Cost-effective Chemical Bath Deposition Research Articles

Optimization of deposition time on structural, morphological, and optical properties of Cd1-xZnxS nanocrystalline thin films

In this work, Cd1-xZnxS nanocrystalline thin films have been synthesized over a glass substrate by a simple and cost-effective Chemical Bath Deposition (CBD) technique at various deposition time keeping other deposition parameters constant. The structural, morphological, and optical properties are studied by incorporating a range of characterization techniques, including X-ray diffraction (XRD), Field Emission Scanning Electron Microscopes (FESEM), Energy Dispersive X-rays (EDX), and UV–Visible spectrophotometers (UV–Vis). The films have been deposited at five different deposition time in the range from 30 mins to 150 mins to record the changes which address in depth the structural, morphological and optical properties. Empirical fitting equations have also been developed to obtain a more quantitative analysis of the effect of deposition time. The results obtained in this work are compared with some recent reported works for performance analysis of the buffer layer. The proposed buffer layer deposited at 30 mins not only attains all the desirable qualities required for maximum extraction of solar energy but also a low-cost and environment friendly option, making it a potential candidate for solar cell and optoelectronic applications.

Surface dynamics and electrochemical examination of Co3O4 films by iron doping

This study focused on Co3O4 films, which were prepared by cost-effective chemical bath deposition on In:SnO2 (ITO) substrates with iron doping concentrations ranging from 2 to 6 mol %. Structural properties were investigated by XRD as well as nanotexture of Fe: Co3O4 films was captured via SEM and detailed fractal analysis was analyzed in each prepared film. Effective using of prepared Fe: Co3O4 electrodes for electrochemical charge storage applications has been examined by using CV and EIS. From x-ray patterns, spinel cubic structure of Co3O4 was observed in all samples, while peaks with Co2O3 and substrate indexed peaks were also shown. Pure and iron doped Co3O4 surfaces have spherical agglomerative forms while porous structures were observed in 4% Co3O4 samples. Redox peaks induced by Faradaic reactions in the CV plots present pseudo- capacitive nature for all electrodes and improves charge transfer process in 4% Co3O4 and 6% Co3O4 from EIS measurements. Additionally, using scaling theory, the coverage ratio, fractal dimensions, cluster sizes and interface critical exponent values of the superficial hetero morphology of the samples are calculated. While the coating rate decreases according to the iron concentration, fractal dimensions increase. However, as the number of clusters increases, the average cluster size decreases. The interface critical exponent value shows an irregular change.

Field emission from two-dimensional (2D) CdSSe flake flowers structure grown on gold coated silicon substrate: An efficient cold cathode.

Field emission finds a vital space in numerous scientific and technological applications, including high-resolution imaging at micro- and nano-scales, conducting high-energy physics experiments, molecule ionization in spectroscopy, and electronic uses. A continuous effort exists to develop new materials for enhanced field emission applications. In the present work, two-dimensional (2D) well-aligned CdSSe flake flowers (CdSSe-FFs) were successfully grown on gold-coated silicon substrate utilizing a simple and affordable chemical bath deposition approach at ambient temperature. The time-dependent growth mechanism from nanoparticles to FFs was observed at optimized parameters such as concentration of precursors, pH (~11), deposition time, and solution temperature. The crystalline nature of CdSSe-FFs is confirmed by high-resolution transmission electron microscopy (HRTEM) results, and selected area electron diffraction (SAED) observations reveal a hexagonal crystal structure. Additionally, the CdSSe-FFs thickness was confirmed by TEM analysis and found to be ~20-30 nm. The optical, photoelectric, and field emission (FE) characteristics are thoroughly explored which shows significant enhancement due to the formation of heterojunction between the gold-coated silicon substrate and CdSSe-FFs. The UV-visible absorption spectra of CdSSe-FFs show enhanced absorption at 700 nm, corresponding to the energy band gap (Eg) of 1.77 eV. The CdSSe-FFs exhibited field emission and photosensitive field emission (PSFE) characteristics. In FE study CdSSe-FFs shows an increase in current density of 387.2 μ A cm-2 in an applied field of 4.1 V m-1 which is 4.08 fold as compared to without light illumination (95.1 μ A cm-2). Furthermore, it shows excellent emission current stability at the preset value of 1.5 μA over 3 h with a deviation of the current density of less than 5% respectively. RESEARCH HIGHLIGHTS: Novel CdSSe flake flowers were grown on Au-coated Si substrate by a cost-effective chemical bath deposition route. The growth mechanism of CdSSe flake flowers is studied in detail. Field emission and Photoluminescence study of CdSSe flake flowers is characterized. CdSSe flake flowers with nanoflakes sharp edges exhibited enhanced field emission properties.

Binderless synthesis of hierarchical, marigold flower-like NiCo2O4 films for high-performance symmetric supercapacitor

The facile and cost-effective chemical bath deposition method is employed for the binder-free synthesis of NiCo2O4 marigold flower-like nanostructures on a flexible stainless-steel substrate. Binderless and surfactant-free synthesis of NiCo2O4 films for supercapacitor application is a crucial part of this synthesis process. The effect of reaction times on the deposition of NiCo2O4 nanostructured films has been discussed briefly based on the electrochemical performance and surface morphology of films. The reaction time is varied as 2, 4, 6, and 8 h. The prepared films were analyzed by structural and morphological characterizations. The time-dependent significant change in morphology of NiCo2O4 films is discussed in detail. The development of the Marigold-like flowers from wheat grain-like nanostructures has been observed for increasing reaction time. The film deposited at 6 h reaction time (NCO-6 electrode) showed better specific capacitance of 1277 F/g at 5 mA/cm2, which retained about 95 % after 10,000 cycles. The NiCo2O4 film exhibited a 0.7 V potential window with the maximum energy and power density of 86 Wh/kg and 2333 W/kg, respectively. The fabricated aqueous symmetric device i.e., NCO//NCO showed energy density and power density of 16.4 Wh/kg and 275.5 W/kg, respectively. The fabricated device shows 90.5 % retention in performance after 5000 cycles. These results revealed that NiCo2O4 can be a better electrode material for energy storage devices.

Chemical characteristics via quantitative photoelectron analysis of chemical-solution-deposited yttrium oxide thin films for metal-insulator-metal capacitor applications

A cost-effective chemical bath deposition coupled with an annealing methodology is presented for obtaining yttrium oxide (Y2O3) thin films. The resultant thin films are homogeneous, free of pinholes, and show a relatively low surface roughness. The detailed characterization of the as-deposited thin film and the determination of optical, structural, and chemical characteristics of the films upon thermal transformation at 500 °C for 2 h was done with thermogravimetric analysis, X-ray diffraction, UV–Vis spectroscopy, surface topology analysis, and X-ray photoelectron spectroscopy. The results reveal that the as-deposited thin film is composed of an amorphous YOOH compound intrinsic to the synthesis process. However, with annealing, it is crystallized and transformed into a Y2O3 thin film showing a high optical transparency. The characteristics of the film are found to be influenced by the Y‒OH and Y‒O content with direct influence on the shape of the photoelectron spectra of the thin films showing a binding energy downshift of 1.6 eV from the 158.84 eV peak position found for the YOOH sample after annealing. The estimated surface roughness for the as-deposited YOOH and annealed Y2O3 samples resulted in 2.7 and 3.8 nm, respectively. The electrical characteristics and potential performance as a dielectric layer have been assessed in a Metal-Insulator-Metal configuration, where the acceptable values for leakage current in the 6 × 10−4 − 3 × 10−6 A/cm2 range and a capacitance of 218 and 80 nF/cm2 were measured for the YOOH and Y2O3 thin films, respectively. The latter indicates that these films are suitable candidates for gate dielectric transistor applications with the advantage of them being films produced via an economical and technically simple scalable process.

Chemically Synthesized ZnO Thin Film Electrode for Supercapacitor Application

In this paper, we synthesized zinc oxide (ZnO) thin film by using a cost effective chemical bath deposition technique (CBD) at 90∘C. The as-deposited ZnO films exhibited polycrystalline in nature. The FESEM image shows growth of nanorods about 0.2[Formula: see text][Formula: see text]m length. The Raman spectrum was recorded using frequency of 532[Formula: see text]nm with excited line Nd-YAG laser. The optical band gap of ZnO thin film obtained 3.37[Formula: see text]eV. The value of RMS roughness is determined by atomic force microscopy (AFM), found to be 34[Formula: see text]nm. The supercapactive studies were determined in 2[Formula: see text]M[Formula: see text]KOH aqueous electrolyte by means of cyclic voltammetry and charge–discharge technique. ZnO exhibited maximum specific capacitance of ZnO 204[Formula: see text]F/g at the scan rate of 5[Formula: see text]mV/s.

Photodegradation of Rhodamine-B Dye under Natural Sunlight using CdO

The present study includes synthesis of CdO thin film by simple and cost effective chemical bath deposition method. Cadmium monochloroaceatate were used for preparation of CdO thin film. The structural, optical properties of CdO thin film were investigated with the help of X-ray diffraction (XRD) and UV-Vis NIR double beam spectrometry. The XRD studies revealed that annealed thin film shows crystalline in nature having 48.4 nm in size. The optical band gap of thin film was found to be 2.13 eV. Scanning Electron Microscopy (SEM) images shows sphere like structure which is closely arranged with each other. The presence of functional group was confirmed by Fourier Transform Infra Red (FTIR). Brunauer–Emmett–Teller (BET) surface area analysis confirm formation of a mesoporous CdO with 6.01 m2/g surface area and 31.96 nm average pore diameter. The photocatalytic activity of prepared thin film was checked by using Rhodamine-B as a model dye under natural sunlight and found to be 48%. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Improving electrochromic performance of porous nickel oxide electrode via Cu doping

Porous Cu-doped NiO films were fabricated by a cost-effective chemical bath deposition method. The structural characterizations show that Cu doping significantly increase the porosity of the electrodes and the ratio of Ni3+/Ni2+, which are conducive to the electrolyte penetration and chemical reactivity. But the electrochromic and electrochemical behaviors show a nonmonotonic change with Cu doping content. The transmittance modulation increases from 54.56% to 67.72% with the doped Cu/Ni molar ratio increasing from 0 to 0.5%, and the corresponding coloration/bleaching time reduces from 10.4/7.9 s to 6.0/4.1 s, then gets worse with the further Cu doping because of the ionized impurity scattering effects. The optimal electrode with Cu doping of 0.5% show a good cyclic stability, which maintains 84.4% of ΔT after 200 discharge/charge cycles, the excellent cycle performance can be attributed to the inhibition of the irreversible transition of Ni2+ to Ni3+ by the doping of Cu during cycling.

Annealing Assisted Structural Modifications in CdS Thin Films

The present article deals with synthesis of CdS thin films using cost effective chemical bath deposition method and study effect of annealing over the structural properties using X-ray diffraction pattern (XRD). The XRD pattern revealed shift in peak position and variation in intensity upon annealing at different temperatures; this may be attributed to annealing assisted modifications in composition of the thin films. The as deposited CdS thin films represents peaks corresponding to (002), (101), (111) and (110) which in case of annealed samples at 200 and 400oC get modified and slightly shifted with rising some new peaks corresponding to (200) and (001) respectively. The crystallite size of the CdS thin films upon annealing is observed to be increased this may be co-related to the fact energy induced grain growth.

Solution-Processable Growth and Characterization of Dandelion-like ZnO:B Microflower Structures

Intrinsic and dandelion-like microflower nano-rod structures of boron-doped ZnO thin films were synthesized with an ecofriendly and cost-effective chemical bath deposition technique from an aqueous solution of zinc nitrate hexahdyrate [Zn(NO3)2.6H2O] as a precursor solution and boric acid as a doping solution. The boron concentrations were 0.1, 0.3, 0.5, 1.0, 3.0, 5.0, and 7.0 by volume. Scanning electron micrographs showed that doping with boron appears to hinder the vertical alignment of crystallites. Additionally, independent hexagonal nano-rod structures were observed to coalesce together to form dandelion-like structures on the film’s surface. The atomic ratio of the elements was determined via the X-ray photoemission spectrum technique. There were no substantial changes in the vibration structure of the film upon doping in terms of the Raman spectra. The optical band gap of ZnO (3.28 eV) decreased with B doping. The band gap of the ZnO:B film varied between 3.18 and 3.22 eV. The activation energy of the ZnO was calculated as 0.051 eV, whereas that of the ZnO:B film containing 1.0% B was calculated as 0.013 eV at low temperatures (273–348 K), versus 0.072 eV and 0.183 eV at high temperatures (348–523 K), respectively. Consequently, it can be interpreted that the 1% B-doped ZnO, which has the lowest activation energy at both low and high temperatures, may find some application areas such as in sensors for gases and in solar cells.

Structure, morphology, and photoresponse characteristics dependence on substrate nature of grown π-SnS films using chemical bath deposition

Thin films suffer from insufficient strength and cannot be made self-holding. Hence, more convenient fabrication process onto proper holding substrate material is needed to achieve well-matching with the film material. This research work aims to investigation of the influence of the substrate nature on the evolution of the structure, morphology and photoresponse characteristics of tin monosulfide (π-SnS) films. The π-SnS films have been deposited through the simple and cost-effective chemical bath deposition technique onto PET, glass, and n-type Si wafer substrates. X-ray diffraction and Raman analyses confirm that the films crystallize within a cubic structure of SnS phase with polycrystalline nature. Field emission scanning electron microscopy observations reveal that the surfaces of PET and Si substrates are covered with irregular spherical grains with the presence of some nanoflakes. Conversely, the surface of the glass substrate is found to be entirely covered with high-density assembled nanoflakes. The dark current value has been found to increase significantly from pA up to μA; at 3 V bias voltage, the dark current values are 55 pA, 850 pA, and 3.5 μA for the photodetectors based on PET, glass, and Si substrates, respectively. Moreover, upon the near-infrared illumination at 750 nm, the fabricated photodetectors demonstrate good sensitivity and photoresponse time; at 3 V bias voltage, the sensitivity values are found to be 2591, 697, and 2982 for photodetectors onto PET, glass, and Si substrates, respectively. The obtained results demonstrate the critical role of substrate nature on the characteristics of the as-grown π-SnS films.

Characterization of TiO2 fabricated by the cost-effective CBD method

The current paper is about the descriptions of the topography and compositional, optical and structural characteristics of cost-effective and non-toxic titanium dioxide (TiO2) thin film deposited using the chemical bath deposition (CBD) method on a glass substrate for the transparent conductive oxide layer in solar cell application. The specimens were characterized by various instrumentation techniques such as X-ray diffraction (XRD), ultraviolet (UV)–visible–near-infrared spectrometry and field emission scanning electron microscopy (FESEM) coupled with elemental analysis (energy-dispersive X-ray spectroscopy). The XRD results indicated a perfect polycrystalline titanium dioxide phase. UV spectrophotometry of the titanium dioxide thin film found a bandgap of 3.2 eV. At a glance, the morphology of the film by FESEM shows that the deposited film is crack-free and is deposited uniformly. The thickness of titanium dioxide is measured to be approximately equal to 100 nm.

CsPbBr3 and Cs4PbBr6–CsPbBr3 composite perovskite sensitization of 3D-ZnO nanostructures for enhanced photoluminescence emission

This study reports a seeding-layer free synthesis of nanostructured three-dimensional zinc oxide (3D-ZnO) thin films via a simple and cost-effective chemical bath deposition method (CBD) followed by their sensitization with inorganic perovskite halide semiconductors for luminescence-based applications. The emission abilities of pristine ZnO nanostructures have been enhanced with the incorporation of CsPbBr3 in the cubic crystal phase, which is proven to be a highly stable member of the inorganic halide perovskite family. Additionally, the transformation of CsPbBr3 nanocrystals into Cs4PbBr6–CsPbBr3 composite structure has been attained by altering the (i) CsBr content and (ii) crystallization temperature during the perovskite synthesis step, resulting in a remarkable luminescence increase for the overall structure by ~17 folds. A detailed evaluation of defect contents and carrier lifetimes of pristine and perovskite deposited ZnO thin films have been conducted via time-resolved photoluminescence spectroscopy showing an improved electron transfer especially for Cs4PbBr6–CsPbBr3 deposited ZnO thin films.

Morphological and Optical Studies of ZnO-Silica Nanocomposite Thin Films Synthesized by Time Dependent CBD

ZnO-SiO2 nanocomposite thin films were synthesized using a facile and cost-effective chemical bath deposition for different growth durations, under alkaline conditions on microscopic glass slides. Effect of deposition time on the morphological and optical properties were thoroughly investigated using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), transmittance and time-resolved photoluminescence studies, etc. XRD patterns confirmed the formation of ZnO and diffused ZnO-Silica phases of hetero-structures at a particular growth time starting from the amorphous silica phase. SEM micrographs revealed an appreciable change in morphology of the particles with increasing growth time. Uniform porous films with improved surface coverage resulted on the substrate after an incubation period of 2 h. The EDX spectra confirmed that the thin films composed of ZnO and silica co-exist without any other impurities. It was observed that transmittance of the films decreased with increase in growth duration, whereas a slight variation in band gap was observed. The observed diminutive red shift in the band gap is due to a slight change in the transmission cut off edge. Laser-induced, time-resolved photoluminescence studies were conducted using pulse excitation in the nano-sec time domain. It showed an appreciable decrease in deep defect level emission at higher deposition duration, which arose due to unintentional doping in ZnO, creating a large number of native defects.

Heat induced crystallization of CBD deposited copper sulphide thin films

CuS thin films were prepared by using cost effective chemical bath deposition method at 353 K. Effects of thermal treatment on the structural and optical properties of prepared films were investigated using XRD technique, UV–Vis spectroscopy, FTIR spectroscopy and Raman spectroscopy by annealing at 473 K. It has been found that on annealing amorphous CuS were thermally converted to crystalline CuS thin films. Optical band gap was decreased on annealing due to quantum confinement effect. The presence of traces of Cu2S phase in the CuS matrix in the thin film was revealed by Raman spectroscopy.

Incorporation of Zinc Oxide on Macroporous Silicon Enhanced the Sensitivity of Macroporous Silicon MSM Photodetector

In this study, metal-semiconductor-metal (MSM) photodetectors (PDs) was fabricated on the macroporous silicon substrate, (mPS) followed by growth of zinc oxide (ZnO) on the mPS substrate (ZnO/mPS) with addition of nickel (Ni) contact in finger mask pattern. The mPS was formed by electrochemical etching technique with an estimated etching time of 15 min by a continuous current flow of 25 mA. The ZnO nanostructures were synthesized by cost-effective chemical bath deposition (CBD) process. Field Effect Scanning Electron Microscopy (FESEM) and X-ray Diffractometer (XRD) revealed the randomly distributed of upper-morphologies and crystalline properties of x-shaped mPS as well as the distribution of ZnO/mPS. A good Schottky contact with superior photoconductivity, photo-responsivity, and photo-sensitivity have been demonstrated from these MSM PDs under illumination of 383 nm and 422 nm light sources. An enhanced photoconductivity at 422 nm had been demonstrated from Ni/ZnO/mPS/Ni PD which was believed due to the incorporation of energy properties at ZnO/mPS interface with a greater energy band gap of 3.15 eV. The responsivity of Ni/mPS/Ni PD at 383 nm and 422 nm were 0.088 A W−1 and 0.171 A W−1, respectively. While the Ni/ZnO/mPS/Ni PD shows the double photo-responsivity for both wavelengths, with the values of 0.160 A W−1 and 0.385 A W−1, respectively. In overall, the incorporation of ZnO/mPS structure drawn a great significance in PDs performance due to unique tunable photo-responsivity, higher sensitivity, and faster rise and decay time which attributed to the swift recombination process.

Nanostructured δ-MnO2/Cd(OH)2 Heterojunction Constructed under Ambient Conditions as a Sustainable Cathode for Photocatalytic Hydrogen Production

In this study, we report the deposition of a thin layer of Cd(OH)₂ over δ-MnO₂ deposited on a fluorine-doped tin oxide (FTO) glass substrate, thereby forming a heterojunction with synergistic effects. Electrodes fabricated by a room-temperature, facile, and cost-effective chemical bath deposition method display enhanced photoactivity when used as cathodes for the hydrogen evolution reaction (HER) in a photoelectrochemical cell, with an observed photocurrent of 0.3 mA/cm² at 0 V vs reversible hydrogen electrode (RHE). The electrodes also showcase a dark electrocatalytic current of 2.9 mA/cm² without illumination. The δ-MnO₂/Cd(OH)₂ nano-heterostructure is analyzed thoroughly via various physicochemical, optical and electrochemical methods to understand the phenomena involved in the conduction characteristics. The enhanced photoconductivity is attributed to effective charge separation and transport by the presence of synergistic materials with optimal band gap energies. These results show promise for the use of birnessite-based materials as sustainable electro- or photocatalysts for the hydrogen evolution reaction.

One-pot facile synthesis of nanorice-like structured CuS@WS2 as an advanced electroactive material for high-performance supercapacitors

Binder-free nanorice-like featured CuS@WS2 structures have been synthesized using a simple and cost-effective chemical bath deposition approach and their application as electroactive material for high-performance supercapacitors. The surface properties of morphology, structure and composition of the as-prepared electrodes are examined using the scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The nanorice-like featured CuS@WS2 electrode exhibits nanorice-like structures, which provides the abundant active sites for redox reactions and facilitates the electrolyte diffusion. The electrochemical performance of the supercapacitor electrodes was examined by cyclic voltammetry and galvanostatic charge–discharge studies. From the electrochemical tests, the CuS@WS2 electrode exhibits a higher specific capacitance (Cs) of 887.15 F g−1 at a current density of 3.75 A g−1 with greater energy density and excellent rate capability compared to bare CuS (588.0 F g−1) and WS2 (19.40 F g−1) electrodes. Overall, these results demonstrate that the as-synthesized CuS@WS2 could be a promising material for next-generation high-performance electrochemical energy storage applications.

Synthesis and characterization of the chemically deposited SnS1−x Sex thin films: structural, linear and nonlinear optical properties

This article reported the synthesis of tin sulfide selenide (SnS1−x Sex) thin films with different compositions (0 ≤ x ≤ 1) using a cost-effective chemical bath deposition technique. The structural properties of the chemically synthesized SnS1−x Sex thin films were analyzed by means of the X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The XRD results demonstrate that all the chemically synthesized SnS1−x Sex thin films are polycrystalline and displayed an orthorhombic phase corresponding to the different compositions. The compositional elements of the SnS1−x Sex thin films were investigated via an energy dispersive X-ray analysis (EDAX). The optical study on the SnS1−x Sex thin films displayed that the chemically deposited SnS1−x Sex films exhibited a direct allowed optical transition and by increasing the Se content the magnitudes of the direct bandgap were decreased from 1.41–1.23 eV while the Urbach energy was increased. The effect of composition on the skin depth δ, absorption coefficient α, linear refractive index n and the static refractive index no of the SnS1−x Sex thin films was studied. Additionally, the results displayed that there is an improvement in the magnitudes of the nonlinear refractive index n2, optical conductivity, third-order nonlinear optical susceptibility $$\chi^{\left( 3 \right)}$$ and the electrical conductivity of the SnS1−x Sex thin films occurred by increasing the selenium content.

Facile synthesis of nanoparticles anchored on honeycomb-like MnCo2S4 nanostructures as a binder-free electroactive material for supercapacitors

Abstract In the present study, nanoparticles filled with honeycomb-like MnCo2S4 (MCS) nanostructures are prepared successfully on the surface of nickel foam using a simple and cost-effective chemical bath deposition method and can be used as a promising electroactive material for high performance supercapacitor applications. The electrochemical behavior of the as-prepared electroactive materials was studied by the cyclic voltammetry, galvanostatic charge/discharge, electron impedance spectroscopy. The crystalline phase, structure, morphology and composition of the as-prepared electroactive materials were analyzed by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The performance of the as-prepared electroactive materials was carried out in a 3 M KOH electrolyte in the three-electrode system. The unique nanoparticle structures enable and provides the more efficient pathways for the rapid mobility of electrons and ions. As a result, the as-prepared binder-free MCS electrode exhibits a higher specific capacity of 129.7 mA h g−1 at 1 A g−1, superior rate capability of 88.51% after 4000 cycles and excellent cycling stability of 87.81% respectively, which are much higher than that of MCO electrode. These results reveal that the as synthesized MCS electrode found to be the most promising candidate for high-performance supercapacitor applications.