Showing papers by "Guozhen Shen published in 2013"

Flexible Asymmetric Supercapacitors Based upon Co9S8 Nanorod//Co3O4@RuO2 Nanosheet Arrays on Carbon Cloth

Abstract: We have successfully fabricated flexible asymmetric supercapacitors (ASCs) based on acicular Co9S8 nanorod arrays as positive materials and Co3O4@RuO2 nanosheet arrays as negative materials on woven carbon fabrics. Co9S8 nanorod arrays were synthesized by a hydrothermal sulfuration treatment of acicular Co3O4 nanorod arrays, while the RuO2 was directly deposited on the Co3O4 nanorod arrays. Carbon cloth was selected as both the substrate and the current collector for its good conductivity, high flexibility, good physical strength, and lightweight architecture. Both aqueous KOH solutions and polyvinyl alcohol (PVA)/KOH were employed as electrolyte for electrochemical measurements. The as-fabricated ASCs can be cycled reversibly in the range of 0–1.6 V and exhibit superior electrochemical performance with an energy density of 1.21 mWh/cm3 at a power density of 13.29 W/cm3 in aqueous electrolyte and an energy density of 1.44 mWh/cm3 at the power density of 0.89 W/cm3 in solid-state electrolyte, which are alm...

New energy storage option: toward ZnCo2O4 nanorods/nickel foam architectures for high-performance supercapacitors.

Abstract: Hierarchical ZnCo2O4/nickel foam architectures were first fabricated from a simple scalable solution approach, exhibiting outstanding electrochemical performance in supercapacitors with high specific capacitance (∼1400 F g–1 at 1 A g–1), excellent rate capability (72.5% capacity retention at 20 A g–1), and good cycling stability (only 3% loss after 1000 cycles at 6 A g–1). All-solid-state supercapacitors were also fabricated by assembling two pieces of the ZnCo2O4-based electrodes, showing superior performance in terms of high specific capacitance and long cycling stability. Our work confirms that the as-prepared architectures can not only be applied in high energy density fields, but also be used in high power density applications, such as electric vehicles, flexible electronics, and energy storage devices.

NiCo2O4 nanowire arrays supported on Ni foam for high-performance flexible all-solid-state supercapacitors

Abstract: Portable electronic devices which are ultrathin, lightweight and even able to roll-up have attracted much attention. Herein, we report the design of flexible all-solid-state symmetric supercapacitors by using two NiCo2O4 nanowire arrays supported on Ni foams as the electrodes. The as-fabricated symmetric supercapacitors have excellent electrochemical performance with a high cell areal capacitance of 161 mF cm−2 at 1 mA cm−2. Good electrochemical performance stability over 3000 cycles was obtained even when the device was under harsh mechanical conditions including both twisted and bent states. As-fabricated all-solid-state supercapacitors could be charged and power a commercial light-emitting-diode, demonstrating their feasibility as an efficient energy storage component and self-powered micro/nano-system. In addition, we were able to grow NiCo2O4 nanowire arrays on many kinds of flexible substrates, including nickel foam, carbon cloth, Ti foil and polytetrafluoroethylene tape. Our work here opens up opportunities for the device configuration for energy-storage devices in the future wearable electronic area and many other flexible, lightweight and high performance functional nanoscale devices.

Three-dimensional hierarchical GeSe2 nanostructures for high performance flexible all-solid-state supercapacitors.

Abstract: Highly flexible stacked and in-plane all-solid-state supercapacitors are fabricated on 3D hierarchical GeSe2 nanostructures with high performance, and, when configured as a self-powered photodetector nanosystem, can be used to power CdSe nanowire photodetectors.

Rechargeable Mg-Ion Batteries Based on WSe2 Nanowire Cathodes

Abstract: The increasing interest in future energy storage technologies has generated the urgent need for alternative rechargeable magnesium ion batteries due to their innate merits in terms of raw abundance, theoretical capacity, and operational safety. Herein, we report an alternative pathway to a new energy storage regime: toward advanced rechargeable magnesium-ion batteries based on WSe2 nanowire-assembled film cathodes. The as-grown electrodes delivered efficient Mg2+ intercalation/insertion activity, excellent cycling life, enhanced specific capacity, and excellent rate capability. We also evaluated the influence of Mg-intercalation behavior on Mg-ion batteries based on WSe2 film cathodes via the first-principles DFT computations. The results reveal the feasibility of using advanced magnesium-ion batteries based on WSe2 film as energy storage components in next-generation optoelectronic systems.

High‐Performance Organic‐Inorganic Hybrid Photodetectors Based on P3HT:CdSe Nanowire Heterojunctions on Rigid and Flexible Substrates

Abstract: Organic-inorganic hybrid photoelectric devices draw considerable attention because of their unique features by combining the relatively low ionization potential of the organic molecules and the high electron affi nity of inorganic semiconductors. Hybrid organic-inorganic poly(3-hexylthiophene) (P3HT):CdSe nanowire heterojunction photodetectors are fi rst demonstrated on silicon substrates, exhibiting a greatly enhanced photocurrent, a fast response, and a recovery time shorter than 0.1 s. Flexible hybrid photodetectors with excellent mechanical fl exibility and stability are also fabricated on both poly(ethylene terephthalate) (PET) substrates and printing paper. The fl exible devices are successfully operated under bending up to almost 180 ° and show an extremely high on/off switching ratio (larger than 500), a fast time response (about 10 ms), and excellent wavelength-dependence, which are very desirable properties for its practical application in high-frequency or high-speed fl exible electronic devices.

High-performance energy-storage devices based on WO3 nanowire arrays/carbon cloth integrated electrodes

Abstract: Ordered WO3 nanowire arrays on carbon cloth (WNCC) conductive substrates are successfully prepared by a facile hydrothermal method. The as-prepared samples were characterized by XRD, SEM and TEM and directly functionalized as supercapacitor (SC) and lithium-ion battery (LIB) electrodes without using any ancillary materials such as carbon black or binder. The unique structural features endow them with excellent electrochemical performance. The SCs demonstrate high specific capacitance of 521 F g−1 at 1 A g−1 and 5.21 F cm−2 at 10 A cm−2 and excellent cyclic performance with nearly 100% capacity retention after 2000 cycles at a current density of 3 A g−1. All-solid-state SCs based on the integrated electrodes are also presented, exhibiting high flexibility without obvious performance declination at different bending states. A high capacity of 662 mA h g−1 after 140 cycles at a 0.28 C rate and excellent rate capabilities are also obtained for LIBs due to the unique structures of the integrated electrodes.

TiO2 modified FeS Nanostructures with Enhanced Electrochemical Performance for Lithium-Ion Batteries

Abstract: Anatase TiO2 modified FeS nanowires assembled by numerous nanosheets were synthesized by using a typical hydrothermal method. The carbon-free nanocoated composite electrodes exhibit improved reversible capacity of 510 mAh g(-1) after 100 discharge/charge cycles at 200 mA g(-1), much higher than that of the pristine FeS nanostructures, and long-term cycling stability with little performance degradation even after 500 discharge/charge cycles at current density of 400 mA g(-1). Full batteries fabricated using the FeS@TiO2 nanostructures anode and the LiMn2O4 nanowires cathode with excellent stability, and good rate capacities could also be achieved. The enhanced electrochemical performance of the composite electrodes can be attributed to the improved conductively of the integrated electrodes and the enhanced kinetics of lithium insertion/extraction at the electrode/electrolyte interface because of the incorporation of anatase TiO2 phase.

Hierarchical silicon nanowires-carbon textiles matrix as a binder-free anode for high-performance advanced lithium-ion batteries

Abstract: Hierarchical silicon nanowires-carbon textiles matrix as a binder-free anode for high-performance advanced lithium-ion batteries

Flexible, planar-integrated, all-solid-state fiber supercapacitors with an enhanced distributed-capacitance effect.

Abstract: Flexible and highly efficient energy storage units act as one of the key components in portable electronics. In this work, by planar-integrated assembly of hierarchical ZnCo₂O₄ nanowire arrays/carbon fibers electrodes, a new class of flexible all-solid-state planar-integrated fiber supercapacitors are designed and produced via a low-cost and facile method. The as-fabricated flexible devices exhibit high-efficiency, enhanced capacity, long cycle life, and excellent electrical stability. An enhanced distributed-capacitance effect is experimentally observed for the device. This strategy enables highly flexible new structured supercapacitors with maximum functionality and minimized size, thus making it possible to be readily applied in flexible/portable photoelectronic devices.

High-detectivity InAs nanowire photodetectors with spectral response from ultraviolet to near-infrared

Abstract: InAs is a direct, narrow band gap (0.354 eV) material with ultrahigh electron mobility, and is potentially a good optoelectronic device candidate in the wide UV-visible-near-infrared region. In this work we report the fabrication of InAs nanowire-based photodetectors, which showed a very high photoresponse over a broad spectral range from 300 to 1,100 nm. The responsivity, external quantum efficiency and detectivity of the device were respectively measured to be 4.4 × 103 AW−1, 1.03 × 106%, and 2.6 × 1011 Jones to visible incident light. Time dependent measurements at different wavelengths and under different light intensities also demonstrated the fast, reversible, and stable photoresponse of our device. Theoretical calculations of the optical absorption and the electric field component distribution were also performed to elucidate the mechanism of the enhanced photoresponse. Our results demonstrate that the single-crystalline InAs NWs are very promising candidates for the design of high sensitivity and high stability nanoscale photodetectors with a broad band photoresponse. Open image in new window

Advanced rechargeable lithium-ion batteries based on bendable ZnCo2O4-urchins-on-carbon-fibers electrodes

Abstract: A novel class of ZnCo2O4-urchins-on-carbon-fibers matrix has been designed, characterized, and used to fabricate high-performance energy storage devices. We obtained a reversible lithium storage capacity of 1180 mA·h/g even after 100 cycles, demonstrating the highreversible capacity and excellent cycle life of the as-prepared samples. Tested as fast-charging batteries, these electrodes exhibited a considerable capacity of 750 mA·h/g at an exceptionally high rate of 20 C (18 A/g), with an excellent cycle life (as long as 100 cycles), which are the best high-rate results reported at such a high charge/discharge current density for ZnCo2O4-based anode materials in lithium rechargeable batteries. Such attractive properties may be attributed to the unique structure of the binder-free ZnCo2O4-urchins-on-carbon-fibers matrix. Full batteries were also developed by combining the ZnCo2O4 anodes with commercial LiCoO2 cathodes, which showed flexible/wearable and stable features for use as very promising future energy storage units. Open image in new window

ZnS Nanostructures: Synthesis, Properties, and Applications

Abstract: Zinc sulfide (ZnS) nanostructures have attracted increasing attention due to their potential application in both conditional optical devices and new generation of nano-electronics and nano-optoelectronics because of their special structure-related chemical and physical properties. In this article, beginning with the synthesis of ZnS nanostructures with various original morphologies, we summarize the state-of-art research progresses on ZnS nanostructures. This is followed by the recent progresses on the improvement of their properties, especially the novel potentialapplications.Wehighlighttherecentachievementsonphotoluminescence,photocatalysis, light-emitting diodes (LEDs), field-effect transistors (FET), sensors, dye-sensitized solar cells, and field emission (FE) based on ZnS nanostructures. Finally, we present an outlook on the future development of ZnS nanostructures.

Fabrication of curled conducting polymer microfibrous arrays via a novel electrospinning method for stretchable strain sensors

Abstract: Stretchable strain sensors based on aligned microfibrous arrays of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)-poly(vinyl pyrrolidone) (PEDOT:PSS-PVP) with curled architectures have been fabricated by a novel reciprocating-type electrospinning setup with a spinneret in straightforward simple harmonic motion. The incorporation of PEDOT:PSS into PVP is confirmed by Raman spectra, which improves the room-temperature conductivity of the composite fibers (1.6 × 10(-5) S cm(-1)). Owing to the curled architectures of the as-spun fibrous polymer arrays, the sensors can be stretched reversibly with a linear elastic response to strain up to 4%, which is three times higher than that from electrospun nonwoven mats. In addition, the stretchable strain sensor with a high repeatability and durability has a gauge factor of about 360. These results may be helpful for the fabrication of stretchable devices which have potential applications in some fields such as soft robotics, elastic semiconductors, and elastic solar cells.

SnO2-microtube-assembled cloth for fully flexible self-powered photodetector nanosystems

Abstract: Integrating an energy conversion or storage device with photodetectors into a self-powered system provides a promising route to future devices aimed at reduced size, low weight and high flexibility. We reported here the fabrication of a fully flexible self-powered photodetector nanosystem by integrating a flexible SnO2-cloth-based ultraviolet photodetector with a flexible SnO2-cloth-based lithium-ion battery. The flexible SnO2-cloth-based ultraviolet photodetectors showed fast response to ultraviolet light with excellent flexibility and stability. Using SnO2-on-carbon-cloth as the binder-free anode and commercial LiCoO2/Al foil as the cathode, a flexible full lithium-ion battery was assembled, exhibiting a reversible capacity of 550 mA h g−1 even after 60 cycles at a current density of 200 mA g−1 in a potential window of 2–3.8 V. When integrated with and driven by the flexible full battery, the fully flexible self-powered photodetector nanosystem exhibits comparable performance with an analogous externally powered device. Such an integrated nanosystem could serve as a wireless detecting system in large areas, as required in applications such as environmental sensing and biosensing.

Facile synthesis and electrochemical properties of CoMn2O4 anodes for high capacity lithium-ion batteries

Abstract: Manganese-based oxides have been proven to be promising materials for applications in high voltage and high energy density Li-ion batteries. In this work, by using hydrothermally synthesized β-MnO2 nanorods as the templates, we prepared single-crystalline CoMn2O4 nano/submicrorods with diameters of about 100 nm and lengths up to tens of micrometers. The electrochemical tests showed that the CoMn2O4 products have a reversible capacity of 512 mA h g−1 at a current density of 200 mA g−1 with a coulombic efficiency of 98% after 100 cycles. A specific capacity of about 400 mA h g−1 was obtained even at a current density as high as 1000 mA g−1, exhibiting a high reversibility and a good capacity retention. This study suggests that CoMn2O4 nano/submicrorods are promising anode materials for high performance lithium-ion batteries.

Performance enhancement of thin-film amorphous silicon solar cells with low cost nanodent plasmonic substrates

Abstract: Performance of thin film photovoltaics largely relies on photon absorption capability. Here, we introduce a novel substrate with patterned aluminum nanodent arrays with unique light management capability. Hydrogenated amorphous silicon thin film solar cells have been fabricated on the nano-texturized substrate for optical property study and photovoltaic performance evaluation. Our measurements have shown significant enhancement on broadband light absorption using these patterned substrates via both geometrical light trapping and plasmonic coupling. Particularly, the enhancement factor reaches as high as 5–30 times at wavelength near the band edge. Numerical simulations confirm the measurements and uncover the mechanisms of the enhancement. More importantly, photovoltaic measurements on nanodent solar cells present improvements of over 31% and 27% in short circuit current and energy conversion efficiency respectively compared with planar solar cells. Therefore, the novel patterned substrates are promising candidates for low cost and high performance thin film solar cells.

Single‐Crystalline p‐Type Zn3As2 Nanowires for Field‐Effect Transistors and Visible‐Light Photodetectors on Rigid and Flexible Substrates

Abstract: Zn3As2 is an important p-type semiconductor with the merit of high effective mobility. The synthesis of single-crystalline Zn3As2 nanowires (NWs) via a simple chemical vapor deposition method is reported. High-performance single Zn3As2 NW field-effect transistors (FETs) on rigid SiO2/Si substrates and visible-light photodetectors on rigid and flexible substrates are fabricated and studied. As-fabricated single-NW FETs exhibit typical p-type transistor characteristics with the features of high mobility (305.5 cm2 V−1 s−1) and a high Ion/Ioff ratio (105). Single-NW photodetectors on SiO2/Si substrate show good sensitivity to visible light. Using the contact printing process, large-scale ordered Zn3As2 NW arrays are successfully assembled on SiO2/Si substrate to prepare NW thin-film transistors and photodetectors. The NW-array photodetectors on rigid SiO2/Si substrate and flexible PET substrate exhibit enhanced optoelectronic performance compared with the single-NW devices. The results reveal that the p-type Zn3As2 NWs have important applications in future electronic and optoelectronic devices.

Fabrication of high-quality ZnTe nanowires toward high-performance rigid/flexible visible-light photodetectors.

Abstract: ZnTe is an important p-type semiconductor with great applications as field-effect transistors and photodetectors. In this paper, individual ZnTe nanowires based field-effect transistors was fabricated, showing evident p-type conductivity with an effect mobility of 11.3 cm(2)/Vs. Single ZnTe nanowire based photodetectors on rigid silicon substrate exhibited high sensitivity and excellent stability to visible incident light with responstivity and quantum efficiency as high as 1.87 × 10(5) A/W and 4.36 × 10(7)% respectively and are stable in a wide temperature range (25-250 °C). The polarization-sensitivity of the ZnTe nanowires was studied for the first time. The results revealed a periodic oscillation with the continuous variation of polarization angles. Besides, flexible photodetectors were also fabricated with the features of excellent flexibility, stability and sensitivity to visible incident light. Our work would enable application opportunities in using ZnTe nanowires for ultrahigh-performance photodetectors in scientific, commercial and industrial applications.

Single-crystalline metal germanate nanowire–carbon textiles as binder-free, self-supported anodes for high-performance lithium storage

Abstract: Single-crystalline metal germanate nanowires, including SrGe4O9, BaGe4O9, and Zn2GeO4 were successfully grown on carbon textile via a simple low-cost hydrothermal method on a large scale. The as-grown germanate nanowires–carbon textiles were directly used as binder-free anodes for lithium-ion batteries, which exhibited highly reversible capacity in the range of 900–1000 mA h g−1 at 400 mA g−1, good cyclability (no obvious capacity decay even after 100 cycles), and excellent rate capability with a capacity of as high as 300 mA h g−1 even at 5 A g−1. Such excellent electrochemical performance can be ascribed to the three-dimensional interconnected conductive channels composed of the flexible carbon microfibers, which not only serve as the current collector but also buffer the volume change of the active material upon cycling. Additionally, the one-dimensional nanostructures grown directly on the carbon microfibers also ensure fast charge carrier (e− and Li+) transport, large surface areas, better permeabilities, and more active sites, which also contributed to the improved electrochemical performance.

Highly Reversible Lithium Storage in Hierarchical Ca2Ge7O16 Nanowire Arrays/Carbon Textile Anodes

Abstract: Aligned Ca2Ge7O16 nanowire arrays were successfully grown on carbon textiles to form hierarchical 3D structures by using a facile hydrothermal method on a large scale. Typical Ca2Ge7O16 nanowires are single crystals that show preferred growth along the [001] direction. The 3D hierarchical structures were used as binder-free anodes for lithium-ion batteries, which showed the features of highly reversible capacity (900-1100 mA h g(-1) at a current density of 300 mA g(-1)), remarkable cycling stability, even over 100 cycles, and good rate capability, with a capacity of about 500 mA h g(-1) at 3 A g(-1). Furthermore, highly bendable full cells were also fabricated, which showed high flexibility, with little voltage change after bending 600 times, and superior temperature tolerance within the range 4-60 °C, thus demonstrating their promising potential for applications in high-performance lithium-ion batteries.

Laterally Emitted Surface Second Harmonic Generation in a Single ZnTe Nanowire

Abstract: We report a direct observation on the laterally emitted surface second harmonic generation (SHG) in a single ZnTe nanowire. The highly directional surface SHG radiates vertically to the nanowire growth-axis with a high conversion efficiency of 5 × 10–6 and a low divergence angle of 4°. Polarization state, emission intensity, and direction of the surface SHG are found to be dependent on the polarization of the pumping laser, which is further confirmed by numerical simulations. The laterally emitted surface SHG with a high efficiency and low divergence angle has great potential for short-wavelength nanolasers, nonlinear microscopic imaging, and polarization-dependent photonic integrating.

Selective synthesis of Sb2S3 nanoneedles and nanoflowers for high performance rigid and flexible photodetectors

Abstract: Needle-like and flower-like antimony sulfide nanostructures were synthesized and applied for both rigid and flexible photodetectors. Rigid photodetectors based on both nanostructures have the features of linear photocurrent characteristics, low linear dynamic range and good sensitivity to light intensity. Especially, the rigid Sb2S3 nanoflowers photodetector has high photoresponse characteristics and its response time and decay time were found to be relatively fast as 6 ms and 10 ms respectively. The flexible Sb2S3 nanoflowers photodetector has high flexible, light-weight and adequate bendability with a response time of about 0.09 s and recovery time of 0.27 s. Our results revealed that the rigid and flexible photodetectors based on Sb2S3 nanostructures have great potential in next generation optoelectronic devices.

Contact printing of horizontally aligned Zn2GeO4 and In2Ge2O7 nanowire arrays for multi-channel field-effect transistors and their photoresponse performances

Abstract: The ternary oxides, Zn2GeO4 and In2Ge2O7 nanowires, are promising n-type semiconductors with outstanding transport properties for high performance electronic devices. By using the direct contact printing process, we reported the assembly of horizontally aligned Zn2GeO4 and In2Ge2O7 nanowire arrays to be used as building blocks for high performance multi-channel field-effect transistors. The as-fabricated multi-channel transistors exhibited higher voltage stability and repeatability than their single nanowire based counterparts. The effective mobilities of the multi-channel field-effect transistors were calculated to be 25.44 cm2 V−1 s−1 and 11.9 cm2 V−1 s−1, comparable to the single-channel FETs. The as-fabricated multi-channel transistors were also used as high performance photodetectors, exhibited a high sensitivity to ultraviolet light illumination with a photoconductive gain and quantum efficiency as high as 1.034 × 105 and 1.032 × 107% for Zn2GeO4 nanowires and 2.58 × 105 and 2.617 × 107% for In2Ge2O7 nanowires.

Contact printing of horizontally-aligned p-type Zn₃P₂ nanowire arrays for rigid and flexible photodetectors.

Abstract: Zn(3)P(2) is an important p-type semiconductor with the ability to detect almost all visible and ultraviolet light. By using the simple and efficient contact printing process, we reported the assembly of horizontally-aligned p-type Zn(3)P(2) nanowire arrays to be used as building blocks for high performance photodetectors. Horizontally-aligned Zn(3)P(2) nanowire arrays were first printed on silicon substrate to make thin-film transistors, exhibiting typical p-type transistor behavior with a high on/off ratio of 10(3). Besides, the Zn(3)P(2) nanowire array based devices showed a substantial response to illuminated lights with a wide range of wavelengths and densities. Flexible photodetectors were also fabricated by contact printing of horizontally-aligned Zn(3)P(2) nanowire arrays on flexible PET substrate, showing a comparable performance to the device on rigid silicon substrate.

Structural engineering for high energy and voltage output supercapacitors.

Abstract: High capacitance and high output voltage are two important research focuses of electrochemical supercapacitors. Herein we present two novel designs (laminated and tandem) of coin-cell supercapacitors based on a textile coated with active material. The fabric electrodes were prepared by dipping the non-woven cloth into a dispersion of carbon nanotubes and subsequent MnO2 electrodeposition. In the lamination configuration, several pieces of active-material-coated cloth were laminated to construct individual electrodes that enable fold-increased areal capacitances and excellent cycling stability. In the tandem structure, individual cells with solid-state electrolyte (polyvinyl alcohol/H3PO4) sandwiched between the fabric electrodes were stacked together to form a single device. The assembled device composed by ten unit cells was demonstrated to drive four LED digital screens in series with 10 V output.

Two-photon pumped lasing in a single CdS microwire

Abstract: We report the two-photon absorption induced lasing performance in a single CdS microwire under the excitation of a femtosecond pulse laser with a wavelength of 800 nm. Sharp lasing peaks are centered at 523 nm with an average linewidth of 0.4 nm, indicating a high quality factor of 1300. The lasing emission is highly dependent on the polarization direction of the excitation light and the optimized lasing threshold is estimated to be 3.3 mJ/cm2 as the polarization direction is parallel to the microwire axis. Furthermore, the polarization-dependent lasing effect is confirmed by performing the finite-difference time-domain method.

High-Mobility Solution-Processed Amorphous Indium Zinc $\hbox{Oxide/In}_{2}\hbox{O}_{3}$ Nanocrystal Hybrid Thin-Film Transistor

Abstract: High-performance thin-film transistors with amorphous indium zinc oxide (IZO) films was deposited by embedding indium oxide nanocrystals (In2O3 NCs) into IZO films based on a sol-gel process. Excellent electrical properties have been demonstrated, including a field-effect mobility value of 32.6 cm2·V-1·s-1 and an on-off ratio of 107 , which were obtained at 1 mol% In2O3 NCs in amorphous IZO films. Our findings demonstrate the feasibility of low-temperature sol-gel-based oxide semiconductor transistors, which is more cost-effective compared with conventional fabrication techniques but with comparable performance.