Exploring the Potential of Nitrogen-Doped Graphene in ZnSe-TiO2 Composite Materials for Supercapacitor Electrode.

The current study explores the prospective of a nitrogen-doped graphene (NG) incorporated into ZnSe-TiO2 composites via hydrothermal method for supercapacitor electrodes. Structural, morphological, and electronic characterizations are conducted using XRD, SEM, Raman, and UV analyses. The electrochemical study is performed and galvanostatic charge-discharge (GCD) and cyclic voltammetry (CV) are evaluated for the supercapacitor electrode material. Results demonstrate improved performance in the ZnSe-NG-TiO2 composite, indicating its potential for advanced supercapacitors with enhanced efficiency, stability, and power density. Specific capacity calculations and galvanic charge-discharge experiments confirmed the promising electrochemical activity of ZnSe-NG-TiO2, which has a specific capacity of 222 C/g. The negative link among specific capacity and current density demonstrated the composite's potential for high energy density and high-power density electrochemical devices. Overall, the study shows that composite materials derived from multiple families can synergistically improve electrode characteristics for advanced energy storage applications.

Synergistic CuCoS-PANI materials for binder-free electrodes in asymmetric supercapacitors and oxygen evolution.

In advanced electronics, supercapacitors (SCs) have received a lot of attention. Nevertheless, it has been shown that different electrode designs that are based on metal sulfides are prone to oxidation, instability, and poor conductance, which severely limits their practical application. We present a very stable, free-standing copper-cobalt sulfide doped with polyaniline as an electrode coated on nickel foam (CuCoS/PANI). The lightweight nickel foam encourages current collection as well as serving as a flexible support. The CuCoS-PANI electrode had a substantially greater 1659 C g-1 capacity at 1.0 A g-1. The asymmetric supercapacitor (ASC) can provide an impressive 54 W h kg-1 energy density while maintaining 1150 W kg-1 power. Additionally, when employed as an electrocatalyst in the oxygen evolution reaction, CuCoS/PANI exhibited a 200 mV overpotential and 55 mV dec-1 Tafel slope, demonstrating its effectiveness in facilitating the reaction.

Pyridine 3,5-dicarboxylate-based metal-organic frameworks as an active electrode material for battery-supercapacitor hybrid energy storage devices.

Efficient energy storage and conversion is crucial for a sustainable society. Battery-supercapacitor hybrid energy storage devices offer a promising solution, bridging the gap between traditional batteries and supercapacitors. In this regard, metal-organic frameworks (MOFs) have emerged as the most versatile functional compounds owing to their captivating structural features, unique properties, and extensive diversity of applications in energy storage. MOF properties are governed by the structure and topological characteristics, which are influenced by the types of ligands and metal nodes. Herein, MOFs based on pyridine 3,5-dicarboxylate (PYDC) ligand in combination with copper and cobalt are electrochemically analyzed. Owing to the promising initial characterization of Cu-PYDC-MOF, a battery supercapacitor hybrid device was fabricated, comprising Cu-PYDC-MOF and activated carbon (AC) electrodes. The device showcased energy and power density of 17 W h kg -1 and 2550 W kg -1, respectively. Dunn's model was employed to gain deeper insights into the capacitive and diffusive contributions of the device. With their performance and versatility, the PYDC-based MOFs stand at the forefront of energy technology, ready to power a brighter future for upcoming generations.

Improvement of the Self-Controlled Hyperthermia Applications by Varying Gadolinium Doping in Lanthanum Strontium Manganite Nanoparticles.

In this study, silica-encapsulated gadolinium was doped in lanthanum strontium manganite nanoparticles (NPs) with different concentrations using the citrate-gel auto-combustion method. We focused on tuning the Curie temperature and enhancing the specific absorption rate (SAR) of silica-coated gadolinium-doped lanthanum strontium manganite NPs to make them suitable for self-controlled magnetic hyperthermia. The samples were characterized by using transmission electron microscopy (TEM), X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and magnetic measurements to examine the structural, optical, and magnetic properties of the manganite NPs. While our results exhibit a successful doping of gadolinium in lanthanum strontium manganite NPs, we further prepared magnetic core NPs with sizes between 20 and 50 nm. The Curie temperature of the NPs declined with increasing gadolinium doping, making them promising materials for hyperthermia applications. The Curie temperature was measured using the magnetization (M-T) curve. Magnetic heating was carried out in an external applied AC magnetic field. Our present work proved the availability of regulating the Curie temperature of gadolinium-doped lanthanum strontium manganite NPs, which makes them promising candidates for self-controlled magnetic hyperthermia applications.

Analyzing synthesis routes for BaCuPO4: implications for hydrogen evolution and supercapattery performance.

In recent years, energy storage and conversion tools have evolved significantly in response to rising energy demands. Owing to their large surface area, superior electric and chemical stabilities, and thermal conductivities, barium copper phosphate (BaCuPO4) materials are promising electrode materials for electrochemical energy storage systems. In this study, the synthesis of nanostructures (NSs) using hydrothermal and chemical precipitation methods and exploring the electrochemical characteristics of BaCuPO4 in asymmetric supercapacitors provides a comparative investigation. Systematic characterization shows that nanomaterials prepared by applying the hydrothermal method have a more crystalline and large surface area than chemical precipitation. In the three cell arrangements, the hydrothermally prepared BaCuPO4 NSs delivered a high specific capacity (764.4 C g-1) compared to the chemical precipitation route (660 C g-1). Additionally, the supercapattery associated with the two electrode assemblages delivers an optimum specific capacity of 77 C g-1. The energy and power density of BaCuPO4//AC NSs were 52.13 W h kg-1 and 950 W kg-1, respectively. A durability test was also performed with BaCuPO4//AC NSs for 5000 consecutive cycles. Further, the coulombic efficiency and capacity retention of BaCuPO4//AC after 5000 cycles were 81% and 92%, respectively. Bimetallic phosphate is comparatively suggested for future perspectives towards HER to overcome the performance of single metal phosphate materials. This is the first approach, we are aware of, for investigating the electrochemical behavior of BaCuPO4, and our results suggest that it may be useful as an electrode material in electrochemical systems requiring high energy and rate capabilities.

Synergistic redox enhancement: silver phosphate augmentation for optimizing magnesium copper phosphate in efficient energy storage devices and oxygen evolution reaction.

The implementation of battery-like electrode materials with complicated hollow structures, large surface areas, and excellent redox properties is an attractive strategy to improve the performance of hybrid supercapacitors. The efficiency of a supercapattery is determined by its energy density, rate capabilities, and electrode reliability. In this study, a magnesium copper phosphate nanocomposite (MgCuPO4) was synthesized using a hydrothermal technique, and silver phosphate (Ag3PO4) was decorated on its surface using a sonochemical technique. Morphological analyses demonstrated that Ag3PO4 was closely bound to the surface of amorphous MgCuPO4. The MgCuPO4 nanocomposite electrode showed a 1138 C g-1 capacity at 2 A g-1 with considerably improved capacity retention of 59% at 3.2 A g-1. The increased capacity retention was due to the fast movement of electrons and the presence of an excess of active sites for the diffusion of ions from the porous Ag3PO4 surface. The MgCuPO4-Ag3PO4//AC supercapattery showed 49.4 W h kg-1 energy density at 550 W kg-1 power density and outstanding capacity retention (92% after 5000 cycles). The experimental findings for the oxygen evolution reaction reveal that the initial increase in potential required for MgCuPO4-Ag3PO4 is 142 mV, indicating a clear Tafel slope of 49 mV dec-1.

A bimetallic Fe-Mg MOF with a dual role as an electrode in asymmetric supercapacitors and an efficient electrocatalyst for hydrogen evolution reaction (HER).

In this work, a novel bimetallic Fe-Mg/MOF was synthesized through a cost-effective and rapid hydrothermal process. The structure, morphology, and composition were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy. Further, the Brunauer-Emmett-Teller (BET) measurement showed a 324 m2 g-1 surface area for Fe-Mg/MOF. The Fe-Mg/MOF achieved 1825 C g-1 capacity at 1.2 A g-1 current density, which is higher than simple Fe-MOF (1144 C g-1) and Mg-MOF (1401 C g-1). To assess the long-term stability of the asymmetric device, the bimetallic MOF supercapattery underwent 1000 charge/discharge cycles and retained 85% of its initial capacity. The energy and power densities were calculated to be 57 W h kg-1 and 2393 W kg-1, respectively. Additionally, Fe-Mg/MOF showed superior electrocatalytic performance in hydrogen evolution reaction (HER) by demonstrating a smaller Tafel slope of 51.43 mV dec-1. Our research lays the foundation for enhancing the efficiency of energy storage technologies, paving the way for more sustainable and robust energy solutions.

Exploring the redox characteristics of porous ZnCoS@rGO grown on nickel foam as a high-performance electrode for energy storage applications.

A supercapattery is a device that combines the properties of batteries and supercapacitors, such as power density and energy density. A binary composite (zinc cobalt sulfide) and rGO are synthesized using a simple hydrothermal method and modified Hummers' method. A notable specific capacity (Cs) of 1254 C g-1 is obtained in the ZnCoS@rGO case, which is higher than individual Cs of ZnS (975 C g-1) and CoS (400 C g-1). For the asymmetric (ASC) device (ZnCoS@rGO//PANI@AC), the PANI-doped activated carbon and ZnCoS@rGO are used as the cathode and anode respectively. A high Cm of 141 C g-1 is achieved at 1.4 A g-1. The ASC is exhibited an extraordinary energy density of 45 W h kg-1 with a power density 5000 W kg-1 at 1.4 A g-1. To check the stability of the device, the ASC device is measured for 2000 charging/discharging cycles. The device showed improved coulombic efficiency of 94%. These findings confirmed that the two-dimensional materials provide the opportunities to design battery and supercapacitor hybrid devices.

Improving the Energy Storage of Supercapattery Devices through Electrolyte Optimization for Mg(NbAgS)x(SO4)y Electrode Materials.

Electrolytes are one of the most influential aspects determining the efficiency of electrochemical supercapacitors. Therefore, in this paper, we investigate the effect of introducing co-solvents of ester into ethylene carbonate (EC). The use of ester co-solvents in ethylene carbonate (EC) as an electrolyte for supercapacitors improves conductivity, electrochemical properties, and stability, allowing greater energy storage capacity and increased device durability. We synthesized extremely thin nanosheets of niobium silver sulfide using a hydrothermal process and mixed them with magnesium sulfate in different wt% ratios to produce Mg(NbAgS)x)(SO4)y. The synergistic effect of MgSO4 and NbS2 increased the storage capacity and energy density of the supercapattery. Multivalent ion storage in Mg(NbAgS)x(SO4)y enables the storage of a number of ions. The Mg(NbAgS)x)(SO4)y was directly deposited on a nickel foam substrate using a simple and innovative electrodeposition approach. The synthesized silver Mg(NbAgS)x)(SO4)y provided a maximum specific capacity of 2087 C/g at 2.0 A/g current density because of its substantial electrochemically active surface area and linked nanosheet channels which aid in ion transportation. The supercapattery was designed with Mg(NbAgS)x)(SO4)y and activated carbon (AC) achieved a high energy density of 79 Wh/kg in addition to its high power density of 420 W/kg. The supercapattery (Mg(NbAgS)x)(SO4)y//AC) was subjected to 15,000 consecutive cycles. The Coulombic efficiency of the device was 81% after 15,000 consecutive cycles while retaining a 78% capacity retention. This study reveals that the use of this novel electrode material (Mg(NbAgS)x(SO4)y) in ester-based electrolytes has great potential in supercapattery applications.

The supercapattery designed with a binary composite of niobium silver sulfide (NbAg2S) and activated carbon for enhanced electrochemical performance.

A supercapattery is a hybrid device that is a combination of a battery and a capacitor. Niobium sulfide (NbS), silver sulfide (Ag2S), and niobium silver sulfide (NbAg2S) were synthesized by a simple hydrothermal method. NbAg2S (50/50 wt% ratio) had a specific capacity of 654 C g-1, which was higher than the combined specific capacities of NbS (440 C g-1) and Ag2S (232 C g-1), as determined by the electrochemical investigation of a three-cell assembly. Activated carbon and NbAg2S were combined to develop the asymmetric device (NbAg2S//AC). A maximum specific capacity of 142 C g-1 was delivered by the supercapattery (NbAg2S//AC). The supercapattery (NbAg2S/AC) provided 43.06 W h kg-1 energy density while retaining 750 W kg-1 power density. The stability of the NbAg2S//AC device was evaluated by subjecting it to 5000 cycles. After 5000 cycles, the (NbAg2S/AC) device still had 93% of its initial capacity. This research indicates that merging NbS and Ag2S (50/50 wt% ratio) may be the best choice for future energy storage technologies.

High performance and gate-controlled GeSe/HfS2 negative differential resistance device.

Transition metal dichalcogenides (TMDs) have received significant attention owing to their thickness-dependent folded current-voltage (I ds-V ds) characteristics, which offer various threshold voltage values. Owing to these astonishing characteristics, TMDs based negative differential resistance (NDR) devices are preferred for the realization of multi-valued logic applications. In this study, an innovative and ground-breaking germanium selenide/hafnium disulfide (p-GeSe/n-HfS2) TMDs van der Waals heterostructure (vdWH) NDR device is designed. An extraordinary peak-to-valley current ratio (≈5.8) was estimated at room temperature and was used to explain the tunneling and diffusion currents by using the tunneling mechanism. In addition, the p-GeSe/n-HfS2 vdWH diode was used as a ternary inverter. The TMD vdWH diode, which can exhibit different band alignments, is a step forward on the road to developing high-performance multifunctional devices in electronics.

Flexible Memory Device Composed of Metal-Oxide and Two-Dimensional Material (SnO2/WTe2) Exhibiting Stable Resistive Switching.

Two-terminal, non-volatile memory devices are the fundamental building blocks of memory-storage devices to store the required information, but their lack of flexibility limits their potential for biological applications. After the discovery of two-dimensional (2D) materials, flexible memory devices are easy to build, because of their flexible nature. Here, we report on our flexible resistive-switching devices, composed of a bilayer tin-oxide/tungsten-ditelluride (SnO2/WTe2) heterostructure sandwiched between Ag (top) and Au (bottom) metal electrodes over a flexible PET substrate. The Ag/SnO2/WTe2/Au flexible devices exhibited highly stable resistive switching along with an excellent retention time. Triggering the device from a high-resistance state (HRS) to a low-resistance state (LRS) is attributed to Ag filament formation because of its diffusion. The conductive filament begins its development from the anode to the cathode, contrary to the formal electrochemical metallization theory. The bilayer structure of SnO2/WTe2 improved the endurance of the devices and reduced the switching voltage by up to 0.2 V compared to the single SnO2 stacked devices. These flexible and low-power-consumption features may lead to the construction of a wearable memory device for data-storage purposes.

Ultrafast and Highly Stable Photodetectors Based on p-GeSe/n-ReSe2 Heterostructures.

Two-dimensional transition-metal dichalcogenide (2D-TMD) semiconductors and their van der Waals heterostructures (vdWHs) have attracted great attention because of their tailorable band-engineering properties and provide a propitious platform for next-generation extraordinary performance energy-harvesting devices. Herein, we reported unique and unreported germanium selenide/rhenium diselenide (p-GeSe/n-ReSe2) 2D-TMD vdWH photodetectors for extremely sensitive and high-performance photodetection in the broadband spectral range (visible and near-infrared range). A high and gate-tunable rectification ratio (RR) of 7.34 × 105 is achieved, stemming from the low Schottky barrier contacts and sharp interfaces of the p-GeSe/n-ReSe2 2D-TMD vdWHs. In addition, a noticeably high responsivity (R = 2.89 × 105 A/W) and specific detectivity (D* = 4.91 × 1013 Jones), with good external quantum efficiency (EQE = 6.1 × 105) are obtained because of intralayer and interlayer transition of excitations, enabling the broadband photoresponse (λ = 532-1550 nm) at room temperature. Furthermore, fast response times of 16-20 µs are estimated under the irradiated laser of λ = 1550 nm because of interlayer exciton transition. Such a TMD-based compact system offers an opportunity for the realization of high-performance broadband infrared photodetectors.

Highly Sensitive, Ultrafast, and Broadband Photo-Detecting Field-Effect Transistor with Transition-Metal Dichalcogenide van der Waals Heterostructures of MoTe2 and PdSe2.

Recently, van der Waals heterostructures (vdWHs) based on transition-metal dichalcogenides (TMDs) have attracted significant attention owing to their superior capabilities and multiple functionalities. Herein, a novel vdWH field-effect transistor (FET) composed of molybdenum ditelluride (MoTe2 ) and palladium diselenide (PdSe2 ) is studied for highly sensitive photodetection performance in the broad visible and near-infrared (VNIR) region. A high rectification ratio of 6.3 × 105 is obtained, stemming from the sharp interface and low Schottky barriers of the MoTe2 /PdSe2 vdWHs. It is also successfully demonstrated that the vdWH FET exhibits highly sensitive photo-detecting abilities, such as noticeably high photoresponsivity (1.24 × 105 A W-1 ), specific detectivity (2.42 × 1014 Jones), and good external quantum efficiency (3.5 × 106 ), not only due to the intra-TMD band-to-band transition but also due to the inter-TMD charge transfer (CT) transition. Further, rapid rise (16.1 µs) and decay (31.1 µs) times are obtained under incident light with a wavelength of 2000 nm due to the CT transition, representing an outcome one order of magnitude faster than values currently in the literature. Such TMD-based vdWH FETs would improve the photo-gating characteristics and provide a platform for the realization of a highly sensitive photodetector in the broad VNIR region.

Highly efficient self-powered perovskite photodiode with an electron-blocking hole-transport NiOx layer.

Hybrid organic-inorganic perovskite materials provide noteworthy compact systems that could offer ground-breaking architectures for dynamic operations and advanced engineering in high-performance energy-harvesting optoelectronic devices. Here, we demonstrate a highly effective self-powered perovskite-based photodiode with an electron-blocking hole-transport layer (NiOx). A high value of responsivity (R = 360 mA W-1) with good detectivity (D = 2.1 × 1011 Jones) and external quantum efficiency (EQE = 76.5%) is achieved due to the excellent interface quality and suppression of the dark current at zero bias voltage owing to the NiOx layer, providing outcomes one order of magnitude higher than values currently in the literature. Meanwhile, the value of R is progressively increased to 428 mA W-1 with D = 3.6 × 1011 Jones and EQE = 77% at a bias voltage of - 1.0 V. With a diode model, we also attained a high value of the built-in potential with the NiOx layer, which is a direct signature of the improvement of the charge-selecting characteristics of the NiOx layer. We also observed fast rise and decay times of approximately 0.9 and 1.8 ms, respectively, at zero bias voltage. Hence, these astonishing results based on the perovskite active layer together with the charge-selective NiOx layer provide a platform on which to realise high-performance self-powered photodiode as well as energy-harvesting devices in the field of optoelectronics.

Construction of 1T-MoS2 quantum dots-interspersed (Bi1-x Fe x )VO4 heterostructures for electron transport and photocatalytic properties.

The present study reports trigonal phase molybdenum disulfide quantum dots (MoS2/QDs)-decorated (Bi1-x Fe x )VO4 composite heterostructures. Initially, (Bi1-x Fe x )VO4 heterostructure nanophotocatalysts were synthesized through the hydrothermal method decorated with 1T-MoS2 via a sonication process. 1T-MoS2@(Bi1-x Fe x )VO4 heterostructures were characterized in detail for phase purity and crystallinity using XRD and Raman spectroscopy. The Raman mode evaluation indicated monoclinic, mixed monoclinic-tetragonal and tetragonal structure development with increasing Fe concentration. For physiochemical properties, SEM, EDX, XPS, PL, EPR, UV-visible and BET techniques were applied. The optical energy band gaps of 1T-MoS2@(Bi1-x Fe x )VO4 heterostructures were calculated using the Tauc plot method. It shows a blue shift initially within a monoclinic structure then a red shift with an increase of Fe concentration. 1T-MoS2@(Bi40Fe60)VO4 with 2 wt% of 1T-MoS2-QDs carrying a mixed phase exhibited higher photocatalytic activity. The enhanced photocatalytic activity is attributed to the higher electron transportation from (Bi1-x Fe x )VO4 surface onto 1T-MoS2 surface, consequently blocking the fast electron-hole recombination within (Bi1-x Fe x )VO4. 1T-MoS2 co-catalyst interaction with (Bi1-x Fe x )VO4 enhanced the light absorption in the visible region. The close contact of small 1T-MoS2-QDs with (Bi1-x Fe x )VO4 develops a high degree of crystallinity, with fewer defects showing mesoporous/nanoporous structures within the heterostructures which allows more active sites. Herein, the mechanism involved in the synthesis of heterostructures and optimum conditions for photocatalytic degradation of crystal violet dye are explored and discussed thoroughly.

A comparative study of electrical and opto-electrical properties of a few-layer p-WSe2/n-WS2 heterojunction diode on SiO2 and h-BN substrates.

Since the innovation of van der Waals heterostructures of 2D materials, the p-n junction diode, a building block of electronics and opto-electronics has been studied in various ways. To date most of them have been studied on SiO2 or other oxide substrates, although the oxide substrates cause significant degradation of the 2D material's intrinsic properties and device performances. Whereas using hexagonal boron nitride (h-BN) as an underlying layer to the 2D materials is known to preserve their properties. Here we have carefully analyzed the electrical and opto-electrical properties of a p-WSe2/n-WS2 van der Waals heterojunction diode on SiO2 and the h-BN substrates. Besides the usual enhancement of the field-effect mobility of WSe2 and WS2, we have achieved a significant enhancement of the diode rectification ratio and excellent photovoltaic characteristics on the h-BN substrate. We have obtained more than an order-of-magnitude enhancement of the diode rectification ratio and about two-fold increments in the overall opto-electronics behavior on the h-BN substrate compared with those on the SiO2 substrate. The values of self-powered photo responsivity and external quantum efficiency are 3 A/W and 588% respectively on the h-BN substrate at 10 mW cm-2 photo-power density and 633 nm wavelength, whereas they reduce to about one-half on the SiO2 substrate.

Cobalt-manganese-zinc ternary phosphate for high performance supercapattery devices.

State of the art supercapatteries have received considerable attention for their significant electrochemical performance; however, electrode materials with enhanced charge storage capabilities are desired. Here, we report the synthesis of mixed metal phosphate nanomaterials with different concentrations via a sonochemical approach. Initially, binary metal phosphates based on zinc, cobalt, and manganese were synthesized. Then, the composition of zinc and cobalt was optimized in ternary metal phosphates. Scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction techniques were utilized to examine the surface morphology, elemental analysis and crystal structure of as-synthesized nanomaterials. The electrochemical characterizations were performed in a three cell configuration. Zn0.50Co00.50Mn(PO4)2 delivers the optimum performance with a specific capacity of 1022.52 C g-1 (specific capacitance of 1704.21 F g-1) at 1.2 A g-1. This optimized material was further engaged in an asymmetric device (supercapattery) as a positive electrode material to explore the real device performance. The supercapattery device was found to have an impressive specific energy of 45.45 W h kg-1 at 0.5 A g-1 and provide a remarkable specific power of 4250 W kg-1 at 5 A g-1 current density. The device exhibits excellent capacity preservation of 93% examined after 1500 charge discharge cycles. In addition, to scrutinize the supercapattery performance in terms of capacitive and diffusion controlled processes, a simulation approach was adopted. The real device comprises a capacitive contribution of 8.42% at 3 mV s-1 and 66.56% at 100 mV s-1. This novel progress in ternary metal phosphates results in a fine electrode material for high performance supercapattery applications.

WS2/GeSe/WS2 Bipolar Transistor-Based Chemical Sensor with Fast Response and Recovery Times.

Vertical heterostructures of transition-metal dichalcogenide semiconductors have attracted considerable attention and offer new opportunities in electronics and optoelectronics for the development of innovative and multifunctional devices. Here, we designed a novel and compact vertically stacked two-dimensional (2D) n-WS2/p-GeSe/n-WS2 van der Waals (vdW) heterojunction bipolar transistor (2D-HBT)-based chemical sensor. The performance of the 2D-HBT vdW heterostructure with different base thicknesses is investigated by two configurations, namely, common-emitter and common-base configurations. The 2D-HBT vdW heterostructure exhibited intriguing electrical characteristics of current amplification with large gains of α ≈ 1.11 and ß ≈ 20.7. In addition, 2D-HBT-based devices have been investigated as chemical sensors for the detection of NH3 and O2 gases at room temperature. The effects of different environments, such as air, vacuum, O2, and NH3, were also analyzed in dark conditions, and with a light of 633 nm wavelength, ultrahigh sensitivity and fast response and recovery times (6.55 and 16.2 ms, respectively) were observed. These unprecedented outcomes have huge potential in modern technology in the development of low-power amplifiers and gas sensors.

High-Performance p-BP/n-PdSe2 Near-Infrared Photodiodes with a Fast and Gate-Tunable Photoresponse.

Van der Waals heterostructures composed of transition-metal dichalcogenide (TMD) materials have become a remarkable compact system that could offer an innovative architecture for advanced engineering in high-performance energy-harvesting and optoelectronic devices. Here, we report a novel van der Waals (vdW) TMD heterojunction photodiode composed of black phosphorus (p-BP) and palladium diselenide (n-PdSe2), which establish a high and tunable rectification and photoresponsivity. A high rectification up to ≈7.1 × 105 is achieved, which is successfully tuned by employing the back-gate voltage to the heterostructure devices. Besides, the device significantly shows the high and gate-controlled photoresponsivity of R = 9.6 × 105, 4.53 × 105 and 1.63 × 105 A W-1 under the influence of light of different wavelengths (λ = 532, 1064, and 1310 nm) in visible and near-infrared regions, respectively, because of interlayer optical transition and low Schottky. The device also demonstrates extraordinary values of detectivity (D = 5.8 × 1013 Jones) and external quantum efficiency (EQE ≈ 9.4 × 106), which are an order of magnitude higher than the currently reported values. The effective enhancement of photovoltaic characteristics in visible and infrared regions of this TMD heterostructure-based system has a huge potential in the field of optoelectronics to realize high-performance infrared photodetectors.