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Transition metal dichalcogenide (TMDC) materials are attractive candidates for 2D solar cell devices thanks to their straightforward integration with various substrates and traditional semiconductor technologies, wide band gap ranges over the visible light spectrum, and high absorption coefficient values. Although there are several previous reports on the fabrication of 2D material-based solar cells, difficult and complex processes in the fabrication are highly required to be modified for wider use in daily life applications. Photolithography, the most commonly used manufacturing process for TMDC-based solar cells, is complicated. In this study, we demonstrate that the fabrication of 2D tungsten diselenide (WSe2) by adopting a wet transfer process with thermal release tape simplifies the manufacturing steps for TMDC-based solar cell devices. This simplification not only reduces the production cost by excluding several factors such as transmittance, thermal expansion, surface flatness, and durability but also improves the yield. Furthermore, a proof-of-concept demonstration of creating a WSe2/Si junction with an aluminum oxide (Al2O3) antireflective coating provided a power conversion efficiency of 6.39%, which is a significant improvement over that of a WSe2/Si solar cell without the antireflective coating layer (1.08%).

Tomato is an essential vegetable in the world due to its nutritional importance. It has vitamin A C and lycopene, which reduce the prostate cancer, and heart and age-related diseases. Tomato wilt disease (TWD) is a potential threat and spreading rapidly in tomato fields in Pakistan. The survey on the disease prevalence of Fusarium wilt (Fusarium oxysporum f.sp. lycopersici (Fol)) of tomato was conducted in the major tomato growing areas of Punjab, viz., Hafizabad, Pakpattan, Khushab, Sargodha and Faisalabad districts during the cropping season 2018. Tomato wilt disease incidence was higher in district Sargodha (94%) followed by Faisalabad (92%) and Khushab (65%). Two districts, Pakpattan and Hafizabad showed 86% and 73% incidence, respectively. The survey revealed that tomato disease incidence was prevalent with varying intensities in all surveyed districts of Punjab. Moreover, the variation in disease prevalence of tomato wilt disease in different locations was due to the environmental conditions of that area and the varieties being cultivated.

Drosicha mangiferae (Green) (Homoptera: Margarodidae) is sucking, polyphagous, highly fecund and destructive insect pest of mango, citrus, guava, and plum java. Control of this pest in citrus orchards is dependent upon use of insecticide from several groups which might reduce the efficacy of several chemicals. In this study, we have generated the baseline toxicity data of ten formulated insecticides viz., deltamethrin, bifenthrin, fenpropathrin, methidathion, chlorpyrifos, acetamiprid, imidacloprid, thiamethoxam, spirotetramat, and flonicamid against adult females of D. mangiferae by conducting leaf-dip bioassays in the laboratory, over the period of consecutive three years from 2017–2019 in order to assess the susceptibility status of field collected populations from citrus orchard of Sargodha, Punjab, Pakistan. Results showed that bifenthrin, thiamethoxam, spirotetramat and flonicamid exhibited higher toxicities to D. mangiferae adult females owing to very low LC50 values. Significantly larger LC50 values were obtained for all other insecticides such as deltamethrin, fenpropathrin, methidathion, chlorpyrifos, acetamiprid, and imidacloprid which indicated that these insecticides showed comparatively lower toxicities. It can be concluded that insecticides with very low LC50 values should be incorporated in the management program of D. mangiferae to increase control efficiency and minimize the resistance development.

To implement artificial neural networks (ANNs) based on memristor devices, it is essential to secure the linearity and symmetry in weight update characteristics of the memristor, and reliability in the cycle-to-cycle and device-to-device variations. This study experimentally demonstrated and compared the filamentary and interface-type resistive switching (RS) behaviors of tantalum oxide (Ta

An ultrahigh capacity supercapacitor is fabricated using a nano-layered MXene as an active electrode material, and Ni-foil is used as a current collector. The high-quality Ti3C2Tx obtained from supernatant during etching and washing processes improves the specific capacitance significantly. As another strategy, the surface of Ni-foil is engineered by coating chemical vapor deposition-grown graphene. The graphene grown directly on the Ni-foil is used as a current collector, forming the electrode structure of Ti3C2Tx/graphene/Ni. The surface passivation of the current collectors has a high impact on charge-transfer, which in turn increases the capacitance of the supercapacitors. It is found that the capacitance of the graphene-based supercapacitors is more than 1.5 times of the capacitance without graphene. A high specific capacitance, ~ 542 F/g, is achieved at 5 mV/s scan rate based on cyclic voltammetry analysis. Also, the graphene-based supercapacitor exhibits a quasi-rectangular form in cyclic voltammetry curves and a symmetric behavior in charge/discharge curves. Furthermore, cyclic stability up to 5000 cycles is confirmed with high capacitance retention at high scan rate 1000 mV/s. A reduced series resistance with a high limit capacitance is revealed by equivalent circuit analysis with the Nyquist plot.

The present study pioneered an oxygen migration-driven metal to insulator transition Mott memory, a new type of nonvolatile memory using lanthanum titanium oxide (LTO). We first show the reset first bipolar property without an initial electroforming process in LTO. We used oxygen-deficient ZnO as an interlayer between LTO and a W electrode to clarify whether oxygen migration activates LTO as the Mott transition. ZnO oxygen deficiency provides oxygen ion migration paths as well as a reservoir, facilitating oxygen migration from LTO to the W electrode. Thus, including the ZnO interlayer improved oxygen migration between LTO and the W electrode, achieving a 10-fold increased on/off current ratio. The current research contributes to a better understanding of valence change Mott memory by exploring the LTO resistive switching mechanism and ZnO interlayer influences on the oxygen migration process.

We demonstrate a solar cell application based on vertical graphene nano hills (VGNH) directly grown without using a catalyst. The photovoltaic device based on VGNH grown on top of interfacial layer Al2O3 is compared with that on top of bare silicon by critically analyzing its electrical properties. The role of the interfacial layer is to minimize surface recombination and enhance its built-in potential. Our key process is simple to fabricate large-area devices, avoiding an unreliable transfer process. In addition, the thickness of VGNH is optimized and the surface texturing of silicon is performed to overcome the crucial problem of the high reflectivity of silicon. A low reflectivity of thick layers of VGNH is achieved with low series resistance despite of the vertical structure, which is beneficial for high photocurrent. A higher work function of VGNH ∼4.7 eV is measured by KPFM. The conversion efficiency of 10.97% is achieved with an active area of 0.9 cm2 by co-doping with PEDOT: PSS and inorganic acid HNO3. Moreover, the photo-responsivity of the VGNH-based device is estimated as 1.196 AW-1 under deep ultraviolet light.

Two-dimensional (2D) layered materials have an atomically thin and flat nature which makes it an ultimate candidate for spintronic devices. The spin-valve junctions (SVJs), composed of 2D materials, have been recognized as unique features of spin transport polarization. However, the magnetotransport properties of SVJs are highly influenced by the type of intervening layer (spacer) inserted between the ferromagnetic materials (FMs). In this situation, the spin filtering effect at the interfaces plays a critical role in the observation of the magnetoresistance (MR) of such magnetic structures, which can be improved by using promising hybrid structure. Here, we report MR of bilayer graphene (BLG), single-layer MoSe2 (SL-MoSe2), and BLG/SL-MoSe2 heterostack SVJs. However, before annealing, BLG and SL-MoSe2 SVJs demonstrate positive MR, but after annealing, BLG reverses its polarity while the SL-MoSe2 maintains its polarity and demonstrated stable positive spin polarizations at both interfaces due to meager doping effect of ferromagnetic (FM) contacts. Further, Co/BLG/SL-MoSe2/NiFe determines positive MR, i.e., ~ 1.71% and ~ 1.86% at T = 4 K before and after annealing, respectively. On the contrary, NiFe/BLG/SL-MoSe2/Co SVJs showed positive MR before annealing and subsequently reversed its MR sign after annealing due to the proximity-induced effect of metals doping with graphene. The obtained results can be useful to comprehend the origin of polarity and the selection of non-magnetic material (spacer) for magnetotransport properties. Thus, this study established a new paragon for novel spintronic applications.

We have developed a novel way to fabricate few layers graphene by controlling the uniformity of graphene using ‘tape-peeling’ method to solve the problem in the direct growth method based on the polymer carbon source. This method increases uniformity of the directly grown graphene by removing large amounts of residues during graphene direct growth using tape-peeling, and it can help in controlling the thickness of graphene. For the direct growth of graphene, nickel (Ni) was deposited on the silicon dioxide (SiO2) substrate, and poly (methylmethacrylate) was used as a carbon source. During the annealing process in the chemical vapor deposition (CVD) technique, a few layer graphene is grown between the Ni and the SiO2 substrate. The Ni is removed by etching using iron (III) chloride (FeCl3), but thick carbon residues are left on the substrate. These residues are removed, and the overall thickness of graphene, to some extent, is controlled by the tape-peeling method. It has been found that the tape-peeling method is effective in removing the residues on the sample surface. The directly grown graphene processed by tape-peeling was used in fabricating the photoelectric devices and the corresponding studies have been performed.

Vertical integration of two dimensional (2D) layered materials is indispensable in making van der Waals (vdWs) heterostructures for promising electronic and optoelectronic devices. Herein, we report excellent electrical and photoelectrical measurements where the current ON & OFF ratio of FET is increased by decreasing the temperature in the graphene/ReSe2/graphene heterojunction. We investigated the photoresponsivity in broad spectral range (UV-Vis-NIR) and achieved high photoresponsivity of 1.5 × 107 A W−1 and external quantum efficiency of ∼64% at λ = 220 nm. Further, the photovoltaic effect was examined, which significantly modulated the short circuit current (Isc) from 4.2 × 10−8 A to 2.6 × 10−7 A and open-circuit voltage (Voc) from 0.21 V to 0.44 V at different wavelengths (1064, 840, 514 and 220 nm), attributed to the photo-generation and recombination rate of the carriers. Moreover, photoresponsivity was observed near 1.2 × 106, 8.6 × 106 and 1.5 × 107 A W−1 by applying different gate biases (0, 20 and 40 V), respectively. Further, we have explored the photocurrent and photoresponsivity at different intensities of incident light (200, 260, 400, 620 and 850 μW cm−2). In addition, we calculated the rise and decay response times of photodetectors at different wavelengths and power densities, which depend upon the trap sites in the energy band of ReSe2. These devices opened up new ways to improve the performance of photodetectors from the UV to the NIR region.

The effect of Ti3C2Tx MXene etched at different temperatures (25 °C, 50 °C, and 80 °C) on the capacitance of supercapacitors without the use of conducting carbon-black or a binder was studied. The MXene etched using concentrated HCl acid (12 M)/LiF was used as an active electrode and Ni-foil as a current collector. It was observed that the elevated etching temperature facilitates the etching of the MAX phase and the exfoliation of MXene layers. However, this led to the formation of additional functional groups at the MXene surface as the temperature was increased to 80 °C. The specific capacitance of Ti3C2Tx-based supercapacitors increased from 581 F g−1 for MXene etched at 25 °C to 657 F g−1 for those etched at 50 °C at the scan rate of 2 mV s−1. However, the specific capacitance reduced to 421 F g−1 as the etching temperature was increased to 80 °C at the same scan rate. The supercapacitors based on MXenes etched at the intermediate temperature (50 °C) exhibited higher specific capacitance in a wide range of scan rate, symmetry in charge/discharge curves, high cyclic stability at a scan rate of 1000 mV s−1 for up to 3000 cycles. The electrochemical impedance spectroscopy studies indicated low series resistance, reduced charge-transfer resistance, and decreased Warburg impedance for the supercapacitor based on the MXene etched at the intermediate temperature.

Metal–organic frameworks (MOFs) serve as expedient self-templated precursors to derive hybrid materials with various functionalities. This study develops a bimetallic MOF-derived approach for the facile synthesis of nitrogen-doped carbon integrated nickel–cobalt mixed metal phosphide (NiCoP/NC) using a controlled experimental procedure for supercapacitors. Here, the nitrogen-doped carbon nanosheet functions as a conductive framework and protective layer for NiCoP nanostructures and offers facile pathways for easy charge transfer, abundant surface active sites and improves the stability of the electrode. The marigold flower-like morphology of NiCoP nanostructures stores a large number of ions in their petals and shortens the ion diffusion length. The electrochemical analysis demonstrates that the as-designed NiCoP/NC electrode possesses a high specific capacity of 690.6 mA h g−1 (6.22 F cm−2) at 1 A g−1, high rate capability and excellent cycling stability. Additionally, a hybrid supercapacitor built with NiCoP/NC and activated carbon as positive and negative electrodes shows a maximum specific energy of 47 W h kg−1 at a specific power of 1666 W kg−1 and good capacity retention over 10 000 charge–discharge cycles. The present multicomponent approach combines the virtues of efficient redox chemistries of each element and N-doped carbon providing abundant surface active sites while stabilizing the active electrode material during repeated cycling.

openaire: EC/H2020/834742/EU//ATOP Two-dimensional (2D) transition metal dichalcogenides have attracted vibrant interest for future solid-state device applications due to their unique properties. However, it is challenging to realize 2D material based high performance complementary devices due to the stubborn Fermi level pinning effect and the lack of facile doping techniques. In this paper, we reported a hybrid Gr/Ni contact to WS2, which can switch carrier types from n-type to p-type in WS2. The unorthodox polarity transition is attributed to the natural p-doping of graphene with Ni adsorption and the alleviation of Fermi level pinning in WS2. Furthermore, we realized asymmetric Ni and Gr/Ni hybrid contacts to a multilayer WS2 device, and we observed synergistic p-n diode characteristics with excellent current rectification exceeding 104, and a near unity ideality factor of 1.1 (1.6) at a temperature of 4.5 K (300 K). Lastly, our WS2 p-n device exhibits high performance photovoltaic ability with a maximum photoresponsivity of 4 × 104 A W-1 at 532 nm wavelength, that is 108 times higher than that of graphene and 50 times better than that of the monolayer MoS2 photodetector. This doping-free carrier type modulation technique will pave the way to realize high performance complementary electronics and optoelectronic devices based on 2D materials.

Polymer-dispersed liquid crystals (PDLCs) exhibiting transmittance switching are utilized for preserving energy and protecting privacy. Here we prepared a typical PDLC mixture from a commercially available polymer and liquid crystal with nano-beads. A wire-bar coater was used to coat the PDLC mixture on indium-tin-oxide-coated glass, and a PDLC cell was assembled by coupling another glass in a vacuum, instead of a polymer film. Uniform glass-based PDLCs were fabricated successfully with an area of 15 × 15 cm2, while an injection process with capillary action was not available for this large-scale device fabrication. The switching behavior of the cells was characterized by ramping the AC voltage, and a transmittance change of ∼70% was measured. In a typical roll-to-roll process, only flexible polymer films have been used in lamination, in which deterioration in transparency occurs over the course of time, reducing the efficiency. In this study, to improve the optical properties, PDLC switchable glazing is fabricated directly onto glass substrates instead of onto plastic polymers. This PDLC switchable glazing, exhibiting low haziness and wide-angle vision, can be fabricated at a large scale by a vacuum-coupling process, with potential use as glass windows for energy-efficient buildings.

Tomato is very significant and full of nutrition vegetable crop. It is enriched with vitamin a and C, lycopene, and protects from prostate cancer, cardiovascular diseases. Tomato wilt disease (TWD) caused by F. oxysporum f.sp. lycopersici (Fol) is a serious threat to tomato crop in Pakistan and spreading to those areas in which it was not previously present. The current research was planned to evaluate the fungi-toxic activity of fungicides against F. oxysporum in vitro and under greenhouse conditions. Four fungicides which include Carbendazim, Benomyl, Curzate and Nativo, at 500ppm, 750ppm and 1000ppm concentrations, were evaluated using food poison technique. The overall results showed that all fungicides significantly (P < 0.05) inhibited mycelial growth of F. oxysporum, however, Nativo proved to be best followed by Carbendazim, Benomyl at all concentrations. The reduction in colony growth of pathogen gradually increased by increasing the fungicide concentration. Two fungicides, Nativo and Carbendazim and their concentrations 750 and 1000 ppm, which proved to be effective in laboratory conditions, also evaluated under greenhouse conditions. Both fungicides effectively controlled TWD under greenhouse conditions. The present research revealed that Nativo and Carbendazim at 750 and 1000 ppm concentrations are effective against Fol, thus may be included in management strategy of TWD.

It is of immense interest to improve the power conversion efficiency of graphene/silicon Schottky junction solar cells. The ultrathin graphene has essential properties, such as tunable work function to increase Schottky barrier height and built-in potential for efficient charge transport in photovoltaic devices. Here, we use plasma-enhanced CVD to grow graphene directly on planar n-type silicon to fabricate solar cells compatible for industrial-level applications. A key component to our accomplishment is the optimization of directly grown, continuous layers of graphene to achieve superior performance. Thus, by controlling the graphene thickness, the work function is significantly improved, the open circuit voltage is increased, and the energy conversion efficiency is enhanced. While the transfer of CVD grown graphene has limitations due to cracks and impurities during the complex process, our direct growth method demonstrates an efficiency of 5.51 % on bare planar silicon with a large device area. Furthermore, the efficiency is remarkably increased to 9.18 % by adding and doping a polymer layer. Interestingly, with the addition of a doped polymer layer, the cell exhibits excellent stability for at least one month. Our result suggests a promising simple path to fabricate high efficiency solar cells at low temperature and low cost.

Three-dimensional (3D) imaging of nanostructures with high aspect ratio features is a challenging problem of broad relevance to nanoscience and nanotechnology. Though a wide variety of experimental strategies to improve 3D imaging capabilities have been proposed, current measurement capabilities are mainly limited to imaging deep trenches, in large part due to the lack of truly 3D scanning algorithms and limited dynamic control of the tilt angle. Herein, we report a non-contact atomic force microscope (AFM) strategy that overcomes these challenges by employing an intelligent 3D scanning algorithm that combines sidewall detection and real-time adjustment of the probe’s direction. To test this approach, we measured the depth and sidewall topography of porous anodic aluminum oxide (trench), via holes and silicon nanopillar (protrusion) with precision tracing. Using a carbon nanotube-based AFM probe, it was possible to measure the depth of holes with an aspect ratio of 5.9. In addition to this, we have successfully achieved the 3D image of via holes with an aspect ratio of 4.3 and a resolution of 2 nm, which enables realistic profiling of the sidewall and bottom edge of holes. Taken together, our findings demonstrate how the intelligent scanning algorithm based on detection-and-decision with a high-aspect-ratio probe can be utilized as a broadly applicable nanoscience measurement tool to characterize 3D topographical features of nanostructures.

Lattice matching has been supposed to play an important role in the coupling between two materials in a vertical heterostructure (HS). To investigate this role, we fabricated a heterojunction device with a few layers of p-type WSe2 and n-type MoSe2 with different crystal orientation angles. The crystal orientations of WSe2 and MoSe2 were estimated using high-resolution X-ray diffraction. Heterojunction devices were fabricated with twist angles of 0, 15, and 30°. The I–V curve of the sample with the twist angle of 0° under the dark condition showed a diodelike behavior. The strong coupling due to lattice matching caused a well-established p–n junction. In cases of 15 and 30° samples, the van der Waals gap was built because of lattice mismatching, which resulted in the formation of a potential barrier. However, when the light-emitting diode light of 365 nm (3.4 eV) was illuminated, it was possible for excited electrons and holes to jump beyond the potential barrier and the current flowed well in both forwar...

In graphene/silicon (Gr/Si) solar cell antireflection (ARCs) coatings remarkably enhance the power conversion efficiency. Traditionally titanium dioxide and polymethyl methacrylate used an ARC in Gr/Si solar cells. In such cases controlling film thicknesses and smoothness required a lot of efforts. Here we introduced Vanadium Pentoxide (V2O5) as an ARC in Gr/Si solar cells deposited using thermal evaporator. A well smooth controlled thin-film of V2O5 was achieved. It can easily be thermal evaporated because of its low melting temperature. It was observed after V2O5 coating current density of Gr/Si solar cell remarkably increased from 14 mA/cm2 to 28 mA/cm2 without losing the fill factor. It also helps to improve the Voc from 0.41 to 0.44 V. Different layer thickness shows different colors, results show that a 70 nm layer thickness of V2O5 shows the best ARC for single layer Gr/Si solar cell.

Three-dimensional integration and stacking of semiconductor devices with high density, its compactness, miniaturization and vertical 3D stacking of nanoscale devices highlighted many challenging problems in the 3D parameter’s such as CD (critical dimension) measurement, depth measurement of via holes, internal morphology of through silicon via (TSV), etc. Current challenge in the high-density 3D semiconductor devices is to measure the depth of through silicon via (TSV) without destructing the sample; TSVs are used in 3D stacking devices to connect the wafers stacked vertically to reduce the wiring delay, power dissipation, and of course, the form factor in the integration system. Special probes and algorithms have been designed to measure 3D parameters like wall roughness, sidewall angle, but these are only limited to deep trench-like structures and cannot be applied to structures like via holes and protrusions. To address these problems, we have proposed an algorithm based nondestructive 3D Atomic Force Microscopy (AFM). Using the high aspect ratio (5, 10, 20, 25) multiwall carbon nanotubes (MWCNTs) AFM probe, the depth of holes up to 1 micron is faithfully obtained. In addition to this, internal topography, side walls, and location of via holes are obtained faithfully. This atomic force microscopy technique enables to 3D scan the features (of any shape) present above and below the surface.

Over the past decade, graphene-based solar cells have received increasing exploration. In particular, the metal–insulator–semiconductor (MIS)-type solar cells have an inherent cost advantage compared to the p-n junction solar cells. However, the technological progress in graphene solar cells based on the MIS junction is currently facing a number of serious challenges, including long-term stability, surface recombination at the interface level, and surface defects. To overcome these barriers, a simple, cost-effective method is developed herein for the interfacial single-component passivation of Al2O3 with NH3 or H2O2, and co-passivation with NH3 and H2O2 together. The interfacial layer between the silicon and the directly-grown graphene operates as an effective electron blocking layer, thus leading to the minimization of surface recombination. Further, the NH3-H2O2 co-passivated Al2O3 performs the dual role of providing a good platform for the growth of graphene and enhancing the performance of the fabricated solar cell. Moreover, in a proof of concept demonstration, the fabricated graphene-silicon (Gr/Si) Schottky junction with an NH3-H2O2 co-passivated Al2O3 interfacial layer exhibits an efficiency of 9.49%, which is a major enhancement over that of the Gr/Si solar cell without an interfacial layer (i.e., 3.19%). These results demonstrate that the control of oxygen-related defects containing non-lattice oxygen in the Al2O3 interfacial layer remarkably impacts the charge transfer resistance and electron recombination processes. This work can be viewed as an elegant interface engineering approach to the co-passivation of Al2O3 for optoelectronic applications.

Two-dimensional (2D) transition metal dichalcogenides have attracted vibrant interest for future solid-state device applications due to their unique properties. However, it is challenging to realize 2D material based high performance complementary devices due to the stubborn Fermi level pinning effect and the lack of facile doping techniques. In this paper, we reported a hybrid Gr/Ni contact to WS2, which can switch carrier types from n-type to p-type in WS2. The unorthodox polarity transition is attributed to the natural p-doping of graphene with Ni adsorption and the alleviation of Fermi level pinning in WS2. Furthermore, we realized asymmetric Ni and Gr/Ni hybrid contacts to a multilayer WS2 device, and we observed synergistic p-n diode characteristics with excellent current rectification exceeding 104, and a near unity ideality factor of 1.1 (1.6) at a temperature of 4.5 K (300 K). Lastly, our WS2 p-n device exhibits high performance photovoltaic ability with a maximum photoresponsivity of 4 × 104 A W-1 at 532 nm wavelength, that is 108 times higher than that of graphene and 50 times better than that of the monolayer MoS2 photodetector. This doping-free carrier type modulation technique will pave the way to realize high performance complementary electronics and optoelectronic devices based on 2D materials.

Vertical integration of two dimensional (2D) layered materials is indispensable in making van der Waals (vdWs) heterostructures for promising electronic and optoelectronic devices. Herein, we report excellent electrical and photoelectrical measurements where the current ONOFF ratio of FET is increased by decreasing the temperature in the graphene/ReSe

Polymer-dispersed liquid crystals (PDLCs) exhibiting transmittance switching are utilized for preserving energy and protecting privacy. Here we prepared a typical PDLC mixture from a commercially available polymer and liquid crystal with nano-beads. A wire-bar coater was used to coat the PDLC mixture on indium-tin-oxide-coated glass, and a PDLC cell was assembled by coupling another glass in a vacuum, instead of a polymer film. Uniform glass-based PDLCs were fabricated successfully with an area of 15 × 15 cm

The effect of Ti

An ultrahigh capacity supercapacitor is fabricated using a nano-layered MXene as an active electrode material, and Ni-foil is used as a current collector. The high-quality Ti3C2Tx obtained from supernatant during etching and washing processes improves the specific capacitance significantly. As another strategy, the surface of Ni-foil is engineered by coating chemical vapor deposition-grown graphene. The graphene grown directly on the Ni-foil is used as a current collector, forming the electrode structure of Ti3C2Tx/graphene/Ni. The surface passivation of the current collectors has a high impact on charge-transfer, which in turn increases the capacitance of the supercapacitors. It is found that the capacitance of the graphene-based supercapacitors is more than 1.5 times of the capacitance without graphene. A high specific capacitance, ~ 542 F/g, is achieved at 5 mV/s scan rate based on cyclic voltammetry analysis. Also, the graphene-based supercapacitor exhibits a quasi-rectangular form in cyclic voltammetry curves and a symmetric behavior in charge/discharge curves. Furthermore, cyclic stability up to 5000 cycles is confirmed with high capacitance retention at high scan rate 1000 mV/s. A reduced series resistance with a high limit capacitance is revealed by equivalent circuit analysis with the Nyquist plot.

As one of the newly discovered transition-metal dichalcogenides (TMDs), rhenium disulfide (ReS2) has been investigated mostly because of its unique characteristics such as the direct band gap nature even in bulk form, which is not prominent in other TMDs (e.g., MoS2, WSe2, etc.). However, this material possesses a low mobility and an on/off ratio, which restrict its usage in high-speed and fast switching applications. Low mobilities or on/off ratios can also be caused by substrate scattering as well as environmental effects. In this study, we used few-layer ReS2 (FL-ReS2) as a channel material to investigate the substrate-dependent mobility, current on/off ratio, Schottky barrier height (SBH), and trap density of states of different dielectric substrates. The hexagonal boron nitride (h-BN)/FL-ReS2/h-BN structure was observed to exhibit a high mobility of 45 cm2 V–1 s–1, current on/off ratio of about 107, the lowest SBH of about 12 mV at a zero back-gate voltage (Vbg), and a low trap density of states of a...

Graphene/Si Schottky junction solar cells are widely studied in relation to the harvesting of solar energy, but high efficiency is limited due to surface recombination at the interface. Moreover, surface defects, wrinkles, and impurities may arise during the wet transfer process of graphene. We propose an easy approach to fabricate high efficiency solar cells by using directly grown graphene on a textured substrate with a large active area. In our novel technique, we directly grow a few layers of graphene on top of Al2O3/Si by using plasma enhanced chemical vapor deposition. The high-k dielectric layer of Al2O3 acts as an electron blocking layer which minimizes the surface recombination at the interface. Furthermore, the barrier width is optimized by controlling the thickness of the Al2O3 interlayer to achieve the highest efficiency of 8.4%. The devices were not intentionally doped, and no aging effect was found in 9 months. We believe that our stable solar cell results indicate a new route for the production of metal-insulator-semiconductor Schottky junction solar cells with high efficiency without need of chemical doping of the emitter layer.