As-prepared Films Research Articles

Preparation of Ag@lignin nanotubes for the development of antimicrobial biodegradable films from corn straw

Current environmental and energy issues have attracted considerable attention from industries, governments, and academia. Developing alternative diverse petrochemical-based plastics with biodegradable packaging materials from renewable resources is critical for ensuring both sustainability and safety. In this study, biodegradable films are fabricated from corn straw via a facile sol-gel process. Furthermore, these films are imbued with antimicrobial properties by coupling with silver@lignin nanotube hybrid antibacterial agents, formed via the in situ reduction of silver ions into elemental silver by lignin (mild reducing agent), followed by the self-assembly of lignin molecules into nanotubes assisted by an aqueous silver nitrate electrolyte solution. The developed antibacterial corn straw film exhibits strong mechanical and antibacterial properties, with a tensile strength and elongation at break of 68.7 MPa and 11.3 %, respectively, under optimum conditions and antibacterial activity against Escherichia coli and Staphylococcus aureus of 99.9 % and 97.2 %, respectively. The as-prepared corn straw films exhibit high hydrophobicity and ultraviolet resistance. The morphology, structure, and thermal properties of the corn straw films were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and thermogravimetric analysis. This study provides a straw-based biodegradable packaging film with antimicrobial properties.

Performance analysis of P-SnS thin films fabricated using CBD technique for photo detector applications

In the present work, SnS thin films were prepared using the CBD technique at room temperature and varying annealing temperaturesfrom300 to 450 °C for photo detector applications. The prepared samples were characterized using different techniques for analyzing the structural, optical, morphological, and photo sensing properties of the samples. From XRD analysis, the diffraction pattern of all the prepared thin films shows the pristine SnS phase of the samples possessing an orthorhombic phase without the presence of any impurity phases. Among the fabricated thin films, the SnS thin film annealed at a temperature of 350 °C reveals the highest crystallite size. The Raman results showed the vibrational modes of SnS films and with the increase in growth temperature, the peaks are slightly shifted towards the lower wavelength region. Morphological results show that the SnS thin films exhibit a uniform morphology of 2-D petal-like morphology with different sizes. The UV-vis spectroscopic study shows the decrease in the bandgap value of the samples with the increase in annealing temperature. The photo sensing properties of the fabricated samples show the SnS sample annealed at 400 °C has a higherresponsivityvalueof6.40×10⁻²AW⁻¹,externalquantumefficiency(EQE)valueof14.9%, and the detectivity value of 6.05 × 10⁹ Jones. Finally, the transient photo response results suggest that the SnS annealed at 350 °C shows a rise and fall time of 1.5 and 2.5 s compared to the othersampleswhichwouldbebettersuitedforphotodetectorapplications. The electrical conductivity and photo-conductivity of the films increase by more than two orders with increase of film thickness from 170 nm to 915 nm. Hall Effect measurements confirm the p-type nature of the as-prepared SnS thin films.

Optimization of photoelectric properties of transparent conductive B and Ga co-doped ZnO films for electrochromic applications

To improve the performance of electrochromic devices, it is urgently necessary to develop transparent indium-free conductive electrodes with high conductivity and transparency. In this study, thin films of Ga-doped ZnO (GZO) and B–Ga co-doped ZnO (BGZO) were prepared on glass substrates using the plasma-assisted atomic layer deposition (PEALD) technique, and their structural and optoelectronic properties were characterized. It is found that all thin films were consistent with hexagonal fibrous ZnO structure, and the surface morphology of the membrane was homogenous at nanoscale. UV spectroscopy analysis showed that the doping of B and Ga elements could increase the transparency of ZnO films. The electrical properties can be remarkably enhanced by doping with B and Ga elements. Further more, tungsten oxide (WO3) was deposited on the as-prepared BGZO films using magnetron sputtering method. We activated the sample by applying voltage and observed a color transition from transparent to dark blue. It has a modulation range of 65 % in the 633 nm spectrum and a coloring efficiency of 37.8 cm2C-1. This work opens up remarkable new opportunities for developing high-performance transparent conductive electrode in electrochromic devices.

Synthesis of organic-solvent-soluble cellulose and preparation of fluorescent polyurethanes for the detection and removal of Hg+ ions

Modifying cellulose to obtain materials with favorable processing properties and functions is highly significant, especially, for the detection and removal of heavy metal ions. In this study, fluorescent cellulose-based polyurethane (PU) films containing naphthalimide fluorophore were synthesized and could use for the convenient detection and removal of Hg+ ions. Firstly, the microcrystalline cellulose was treated with SOCl2 to convert some -OH groups into -Cl. Simultaneously, a naphthalimide derivative (NAN) with -NH- groups was synthesized. Subsequently, a fluorescent cellulose-based probe (Cel-NAN) was prepared by utilizing the substitution reaction between -Cl on cellulose and -NH- on NAN. Finally, two cellulose-based fluorescent PU films (Cel-NAN-PU1 and Cel-NAN-PU2) were successfully synthesized by reacting the unreacted -OH groups on Cel-NAN with PEG-1000 and HDI/IPDI. These as-prepared PU films could serve as portable fluorescence test papers to Hg+ ions in aqueous solutions. Upon contact with Hg+ ions, the fluorescence was quenched, acting as a “turn-off” probe. Simultaneously, these films could serve as adsorbents for the removal of Hg+ ions from aqueous systems. Cel-NAN-PU1 film exhibited a removal efficiency over 80 % and an adsorption capacity of 8.4 mg·cm−2 for Hg+. These cellulose-based fluorescent PU films possess promising potential in the field of mercury pollution control.

A comparative study of photoelectric performance of Ga2O3 solar-blind photodetectors with symmetric and asymmetric electrodes

Gallium oxide (Ga2O3) thin films were deposited on quartz substrates under different oxygen flow ratios (O2/[O2+Ar], 0%−5%) by radio-frequency (RF) magnetron sputtering technique followed by thermal annealing at 900 °C for 2 h under N2 atmosphere. The influence of the oxygen concentration on the structural and optical characteristics of Ga2O3 thin films was investigated. The Ga2O3 thin films prepared under an oxygen flow ratio of 1% exhibited optimum crystal quality and the lowest oxygen vacancy (VO) concentration according to X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) investigations. All as-prepared polycrystalline Ga2O3 thin film samples exhibited high average transmittance above 87.8% in the visible spectral region and the 0% and 1% thin films had optical bandgap energies of about 4.9 eV. We also fabricated metal−semiconductor−metal (MSM) photodetectors based on 1% Ga2O3 thin films by employing pairs of Ni−Ni symmetrical or Ni−Al asymmetrical interdigitated electrodes. The Ni−Ni photodetector had a high on/off current ratio (Ion/Ioff > 105), a responsivity of 88.7 mA/W, and specific detectivity of 4.81×1010 J at 10 V bias under ultraviolet light-C (UVC) illumination, and the Ni−Al photodetector exhibited self-driven behavior along with short rise and fall times (0.45 s and 0.69 s, respectively).

Optimizing physico-chemical properties of hierarchical ZnO/TiO2 nano-film by the novel heating method for photocatalytic degradation of antibiotics and dye

The design of semiconductor catalysts with excellent photocatalytic properties, stability, recyclability, and good separation for the treatment of polluted water is still challenging. In this paper, the ZnO/TiO2 nano-thin films were fabricated using the magnetron sputtering technique and then heating the underlying ZnO layer and the upper TiO2 layer for their respective optimal heating time, i. e. heating ZnO for 3 h and heating TiO2 for 2 h. The as-prepared films were characterized. The results show that the preferred growth of TiO2 grains along the [001] axis, relatively large specific surface area, and increased amounts of surface oxygen vacancies (OVs) were induced to the heterojunction catalysts through this optimized heating strategy, which boosts the photocatalytic activity of ZnO/TiO2 nano-film. The degradation experiment inndicates that the ciprofloxacin (CIP) removal efficiency can reach 97.3% in 2 h duration, which was higher than that of the samples annealed for the same periods. Meanwhile, the prepared ZnO/TiO2 photocatalytic film exhibited favorable stability of 95.5% degradation efficiency after the fourth run and general applicability for the photodegradation of various contantains, whih removed 99.5% of ofloxacin (OFX) and 77.6% of tetracycline (TC) in 2 h and 94.1% of Rhodamine B (RhB) in 1 h. This work is expected to yields a novel insight into the production of heterojunction photocatalysts with excellen ability for photocatalytic degradation of pollutants in the practical industry.

Effect of Annealing Temperature Variation on Al-Doped Nickel Oxide Thin-Film Synthesized by Dip-Coating Technique

Aluminum-doped NiO thin films were generated on glass substrates by dip coating at different temperatures (400 to 500 °C) using 0.05 M of the precursor nickel acetate. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the structural and morphological aspects of the films. UV-visible spectroscopy was utilized to assess the optical properties of the films, and the energy band gap was confirmed to be 3.42,3.6, and 3.8 eV for as-prepared and thin films, respectively. Photoluminescence (PL) measurements were used to investigate electronic faults. The XRD lines of the transferred Al-doped NiO were strengthened due to the fact the film's temperature content increased due to the improved crystalline structure. This research article focuses on the optical properties and morphologies of thin films which have been deposited. Crystalline proportions of the thin films that were deposited were determined using the Debye-Scherer formula. The outcomes were computed after taking measurements of absorbance (A), transmittance and Band Gap.

Fabrication of CuO/UiO-66-NO2/TFC-PA catalytic film for the removal of organic contaminant

CuO/UiO-66-NO2/TFC-PA catalytic film was successfully fabricated by embedding CuO/UiO-66-NO2 catalyst nanoparticles onto the PA layer of TFC-PA film through the interfacial polymerization technique. The as-prepared catalytic films were characterized by various techniques such as XRD, FTIR, ATR-IR, EDX, UV-Vis DRS, and N2 adsorption-desorption isotherm. The photocatalytic activity was evaluated by the decomposition of Methylene blue (MB) dye in the aqueous phase under visible light irradiation. The results indicated that the highest removal efficiency achieved was 98.5%, which was consistent with the pseudo-first-order kinetics. Additionally, the proposed mechanism for the charge transfer process was based on the results of radical scavenging experiments, which showed that superoxide and hydroxyl radicals were the predominant reactive species. Finally, the catalyst was stable and could be reused at least four times without loss of photocatalytic activity.

Multifunctional carbon dots reinforced gelatin-based coating film for strawberry preservation

The development of safe, non-toxic, multifunctional nano preserved materials with excellent performance has become a hot research topic. Multifunctional Sophora Japonica extract (95% rutin)-derived carbon dots (R-CDs) were prepared by hydrothermal method. The π-π conjugation structure of R-CDs enabled them UV broadband absorption properties. The excellent antioxidant properties of R-CDs were attributed to the presence of the sp2 carbon in core and a large number of hydroxyl groups at the edges, and their degradation rate of potassium permanganate and scavenging activity of superoxide anion radical were better than that of ascorbic acid. The presence of CO bond may be the site for the generation of reactive oxygen species (ROS) and thus they could kill Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis) and Listeria monocytogenes (L. monocytogenes) at a concentration of 2 mg/mL and inhibited the growth of fungi (Botrytis cinerea). Then R-CDs were uniformly dispersed in gelatin-based solution, and the as-prepared films had smooth surface, good hydrophilicity, strong mechanical properties and good biocompatibility. With the increase of R-CDs addition, the tensile strength increased and then decreased, and the elongation at break rose to 358%. The film inherited the broadband UV absorption, antioxidant and antibacterial properties of R-CDs. The storage period of strawberries was prolonged after coating. The variety and abundance of microorganisms on the surface of strawberries was reduced and the growth of harmful bacteria was inhibited. This work provides more possibilities for the application of nanomaterials in fruit preservation.

Release study of polyphenols from polyvinyl alcohol/chitosan active films supplemented with Sonneratia ovata extract and Piper betel (L.) essential oil

In present work, the delivery kinetics of polyphenols from active films based on polyvinyl alcohol (PVOH) and chitosan (CS) enriched with Sonneratia ovata extract (SOE) and Piper betel (L.) essential oil (PBLO) in different food simulants were studied. SOE-added PVOH/CS films showed the slowest delivery rate and released amount of polyphenols. Co-supplementation with PBLO provided SOE-added PVOH/CS film with outstanding antioxidant property and thermo-stability. However, the swell and solubility properties of as-prepared films increased as PBLO concentration surged likely lying on the existence of oil droplets at internal and external surface, which affect to polyphenols delivery from active films in food simulants. The release rate of polyphenols of SOE and PBLO from as-prepared active films to several food simulants was evaluated by Peleg, Korsmeyer-Peppas, Kopcha model, and Fick's second law. The resulting parameters suggested that the release process was occurred due to the diffusion mechanism.

Effect of variable thickness on liquefied petroleum gas sensing response of ZnO thin films

In the present study, transparent and crack free ZnO thin films were casted on silicon substrate by using spin coating technique to analyze the effect of variable thickness. The crystallographic structure of as-prepared thin films were characterized using X-ray diffraction (XRD) technique and it was revealed that all the samples exhibit hexagonal wurtzite-type crystal symmetry with Surface morphology and granular microstructure illustrated uniform distribution and well-interlinking of grains and film thickness of ZnO@1, ZnO@2, and ZnO@3 samples was found to be 80 nm, 155 nm, and 230 nm, respectively. The effect of liquefied petroleum gas (LPG) purging on varying thickness of ZnO thin films were carried out lab customized gas calibrated testing apparatus. The maximum gas sensing response was observed for the sample ZnO@2 with thickness 155 nm at an operating temperature of 180 °C.

Tailoring of the Structural, Optical, and Electrical Characteristics of Sol-Gel-Derived Magnesium-Zinc-Oxide Wide-Bandgap Semiconductor Thin Films via Gallium Doping.

The Ga-doped Mg0.2Zn0.8O (GMZO) transparent semiconductor thin films were prepared using the sol-gel and spin-coating deposition technique. Changes in the microstructural features, optical parameters, and electrical characteristics of sol-gel-synthesized Mg0.2Zn0.8O (MZO) thin films affected by the amount of Ga dopants (0-5 at%) were studied. The results of grazing incidence X-ray diffraction (GIXRD) examination showed that all as-prepared MZO-based thin films had a wurtzite-type structure and hexagonal phase, and the incorporation of Ga ions into the MZO nanocrystals refined the microstructure and reduced the average crystallite size and flatness of surface roughness. Each glass/oxide thin film sample exhibited a higher average transmittance than 91.5% and a lower average reflectance than 9.1% in the visible range spectrum. Experimental results revealed that the optical bandgap energy of the GMZO thin films was slightly higher than that of the MZO thin film; the Urbach energy became wider with increasing Ga doping level. It was found that the 2 at% and 3 at% Ga-doped MZO thin films had better electrical properties than the undoped and 5 at% Ga-doped MZO thin films.

Determination of scattering and Urbach absorption contributions to the light extinction in PTFE films by using graphical representation technique and numerical solution of the inverse problem

Ellipsometrically obtained spectral dependences of ordinary αxy and extra-ordinary αz extinction/attenuation coefficients within the spectral range λ = 300…980 nm of uniaxially anisotropic polytetrafluoroethylene (PTFE) films were analyzed. We considered the capabilities and specific features of the graphical representation technique for determining the contribution of Rayleigh scattering and Urbach absorption to light attenuation in the spectral range beyond fundamental absorption. It has been shown that the graphical approach enables to estimate these contributions qualitatively, semi-quantitatively or quantitatively, depending on the situation. The conclusions made using the analysis of graphical representation are confirmed by numerical solution of the inverse problem via simulation of the αxy (λ), αz (λ) experimental dependences within the framework of a best-fit procedure. Being based on both of these approaches, we have ascertained that, in the as-prepared PTFE films, the so-called anomalous light scattering (ALS) with the spectral dependence of scattering coefficient αs ≈ as λ–p (p > 4) takes place. Transformation of scattering from ALS to the Rayleigh one with p ≈ 4 due to annealing is accompanied by an increase of Urbach (subband) absorption. Both of these factors cause narrowing the dynamic range of extinction coefficient values. Both scattering and absorption coefficients are higher for the component of light polarized along the normal to the substrate as compared to the component polarized in parallel to it. The relationship between observed behavior of the scattering and absorption coefficients and the film structure has been discussed.

Composition-dependent crystal structure, dielectric properties and temperature stability of the (1-x)CaZrO3-xSrTiO3 paraelectric thin films

The (1-x)CaZrO3-xSrTiO3 solid-solution thin films were prepared with different compositions from x = 0.05 to x = 0.45. The as-prepared thin films experienced such a crystal structure transition process from orthorhombic to pseudo cubic and then to cubic as the x increases. Among the as-prepared films, the smallest expansion ratio of lattice volume with temperatures, and the highest temperature stability of dielectric response and leakage current density at high voltage were found in the x = 0.3 thin films. The relationship between the tolerance factor and the temperature stability was analyzed from the crystal structure dependence of the absorbed thermal energy distribution. Finally, the x = 0.3 thin films were developed into thin-film capacitors, which showed high DC resistance and uniform capacitance properties. The result also shows that high temperature stability of the perovskite-type paraelectric thin films could be realized through the phase boundary design, and further improved by optimizing the temperature stability of the lattice structure.

Preparation and properties of a super-hydrophobic, electromagnetic interference shielding titanium nitride film

A super-hydrophobic, electromagnetic shielding titanium nitride (TiN) film was prepared using reactive magnetron sputtering by adjusting the sputtering power (30, 90, 180 and 250 W). The results showed that preferred orientation of the film had an obvious change with increasing sputtering power. At 30 W, too low sputtering power was not conducive to the crystallization of the film. At 90 W, TiN film grew toward [200] preferred orientation with a flat and compact surface, while the preferred orientation was [111] at 180 and 250 W with an uneven surface. Higher sputtering power could construct a low energy and high roughness surface which was helpful to improve the hydrophobic property. The water contact angle of the as-prepared TiN film at 250 W was 151.3°, indicating the achievement of super-hydrophobic property. Due to the decrease of electrical resistivity, the increase of film thickness and the special microstructure of pyramidal nanoparticles, the electromagnetic shielding effectiveness of TiN film at sputtering power of 250 W was about 40 dB, meaning that TiN film had good expect to be a super-hydrophobic, electromagnetic shielding material in the industrial field.

Furoic acid-mediated konjac glucomannan/flaxseed gum based green biodegradable antibacterial film for Shine-Muscat grape preservation

Considering the growing threats to the environment and human health, such as plastic pollution and food spoilage, the development of naturally antibacterial food packaging materials with biodegradable capabilities has recently attracted considerable attention. This work applies the concept of green environmental protection to packaging technology, and a new type of green edible antibacterial packaging film was developed. The basic idea is to incorporate furoic acid (FA), which possesses excellent antibacterial activity, into the flaxseed gum and konjac glucomannan matrix (FK) as a filler to obtain a series of FK-FA bioactive films. This incorporation simultaneously improves the hydrophobicity and UV-barrier ability by 12.28 % and 42.87 %, respectively. Meanwhile, the diameters of the antibacterial zone of the FK-FA0.4% films (composite FK films containing 0.4 % FA) against E. coli and S. aureus increased to 38.98 mm and 36.29 mm from 24.00 mm of pure FK film, respectively. As a consequence, the grape sample sealed with FK-FA0.4% film remained edible on the 18th day of storage, while those packaged with commercial PE film and pure FK were seriously rotted and lost edible value on the 12th day, further confirming the enhanced preservation capacity. Finally, the as-prepared films were established to be biodegradable and were almost completely degraded within 25 days under simulated environmental conditions. Overall, these promising results show the potential of FK-FA films for replacing plastic packaging materials as eco-friendly edible films with prolonged shelf life for active packaging.

A high thermal conductive composite phase change film for flexible solar/electro-thermal energy conversion

The applications of phase change materials (PCMs) in solar energy utilization, wearable thermal management and electro-thermal energy storage make it urgent to develop flexible PCMs with high thermal conductivity, electrical conductivity, morphological stability, and solar absorption capacity. Herein, we successfully fabricated a flexible multi-functional composite PCM film by adopting interwoven carbonized bamboo fibers (CBF) as the electrical and thermal conductive framework, with the introduction of polyvinylidene fluoride (PVDF) as the binder to enhance strength and flexibility and flexibility and paraffin as the thermal storage material. Besides, the introduction of Ti3C2Tx as a photon capturer and heating molecule further improved the solar-thermal conversion capability. The composite PCM films exhibited considerable flexibility, favorable thermal storage capacity (>103.6 J/g), and excellent long-term cycling stability. The interwoven electrical and thermal conductive skeleton endowed the flexible phase change films with satisfying electro-thermal conversion capacity and improving thermal conductivity, which further resulted in a promising solar-thermal conversion performance and remarkable Joule heating effect. The as-prepared flexible composite PCM films with excellent solar/electro-thermal conversion responses would be suitable smart materials for future wearable thermal management application.

Preparation and performance of PEN-OH@BNNS-OH/PEN interlayer dielectric films with superior interfacial compatibility

Polymer dielectric composites featuring great thermal stability, excellent mechanicals, and good dielectric properties have sparked considerable attention. Here, the preparation of hybrid filler was first performed. The hydroxyl end-capped polyarylene ether nitrile (PEN-OH) was synthesized and then hydroxy BNNS (BNNS-OH) was combined with PEN-OH to obtain PEN-OH@BNNS-OH, which is fabricated by ultrasonic combined with applying post-solid phase chemical reaction technology. The aim is to use the -OH interactions of BNNS-OH and PEN-OH to form hydrogen bonds that greatly enhance interfacial heat transport. Next, the post-solid phase chemical reaction is utilized to make PEN-OH crystallize, and its crystals located on the two-dimensional planes of BNNS-OH or between the layers can serve as a thermal bridge. Then, the as-prepared film with 10 wt% hybrid filler displays high thermal conductivity (1.17 W/m.K), 13.67%-fold higher than pure PEN film, boasts outstanding mechanical properties (stress 105 MPa, strain 6%), high glass transition temperature (Tg: 224 ℃), a dielectric constant (4.30 at 106 Hz), together with low dielectric loss (0.007 at 106 Hz). Besides, the film was post-treated to increase the thermal conductivity to 1.77 W/m.K, reach a higher Tg of 263 ℃, reduce the dielectric constant and loss to 3.68 and 0.006 at 106 Hz. Thus, it is suitable as a high-temperature-resistant dielectric material.

Optical Properties of Sputtered Iron Sulfide for Photonic Device Applications

Iron Pyrite is an earth-abundant, non-toxic, low-cost material commonly referred to as fool’s gold due to its golden-yellow appearance. It belongs to the family of transition metal dichalcogenides (TMDs) and gained fame as a potential solar material during the 70s and 80s. The reason was its suitable band gap and excellent absorption coefficient. However, the performance of pyrite never achieved a beneficial place among other materials and remained a mysterious path of research so far. With advanced technology and better characterization techniques and equipment available, the focus is again shifting towards exploring pyrite as a potential photovoltaic material which can compete with other materials, such as silicon, primarily in terms of cost. However, the true nature of pyrite and its application in photovoltaics cannot be adequately defined without looking deeply into its optical properties and interaction with light [1-3].Here in this work, we explored the photosensitivity of pyrite thin films at different thicknesses. These thin films were fabricated using an RF-powered sputtering method using a 99.9% FeS2 target. P-doped silicon and fused silica were used as substrates. The pressure and RF power were kept at 03 mTorrs and 70 watts, respectively, and the procedure took place at room temperature with an argon gas flow rate of ~24 cm3/min. The thickness was controlled by varying the sputtering time from 20 to 90 mins. As-prepared pyrite films were characterized through variable angle spectroscopic ellipsometry (VASE) and UV-vis spectrophotometer. An optical model was first developed for VASE in which the thin pyrite film showed light-absorbing characteristics (B-spline). Based on that model, the film thickness was determined. It was observed that the thickness of pyrite increased linearly with time, having grown to ~100 nm after 90 minutes of sputtering.UV-vis spectrophotometry was used to collect the transmission, reflectance and absorbance data for the films deposited onto a fused silica substrate. It was observed that the films showed very high absorbance in the UV range, and the absorbance tended to increase with the increase in thickness. The direct band gap was then calculated using absorbance data and building Tauc’s plot, which was observed to be around 2.25 eV.In conclusion, owing to its suitable properties and optical characteristics, iron pyrite opens many paths to scientists and researchers to explore its utilization not only in photovoltaics but also in other opto-electronic fields. However, further studies are also required to deeply understand its mechanism and capability. Nonetheless, high absorption of light in UV and visible range at very thin layers, suitable band gap and easy accessibility could be breakthrough parameters in near future for pyrite.

Solar Cell Application of 1D Heterostructure Based on Single-Walled CNT

The experimental synthesis of one-dimensional (1D) van der Waals heterostructures, first introduced in 2020 [1], has attracted much research attention. Discussions upon this coaxial stack of different atomic layers are not only limited to synthesis and characteristics, but also extended to applications. Many unique properties of the 1D van der Waals heterostructures, such as the adjustable band gap, strong quenching of photoluminescence of MoS2 by inner single-walled CNT, enable this structure to be a potential active layer material for solar cells [2].For the synthesis of 1D van der Waals heterostructures, we first use dispersed high-purity semiconducting single-walled carbon nanotubes (s-SWCNT) solution obtained from Kataura group [3] as inner tube material. With an anodic aluminum oxide (AAO) membrane filter and HCl, we managed to fabricate a free-standing s-SWCNT film [4]. Then following our established CVD process [5], we are wrapping this inner s-SWCNT tube with an insulating boron nitride layer, and a semiconducting MoS2 layer. After that, the as-prepared 1D van der Waals heterostructures film will be utilized for solar cell fabrication.The solar cell is adopting an n-i-p structure, in the order of glass-ITO-SnO2-Active layer-Spiro-Au. After spin-coating and annealing SnO2 (electron transporting layer) onto ITO-patterned glass, the 1D van der Waals heterostructure film is laminated on the SnO2 layer. Spiro (hole transporting layer) will be then spin-coated onto the film. Finally, gold is vapor-deposited onto the device in a vacuum chamber, as the top electrode [6].Through photocurrent measurement of 1D van der Waals structure film using Esko film, a mixture of metallic-SWCNT and s-SWCNT, we found it is photosensitive with exposure to light and laser. The 1D van der Waals structure film using high-purity s-SWCNT is then expected to generate higher photocurrent, the experimental result will be updated in the future. By the IV measurement of the solar cell, we observed the photovoltaic effect of the device. Moreover, this new conceptual solar cell is believed to possess many advantages at the same time, such as flexibility, durability, non-toxicity, and sustainability [2]. However, further research on the choices of materials and optimizations of device parameters is still required in order to reach sufficient power conversion efficiency as a photovoltaic device.[1] R. Xiang et al., Science 367, 537–542 (2020)[2] R. Xiang et al., Natl Sci Open 1, 3 (2022)[3] J. Cui et al., ACS Appl. Nano Mater 2, 1, 343–350 (2019)[4] C. Zhang et al., ACS Nano 16, 11, 18630–18636 (2022)[5] M. Liu et al., ACS Nano 15, 5, 8418–8426 (2021)[6] J.-M. Choi et al, Adv. Funct. Mater. 32, 2204594 (2022)