterostructuresα-In2Se3/ZnSe.

At present, chips urgently need breakthrough development in the power consumption and integration. The chip integrates billions or even tens of billions of electronic components, such as field effect transistor, diode and so on. Therefore, the research and development of new low-power electronic components with smaller size is an effective method to reduce chip power consumption and improve chip integration. In this paper, the ferroelectric field effect transistor (Fe-FET) based on two-dimensional heterostructuresα-In2Se3/ZnSe is proposed. Based on the first principle, the program will analyze the stability and band structure ofα-In2Se3/ZnSe under different stacking modes. In the heterojunction, the microphysical mechanism of ferroelectric polarization affecting the electronic structure is revealed from the aspects of charge transfer at the interface and the asymmetric surfaces with different work function. Combined with the non-equilibrium Green's function transport theory, the transport properties of Fe-FET based on theirα-In2Se3/ZnSe will be studied. The application will provide sufficient theoretical support for research and development of the device based onα-In2Se3/ZnSe structure.

Low-Temperature UVO-Sintered ZnO/SnO2 as Robust Cathode Buffer Layer for Ternary Organic Solar Cells.

The cathode buffer layer (CBL) plays a crucial role in organic solar cells (OSCs), and it has been challenging to obtain high-quality CBL by using simple and reliable processes. In this paper, the bilayer structure consisting of ZnO nanoparticles (NPs) and sol−gel SnO2 was prepared by the low-temperature (<100 °C) UV-ozone (UVO) sintering process and used as the robust CBL for ternary OSCs based on PTB7-Th:PCDTBT:PC70BM. The results show that the insertion of SnO2 can effectively fill the cracks and pores on the surface of the ZnO NP film, thereby improving the overall compactness and flatness of the CBL and reducing the defect density inside the CBL. Furthermore, the insertion of SnO2 slightly improves the transmittance of the CBL to photons with wavelengths in the range of 400−600 nm, and also increases the electron mobility of the CBL thus facilitating the extraction and transport of the electrons. Compared to the devices using UVO-ZnO and UVO-SnO2 CBLs, the devices with UVO-ZnO/SnO2 CBL exhibit exceptional performance advantages, the best power conversion efficiency (PCE) reaches 10.56%. More importantly, the stability of the devices with ZnO/SnO2 CBL is significantly improved, the device (PCE) still maintains 60% of the initial value after 30 days in air. The positive results show that the UVO-ZnO/SnO2 is an ideal CBL for OSCs, and due to the low-temperature process, it has great application potential in flexible OSCs.

Research on Photoelectric Responses of SnO2 Film to Humidity Under UV Light Irradiation.

In this work, to research the photoelectric responses to humidity using a semiconductor film, an ultraviolet (UV) light induced device has been investigated on SnO2 film at room temperature. Screen printing method was used to prepare SnO2 film on the Al2O3 substrate. The crystalline structure and morphology of SnO2 was characterized with XRD and FE-SEM. The UV light induced photoelectric responses of SnO2 to a constant humidity (20% RH) were evaluated firstly under four different bias voltages. At 2 V bias voltage, the photocurrent amplitude reaches 4.58 µA, which is higher than that of 0.2 V bias (0.27 µA). Then the photoelectric responses to different relative humidity conditions (20% RH, 40% RH and 60% RH) were tested. The results display that the photocurrent decreased while the relative humidity increased. To illustrate the anomaly current of SnO2 film at 60% RH, the darkcurrent to different relative humidity conditions (20% RH, 40% RH and 60% RH) were also tested. To make clear these results, corresponding probable illustration was proposed.

UV Light Activated Multi-Cycle Photoelectric Properties of TiO2 and CdS/TiO 2 Films in Formaldehyde.

In this work, UV light activated multi-cycle photoelectric properties of TiO2 and CdS/TiO2 films in formaldehyde were researched. TiO2 film was prepared by screen printing, CdS/TiO2 compounded film was synthesized by SILAR method. XRD and FE-SEM was used to characterize the TiO2 and CdS/TiO2 samples. Multi-cycle photoelectric properties of TiO2 and CdS/TiO2 with uv light on and off were evaluated by testing the photocurrent. On one hand, under the same bias voltage, CdS/TiO 2showed a higher photocurrent than that by TiO2. The reason for this result should be ascribed to the compounded structure in CdS/TiO2, with which the separation and transfer of photogenerated electron-hole pairs could be improved. On the other hand, with the testing cycle number increased, the photocurrent amplitudes of TiO2 and CdS/TiO2 increased. These results suggested that the time to reach a stable photocurrent value for TiO2 and CdS/TiO2 is much longer than one cycle time (300 S). To illustrate the increased photocurrent amplitude value cycle by cycle, the photocurrent of CdS/TiO2 to a much longer time (more than 4000 seconds) was also tested. To explain these results, corresponding possible illustrations were presented.

Nanoscale Phase Separation in Ternary Organic Solar Cells Based on PTB7:PC70BM:IC70BA.

As a fullerene derivative, IC70BA is widely used in the ternary organic solar cells (TOSCs) to increase the open circuit voltage (Voc) of the devices. Unfortunately, most of the literature shows that IC70BA will lead to a reduction in the short-circuit current density (Jsc) and fill factor (FF). In this work, IC70BA is added to the PTB7:PC70BM binary system to form the ternary system, which is composed of one donor and two fullerene acceptors. Surprisingly, the addition of IC70BA does not immediately lead to a decrease in Jsc and FF. In fact, the appropriate weight ratio of IC70BA in fullerenes can simultaneously increase the Voc, Jsc, and FF of the TOSCs. The synergistic optimization of the surface and bulk morphology of the ternary active layer suppresses the attenuation of Jsc and FF. The smooth surface and suitable phase separation size effectively guarantee the separation, transport and extraction of the charge. Moreover, the addition of IC70BA can significantly improve the hole transport capacity of the active layer, and the optimal hole mobility is 5.13 - 10"4 cm²V-1S-1. Finally, the TOSCs with 10% weight ratio of IC70BA gives the optimal PCE of 9.24% and ideality factor of 2.3.

Aminomethyl-Functionalized Carbon Nanotubes as a Host of Small Sulfur Clusters for High-Performance Lithium-Sulfur Batteries.

Here we propose an effective strategy to stabilize small sulfur species by using aminomethyl-functionalized carbon nanotubes (AM-CNT) without impairing the conductive channel of the carbon nanotube (CNT) cathode. The linear Sn clusters can be anchored strongly to the AM-CNT for the favorable size of n=5 and the maximum size of n=6 in the production of the cathode, which depresses the mass loss of active sulfur effectively and eliminates the formation of high-order polysulfides completely during the discharge process. The most stable 3 D cross-linked Inter-S5 -AM-CNT network shows a fast electron transfer redox reaction through the CNT skeleton that possesses a theoretical capacity of 1337 mA h g-1 (based on sulfur) or 592 mA h g-1 (based on the cathode). The discharge products of the linear S5 cluster tend to form a hyperbranched tight structure through N⋅⋅⋅S⋅⋅⋅Li bridges that are fully impregnated in the AM-CNT bundles, and thus stabilize the entire system. Importantly, this study provides vital guidance into how to design cathodes based on small sulfur clusters for Li-S batteries to depress the shuttle effect intrinsically during charge-discharge cycles, which can be extended to the other small-sulfur-cluster-based batteries.

UV Light Driven Photoelectric Properties of ZnO Film to Humidity.

UV light driven photoelectric properties of ZnO film to humidity were researched. ZnO film was prepared through the method of screen printing sustained on Al2O3 substrate. ZnO was characterized by XRD, FE-SEM and EDX. The time-dependent UV light driven photoelectric properties of ZnO were investigated by exposing it to different bias voltages and different relative humidity (20% RH, 40% RH, 60% RH and 80% RH). On one hand, the photoelectric properties of ZnO increased with the augmenting of bias voltage, which shows that a higher bias causes more separation of carriers. On the other hand, the photocurrent decreased with the increase in relative humidity, which shows that bigger humidity results in smaller photoelectric property. To discuss these results, corresponding possible illustrations for the photoelectric properties under different conditions were proposed.

[Characteristics in Raman spectrum of serum of gastric cancer patients].

OBJECTIVE: To investigate the characters of Raman spectrum in gastric cancer patients through comparing serum of functional dyspepsia patients, serum of gastric cancer patients with SGC7901 cell culture fluid, correlation with culturing time of cell line, and research the recourse of these special Raman peak. METHODS: Peripheral blood samples were collected from 25 gastric cancer patients and 10 functional dyspepsia (FD) patients. Human gastric cancer cells of the line SGC7901 were cultured. The serum samples of the gastric cancer patients and of the FD patients, and the culture fluid of SGC7901 cell underwent Raman spectroscopy with 230 nm and 100 nm as the least peaks respectively. Serum of normal person, lysate, and 1604 culture fluid were used as controls. RESULT: Seven reproducible Raman peaks at the wavelengths of 583, 633, 656, 674, 707, 773 and 799 nm were detected, with 230 nm as the least peak, in the serum samples of gastric cancer patients. Raman peaks at the wavelengths of 633, 656, and 674 nm were detected only in the serum samples of gastric cancer patients, and the Raman peaks at the wavelengths of 533, 707, 773, and 799 nm of the serum of gastric cancer patients (96.5 +/- 6.0, 76.9 +/- 4.7, 63.7 +/- 4.5, 285.7 +/- 18.6) were all remarkably higher than those of the serum samples of FD patients (40.3 +/- 1.8, 27.9 +/- 1.9, 22.9 +/- 1.4, 113.2 +/- 7.7, all P < 0.01). Similar condition, with 100 nm as the least peak, could detected in the Ramon peaks at the above mentioned wavelengths between the serum samples of the gastric cancer patients and the 1640 culture medium. The Raman peak of the cell culture fluid was positively correlated with the time of cell culture. The Raman peaks of the gastric cell lysate at the wavelengths of 583, 633, and 656 nm were significantly different from those of the cell culture fluid (P = 0.027, 0.029, and 0.043 respectively). CONCLUSION: The serum of gastric cancer patients has specific reproducible Raman spectrum. The cell content possibly is part of the reason of the special characters in Raman spectrum of gastric cancer serum.

[Differentiating gastric cancer cell from normal cell by laser Raman spectrum].

The gastric cancer cell and normal cell were comparatively detected by means of laser Raman spectrum in the present paper. The special Raman spectrum wave crest of gastric cancer cell was inquired. It was found that the special Raman spectrum wave crest of gastric cancer cell differs from the one of normal cell. After the sample at concentration of 1.25 x 10(5) individual x mL(-1) was cultivated for several days, a few special Raman spectrum wave crests of sample at 583, 633 and 656 nm respectively were detected. This is a few new special Raman spectrum wave crests rarely reported. Whether at the special Raman spectrum wave crests or at the same several Raman spectrum wave crests 674, 707, 773 and 799 nm for both canner cell and normal cell, the Raman spectrum intensity increases with the cancer cell concentration. As a result, the laser Raman spectrum analyse is considered truly a kind of rapid and effectual method to check cancer cell.

High-Performance Solid-State Supercapacitors Fabricated by Pencil Drawing and Polypyrrole Depositing on Paper Substrate.

A solid-state powerful supercapacitor (SC) is fabricated with a substrate of Xerox paper. Its current collector based on a foldable electronic circuit is developed by simply pencil drawing. Thin graphite sheets on paper provide effective channels for electron transmission with a low resistance of 95 Ω sq-1. The conductive organic material of polypyrrole coated on thin graphite sheets acts as the electrode material of the device. The as-fabricated SC exhibits a high specific capacitance of 52.9 F cm-3 at a scan rate of 1 mV s-1. An energy storage unit fabricated by three full-charged series SCs can drive a commercial light-emitting diode robustly. This work demonstrated a simple, versatile and cost-effective method for paper-based devices.

Hierarchical nanostructures of polypyrrole@MnO2 composite electrodes for high performance solid-state asymmetric supercapacitors.

A solid-state high performance flexible asymmetric supercapacitor (ASC) was fabricated. Its anode is based on organic-inorganic materials, where polypyrrole (PPy) is uniformly wrapped on MnO2 nanoflowers grown on carbon cloth (CC), and its cathode is made of activated carbon (AC) on CC. The ASC has an areal capacitance of 1.41 F cm(-2) and an energy density of 0.63 mW h cm(-2) at a power density of 0.9 mW cm(-2). An energy storage unit fabricated using multiple ASCs can drive a light-emitting diode (LED) segment display, a mini motor and even a toy car after full charging. The high-performance ASCs have significant potential applications in flexible electronics and electrical vehicles.

Series asymmetric supercapacitors based on free-standing inner-connection electrodes for high energy density and high output voltage.

Asymmetric supercapacitors (ASCs) based on free-standing membranes with high energy density and high output voltage are reported. MnO(2) nanowire/carbon nanotube (CNT) composites and MoO(3) nanobelt/CNT composites are selected as the anode and the cathode materials of the devices, respectively. The ASC has a high volumetric capacitance of 50.2 F cm(-3) at a scan rate of 2 mV s(-1) and a high operation voltage window of 2.0 V. Especially, after a middle layer with an inner-connection structure was inserted between the anode and the cathode, the output voltage of the whole device can achieve 4.0 V. The full cell of series ASCs (SASC) with an inner-connection middle layer has a high energy density of 28.6 mW h cm(-3) at a power density of 261.4 mW cm(-3), and exhibits excellent cycling performance of 99.6% capacitance retention over 10,000 cycles. This strategy of designing the hybridized structure for SASCs provides a promising route for next-generation SCs with high energy density and high output voltage.

Ultrathin and lightweight 3D free-standing Ni@NiO nanowire membrane electrode for a supercapacitor with excellent capacitance retention at high rates.

A free-standing binder-free 3D Ni@NiO nanowire membrane is fabricated by a simple filtration method followed by thermal annealing. With an appropriate annealing temperature, the functional nanowires can keep their rough and echinate surface, and the conductive network composed of welded nickel nanowire cores is well-preserved without isolation (0.53 Ω/sq). The unique 3D multigrade mesporous structure not only accelerates the intercalation and deintercalation velocity of electrolyte ions but also provides numerous electroactive sites for the Faraday reaction. As a result, the supercapacitor electrode can preserve a capacitance retention of 96.1% (36.9 F/cm(3)) with a high discharge current density, indicating its wonderful rate capability. The fabricated membrane electrode exhibits high volumetric capacitance, stable cycling life, and remarkable retention of the capacitance at high rate, energy, and power density, making it a promising candidate for application in portable electronic products.

Solid-state high performance flexible supercapacitors based on polypyrrole-MnO2-carbon fiber hybrid structure.

A solid-state flexible supercapacitor (SC) based on organic-inorganic composite structure was fabricated through an "in situ growth for conductive wrapping" and an electrode material of polypyrrole (PPy)-MnO2 nanoflakes-carbon fiber (CF) hybrid structure was obtained. The conductive organic material of PPy greatly improved the electrochemical performance of the device. With a high specific capacitance of 69.3 F cm(-3) at a discharge current density of 0.1 A cm(-3) and an energy density of 6.16 × 10(-3) Wh cm(-3) at a power density of 0.04 W cm(-3), the device can drive a commercial liquid crystal display (LCD) after being charged. The organic-inorganic composite active materials have enormous potential in energy management and the "in situ growth for conductive wrapping" method might be generalized to open up new strategies for designing next-generation energy storage devices.

Cable-type supercapacitors of three-dimensional cotton thread based multi-grade nanostructures for wearable energy storage.

A novel cable-type flexible supercapacitor with excellent performance is fabricated using 3D polypyrrole(PPy)-MnO2 -CNT-cotton thread multi-grade nanostructure-based electrodes. The multiple supercapacitors with a high areal capacitance 1.49 F cm(-2) at a scan rate of 1 mV s(-1) connected in series and in parallel can successfully drive a LED segment display. Such an excellent performance is attributed to the cumulative effect of conducting single-walled carbon nanotubes on cotton thread, active mesoporous flower-like MnO2 nanoplates, and PPy conductive wrapping layer improving the conductivity, and acting as pseudocapacitance material simultaneously.