Metal Electrodes Research Articles

Direct Measurement of the Differential Capacitance of Deep Eutectic Solvents on Platinum and Glassy Carbon Electrodes.

Differential capacitance is a crucial parameter that connects the experimental observation of electrical double-layer behavior with theoretical models. However, the current number of reported differential capacitance values for deep eutectic solvents remains limited, making it challenging to verify or refute existing models. In this study, we systematically investigate the differential capacitance in deep eutectic solvents using chronoamperometry. By comparing metal and glassy carbon electrodes across various liquid combinations and ion concentrations, we observed a range of distinct capacitance characteristics. While some findings align with the existing mean-field model for ionic liquids, others clearly reflect the influence of electrode materials, with certain cases resisting full explanation by current theoretical models. These results underscore the importance of selecting appropriate electrode materials in experimental studies of such electrolytes and highlight the need for further theoretical advancements in understanding this complex liquid system.

Phosphate Ion-Selective Electrode Based on Electrochemically Modified Iron.

The significance of the detection of phosphate ions is immense in the realms of chemistry, biology, medicine, environment, and industry. The detection of phosphate ions is currently mainly reliant on blue molybdenum colorimetry, which is accurate but requires sample pretreatment, intricate operation, and a high price tag. Consequently, it is essential to create a sensor with superior efficiency, precision, straightforward functioning, and instantaneous online detection. This study has designed and created an electrochemical modification based on an iron metal electrode for this purpose. Cyclic voltammetry was used to initially ascertain the potential (-0.57 V) necessary for constant potential electrolysis. Employing a constant potential electrolysis method, the iron oxide and its phosphate were modified onto the surface of the iron electrode to enable reaction with phosphate ions. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to characterize and analyze the morphology and elemental composition of Fe-PME, elucidating how it responds to phosphate ionation. The two-electrode system was then utilized for the evaluation of the phosphate ion response of Fe-PME at pH 4. Fe-PME's response to phosphate ions is demonstrated by the results, ranging from 10-5 to 0.1 M and with a slope of -52.8 mV dec-1. Fe-PME exhibited satisfactory results when compared to the conventional blue colorimetry of molybdenum.

Hearing triboelectricity: home experiments

Abstract This study explores the demonstration of triboelectricity using everyday materials in a home experiment setting. By rubbing Teflon against metallic electrodes (aluminum and copper), we generated significant voltage due to Teflon’s strong electron acceptor properties. Aluminum exhibited higher voltage generation than copper, attributed to a greater electron affinity difference. To showcase practical applications, we successfully illuminated LEDs and powered a Bluetooth speaker, using the voltage generated from Teflon-metal interactions. This simple yet effective setup highlights the potential of triboelectric materials for sustainable energy harvesting and underscores the accessibility of home-based experiments in advancing scientific understanding.

Enhancement of tunneling electroresistance in metal/two-dimensional ferroelectric tunnel junctions: route for polarization-modulated interface transport

In fabricating ferroelectric tunnel junction (FTJ) devices, it is essential to employ low-resistance metals as electrodes interfacing with two-dimensional (2D) ferroelectric materials. For FTJs with a top contact configuration, two interfaces for charge transport are present, namely the vertical interface between the metal electrode and the 2D ferroelectric material, and the lateral interface between the electrode and the central scattering region. These interfaces significantly influence the tunneling electroresistance (TER) of FTJs. However, there exists a notable deficiency in comprehension concerning the physics of charge transport at the interface. In this work, we explore the interface transport properties in FTJs featuring a top contact configuration between metal and the typicalα-In2Se3monolayer. By employing the non-equilibrium Green's function method, we observe a TER ratio of1.15×105% for the Pd top contact interfacing with anα-In2Se3monolayer. The significant TER effect is attributed to polarization-controlled interface transport, which is further elucidated through an analysis of the transport mechanisms influenced by the out-of-plane polarization ofα-In2Se3at the vertical interface and the in-plane polarization at the lateral interface. This investigation of the fundamental physical mechanisms of polarization-controlled interface transport demonstrates significant potential for enhancing non-volatile memory devices.

Modeling and Optimization of Modified TiO2 with Aluminum and Magnesium as ETL in MAPbI3 Perovskite Solar Cells: SCAPS 1D Frameworks.

The perovskite device, incorporating a modified nanostructure of TiO2 as the electron transport layer, has been investigated to enhance its performance compared to the pure TiO2 device. Various materials undergo electrochemical doping or treatment on TiO2 to improve their photocatalytic application, thereby enhancing the current density, minimizing recombination, and improving device stability. In this study, a numerical SCAPS simulation was employed to validate experimental findings from the literature. According to the literature, this marks the first instance of doping Al3+ and Mg2+ on TiO2 due to their ionic radius comparable to that of Ti4+, at different doping concentrations. The device was modeled and simulated with the experimental parameters of bandgap, series, and shunt resistances for pure TiO2, aluminum-doped TiO2 (Al-TiO2), and magnesium-doped TiO2 (Mg-TiO2). From the validated results, the Al-TiO2 and Mg-TiO2-based devices' configurations with minimum percentage errors of 0.427 and 2.771%, respectively, were selected and simulated across nearly 90 (90) configurations to determine the optimum device model. Optimizing absorber thickness, bandgap, doping concentration, metal electrode, as well as series and shunt resistance resulted in enhanced device performance. According to the proposed model, Al-TiO2 and Mg-TiO2 configurations achieved higher power conversion efficiency values of 19.260 and 19.860%, respectively. This improvement is attributed to the reduction in recombination rates through the injection of a higher photocurrent density.

Evaluation of Oxide|Sulfide Heteroionic Interface Stability for Developing Solid-State Batteries with a Lithium-Metal Electrode: The Case of LLZO|Li6PS5Cl and LLZO|Li7P3S11.

Developing solid-state batteries (SSB) with a lithium metal electrode (LME) using only one type of solid electrolyte (SE) is a significant challenge since no SE fits all the requirements imposed by both electrodes. A possible solution is using multilayer SSBs with an LME where the drawbacks of each SE are overcome by using layers of different SEs. However, research on inorganic SE1|SE2 heteroionic interfaces is still quite preliminary, especially regarding oxide|sulfide heteroionic interfaces. This work reports the electrochemical investigation of the heteroionic interface between Li6.25Al0.25La3Zr2O12 (Al-LLZO) and two representative materials for sulfide-based SEs: argyrodite-based Li6PS5Cl (LPSCl) and glass-like Li7P3S11 (LPS711). Through in-depth temperature- and pressure-dependent impedance analyses of multilayer symmetric cells at equilibrium (i.e., no current load), the electrical properties of the heteroionic interfaces are assessed. The pressure-dependent kinetic of the Al-LLZO|LPSCl pair is interpreted with the concept of geometric constriction resistance and show that its resistance is lower than for the Al-LLZO|LPS711 pair. Furthermore, the effect of Al-LLZO surface treatment on the electrical properties of the Al-LLZO|LPSCl heteroionic interface is evaluated. Such investigation shows that the value of the interface activation energy decreases when the Al-LLZO surface is heat treated, revealing a significant influence of the carbonate/hydroxide passivation layer on the heteroionic interface. Additionally, by cycling the symmetric cell for 900 h at 1.0 mAh·cm-2, it is revealed that the Al-LLZO|LPSCl interface has a lower impedance increase than the Al-LLZO|LPS711 interface, especially if the Al-LLZO is heat treated. With this work, we highlight that the oxide|argyrodite combination can be a promising candidate for multilayer SSBs with an LME. However, we show that an optimized LLZO surface treatment and chemical analysis of the interface are recommended for future research.

Fabrication of cost-effective lead-free silver bismuth iodide based mesoscopic Rudorffite solar cells

Lead-free Ag–Bi–I Rudorffite materials, specifically AgBiI4, Ag2BiI5, Ag3BiI6 and AgBi2I7, have garnered substantial attention as prospective alternatives to lead halide perovskites in solar cell technology. Rudorffite-based solar cells have conventionally employed a mesoporous structure, integrating unstable and costly hole-transport layers (HTLs) in conjunction with noble metal electrodes. This study presents carbon-based, all-inorganic AgBiI4, Ag2BiI5, Ag3BiI6 and AgBi2I7 Rudorffite solar cells that circumvent the need for HTLs and noble metal electrodes. The absorber layers composed of AgBiI4, Ag2BiI5, Ag3BiI6 and AgBi2I7 materials were synthesized via melt-solidification. Notably, Ag2BiI5 based solar cell achieved PCE of 0.93 % among all the Silver Bismuth Iodide (SBI) devices which is the highest efficiency reported for Ag2BiI5 solar cell to date. The corresponding solar cell parameters include an open-circuit voltage (Voc) of 0.634 V and a short-circuit current (Jsc) of 3.63 mA/cm2. Consequently, our work presents a pathway toward developing Rudorffite solar cells with simplified fabrication methods and reduced cost.

Zero‐Bias Anti‐Ohmic Behaviour in Diradicaloid Molecular Wires

AbstractOpen‐shell materials bearing multiple spin centres provide a key route to efficient charge transport in single‐molecule electronic devices. They have narrow energy gaps, and their molecular orbitals align closely to the Fermi level of the metallic electrodes, thus allowing efficient electronic transport and higher conductance. Maintaining and stabilising multiple open‐shell states—especially in contact with metallic electrodes—is however very challenging, generally requiring a continuous chemical or electrochemical potential to avoid self‐immolation of the open‐shell character. To overcome this issue, we designed, synthesised, and measured the conductance of a series of bis(indeno) fused acenes, where stability is imparted by a close‐shell quinoidal conformation in resonance with the diradical electronic configuration. We show here that these compounds have anti‐ohmic behaviour, with conductance increasing with increasing molecular length, at an unprecedented rate and across the entire bias window ( ). Density Functional Theory (DFT) calculations support our findings, showing the rapidly narrowing HOMO–LUMO gap, unique to these diradicaloid structures, is responsible for the observed behaviour. Our results provide a framework for achieving efficient transport in neutral compounds and demonstrate the promise that diradicaloid materials have in single‐molecule electronics, owing to their great stability and unique electronic structure.

Additive-assisted passivating manipulation for printable carbon-based CsPbBr3 perovskite quantum dots solar cells with stacked structure

Carbon-based perovskite solar cells (PSCs) have attracted attention as low-cost and facile fabrication process. However, the ionic nature of perovskite and nonradiative recombination at perovskite/carbon interface are present inevitable obstacles in approaching their highly efficiency. Herein, the multifunctional molecules of zinc oxalate is implanted into the precursor of perovskite to passivate defects and narrowing the interface energy barrier, and a flexible method of screen-printing employed in prepare stacked structure device ITO/SnO2/CsPbBr3•x % ZnOX //CQDs/ITO. In this regard, CQDs are used as carbon electrodes to replace expensive materials of hole transport layer and precious metal electrode, in which CQDs extracted from sugarcane molasses, a cheap by-product of native sugar industry. Additionally, the stacked structure composed of a photoanode (ITO/SnO2/CsPbBr3•x % ZnOX) and back electrode (CQDs/ITO) exhibits a promising prospect in photovoltaic application. Finally, the power conversion efficiency of 2 % ZnOX modified PSCs increases to 1.96 %, and the improvement rate has reached 1.54 times. In addition, modified PSCs with a greater stability compared with that of the control device. This work presents a useful approach to passivate defects and provides a cost-effective option to fabricate devices with stacked structure.

Unveiling Versatile Electronic Properties and Contact Features of Metal-Semiconductor Graphene/γ-Ge2SSe van der Waals Heterostructures.

Recently, searching for a metal-semiconductor junction (MSJ) that exhibits low-contact resistance has received tremendous consideration, as they are essential components in next-generation field-effect transistors. In this work, we design a MSJ by integrating two-dimensional (2D) graphene as the metallic electrode and 2D Janus γ-Ge2SSe as the semiconducting channel using first-principles simulations. All the graphene/γ-Ge2SSe MSJs are predicted to be energetically, mechanically, and thermodynamically stable, characterized by the weak van der Waals (vdW) interactions. The graphene/γ-SGe2Se MSJ-vdWH form the n-type Schottky contact (SC), while the graphene/γ-SeGe2S MSJ-vdWH form the p-type one, suggesting that the switching between p-type and n-type SC in the graphene/γ-Ge2SSe MSJ-vdWHs can occur spontaneously by simply altering the stacking patterns, without requiring any external conditions. Notably, the contact features, including contact types and barriers of the graphene/γ-Ge2SSe MSJs are significant in versatility and can be altered by applying electric gating and adjusting interlayer spacing. Both the applied electric gating and strain engineering induce switchability between p- and n-type and SC to OC in the graphene/γ-Ge2SSE MSJs. This versatility underscores the potential of the graphene/γ-Ge2SSe MSJ for next-generation applications that require low-contact resistance and high performance.

A simple route of providing a soft interface for PEDOT: PSS film metallic electrodes without loss of their electrical interface parameters

The work presents the development of a soft interface at PEDOT:PSS film without changing its electrical interface parameters. In the first step, PEDOT:PSS is electrodeposited on the commercial platinum electrode under the state-of-the-art conditions desirable for different electrochemical electrodes. Secondly, a pure hydrogel layer is deposited on the top of the electrodeposited PEDOT:PSS film under conditions that provide desirable mechanical properties (Young's modulus ∼10–20 kPa) and high permeability to ions from the solution. As a result, a PEDOT:PSS electrode with a soft interface desirable for different electrode applications is fabricated. The electrode exhibits electrical parameters at the same level as the state-of-the-art PEDOT:PSS film applied already for electrode applications. Moreover, the hydrogel layer additionally supports the polymeric film's electrochemical stability by inhibiting its oxidative degradation. The thickness of PEDOT film does not affect the overall electrochemical properties of the hydrogel electrode. The work shows that the specific choice of the hydrogel type and fabrication conditions allows to synthesis of the hydrogel interface on a stiff polymeric film, which does not block the ionic and electrical transfer. Moreover, the fabricated PEDOT:PSS electrode with hydrogel interface reveals interfacial impedance and potential window comparable or even better to the already published studies on PEDOT:PSS hydrogels.

A Micromachined Silicon-on-Glass Accelerometer with an Optimized Comb Finger Gap Arrangement.

This paper reports the design, fabrication, and characterization of a MEMS capacitive accelerometer with an asymmetrical comb finger arrangement. By optimizing the ratio of the gaps of a rotor finger to its two adjacent stator fingers, the sensitivity of the accelerometer is maximized for the same comb finger area. With the fingers' length, width, and depth at 120 μm, 4 μm, and 45 μm, respectively, the optimized finger gap ratio is 2.5. The area of the proof mass is 750 μm × 560 μm, which leads to a theoretical thermomechanical noise of 9 μg/√Hz. The accelerometer has been fabricated using a modified silicon-on-glass (SOG) process, in which a groove is pre-etched into the glass to hold the metal electrode. This SOG process greatly improves the silicon-to-glass bonding yield. The measurement results show that the resonant frequency of the accelerometer is about 2.05 kHz, the noise floor is 28 μg/√Hz, and the nonlinearity is less than 0.5%.

Liquid metal based flowable regenerative catalyst for electrochemical nitrate reduction

Electrocatalytic reduction nitrate to ammonia as a complementary production method has attracted much attention. However, in the most situation, the catalyst are fixed at certain location. The immobile active sites may suffer from mass transfer limitation and deactivation. In this study, based on the fluidity and alloying ability of liquid metal gallium, we fabricated a flowable and regenerative CuGa2-liquid metal electrode for the electrochemical nitrate reduction. The flowing surface accelerate the reactants reaching catalyst, leading a higher mass transfer coefficient than the solid surface. During the catalytic process, a performance decay was found and the deactivation mechanism was revealed as catalyst detachment resulting from interface evolution. A regeneration strategy has been proposed for rapid repairment in seconds. The strategy results in an extended lifespan approximately ∼1500 % longer than control group.

Realizing n-type carbon nanotubes via halide perovskite nanowires Cs4MX5 inner filling

N-type carbon nanotubes (CNTs)-based field-effect transistors (FETs) have huge potential applications in low-power consumption tunnel FETs. However, the low-work function metal electrodes can achieve n-type CNTs, but they are easily oxidized due to poor environmental stability. Therefore, based on first-principles calculations, we proposed halide perovskite nanowires Cs4MX5 (M = Pb, Sn; X = Cl, Br, I) inner filling to achieve n-type single-walled CNTs (SWCNTs). The results indicated that all the perovskite nanowires located at the center of the SWCNTs possess high stability. Moreover, the diameter of SWCNTs is a crucial factor affecting the inner filling of perovskite nanowires with an optimal diameter of about 1.4 nm. Furthermore, all the perovskite nanowires Cs4MX5 are excellent electron donors, and the largest charge transfer is up to 1.72 e/nm for Cs4SnI5. Their interaction mechanism reveals that the low work function and the large internal bandgap are two important factors for cubic-phase nanowires to realize the n-type CNTs. Our findings provide some candidate materials and a feasible way to achieve n-type CNTs for applying CNTs-based FETs.

Modulating the doping level of conductive polymers for all polymer-based triboelectric self-powered sensors

Triboelectric self-powered sensors, utilizing flexible conductive polymers in place of traditional metal electrodes, provide improved flexibility and reduced weight, making them highly promising for next-generation Internet of Things sensing applications. Here we demonstrate that ionic liquid (IL) additives notably enhance the mechanical and electrical properties of conductive polymer (PEDOT:PSS) films, optimizing their triboelectric performance. Results show that IL as molecular dopant induces structural change in PEDOT, thereby enhancing charge delocalization and doping levels. These IL-doped PEDOT:PSS films achieved high conductivity, significantly elevated surface potential, and a fourfold increase in output triboelectric voltage compared to the neat film. Additionally, flexible all-polymer tactile sensors with high sensitivity (3.6 V/kPa) were fabricated, demonstrating potential for diverse applications such as activity signal detection and human–machine interfaces.

Optimizing Hybrid Perovskites for High-Efficiency Solar Energy

Our research explores hybrid perovskite solar cells, promising low-cost and high-efficiency photovoltaic solutions. Despite challenges, optimizations like interface engineering enhance performance for future commercial use. Study of different physical parameters with the help of SILVACO and MATLAB Simulink for cell modeling. Long-term stability and cost reductions are among the most significant challenges to broad commercialization Future research will be around trying different parameter values. There searcher said this project represents an important step forward in the development of hybrid perovskite solar cells, which could be a key partof a new wave of clean energy sources that are needed as global consumption levels continue to rise. The solar cells studied herein are detailed by the six-scan structure: Glass/Indium Tin Oxide (ITO) / Electron Transport Layer - (N layer) - Active Layer (Perovskite) - Hole transport_layer (Payer) - Metal Electrode; Glass/ITO/TiO2/Pero_Aardes Spiro-OMeTAD/Au. It delivers the energy conversion efficiency of 19.12% with a fill factor (FF) of 80.53%, an open-circuit voltage at Voc =1.14 Vandshort circuit current density Jsc=20.88 mA/cm²,respectively The active layer is a 0.25 -thick CH3NH3PbI3 perovskite, and the TiO2 layer thickness was set at 0.02

Memristors with Monolayer Graphene Electrodes Grown Directly on Sapphire Wafers.

The development of the memristor has generated significant interest due to its non-volatility, simple structure, and low power consumption. Memristors based on graphene offer atomic monolayer thickness, flexibility, and uniformity and have attracted attention as a promising alternative to contemporary field-effect transistor (FET) technology in applications such as logic and memory devices, achieving higher integration density and lower power consumption. The use of graphene as electrodes in memristors could also increase robustness against degradation mechanisms, including oxygen vacancy diffusion to the electrode and unwanted metal ion diffusion. However, to realize this technological transformation, it is necessary to establish a scalable, robust, and cost-effective device fabrication process. Here we report the direct growth of high-quality monolayer graphene on sapphire wafers in a mass-producible, contamination-free, and transfer-free manner, using a commercially available metal-organic chemical vapor deposition (MOCVD) system. By taking advantage of this approach, graphene-electrode based memristors are developed, and all the processes used in the device fabrication incorporating graphene electrodes can be performed at wafer scale. The graphene electrode-based memristor demonstrates promising characteristics in terms of endurance, retention, and ON/OFF ratio. This work presents a possible and viable route to achieving robust graphene-based memristors in a commercially and technologically sustainable manner, paving the way for the realization of more powerful and compact integrated graphene electronics in the future.

MemriSim: A theoretical framework for simulating electron transport in oxide memristors

We have developed a theoretical framework MemriSim for simulating the resistive switching behaviors of oxide memristors. MemriSim comprises two major parts, i) structural evolution of oxygen vacancies during conductive filament formation/rupture by kinetic Monte Carlo (kMC) algorithm, and ii) transport calculations based on the scenario of electron tunneling and thermionic emission with the kMC derived structures. As prototype probes, we have computed the current-voltage (I-V) curves of HfO2 and TaOx based memristors and compared the results with experimental measurements, which show perfect agreement. By tuning the physical parameters, MemriSim can describe resistive switching devices with different oxide layers and metal electrodes. In addition, the pulse transient current can also be simulated by considering the transient response of RLC circuit. The developed framework not only provides a general approach for understanding the fundamental mechanism of resistive switching in oxides, but also opens up new opportunities for designing and optimizing memristor-based architectures for nonvolatile memory, logic-in-memory and neuromorphic computing.Program summaryProgram Title: MemriSim.CPC Library link to program files: https://doi.org/10.17632/8gbbgf8z49.1Licensing provisions: GPLv2.Programming language: C++.Supplementary material: Supplementary material is available.Nature of problem: A general framework for simulating the resistive switching properties of oxide-based memristors; generate the structure of oxide layer during filament formation/rupture; calculate the I-V curves of memristive device; simulate the pulse transient current; predict the resistive switching performance of new devices.Solution method: The framework uses kMC algorithm for structural evolution, the electric field inside oxide layer is computed by the Poisson's equation, and the transport calculation is based on electron tunneling and thermionic emission.

Exploring charge transfer and schottky barrier modulation at monolayer Ge2Sb2Te5-metal interfaces

Monolayer Ge2Sb2Te5exhibits great potential in non-volatile memory technology due to its excellent electronic properties and phase-change characteristics, while the fundamental nature of Ge2Sb2Te5-metal contacts has not been well understood yet. Here, we provide a comprehensiveab initiostudy of the electronic properties between monolayer Ge2Sb2Te5and Pt, Pd, Au, Cu, Cr, Ag, and W contacts based on first-principles calculations. We find that the strong interaction interfaces formed between monolayer Ge2Sb2Te5and Pt, Pd, Cr, and W contacts show chemical bonding and strong charge transfer. In contrast, no apparent chemical bonding and weak charge transfer are observed in the weak interaction interfaces formed with Au, Cu, and Ag. Additionally, our study reveals the presence of a pronounced Fermi level pinning effect between monolayer Ge2Sb2Te5and metals, with pinning factors ofSn=0.325andSp=0.350. By increasing the interlayer distance, an effective transition fromn-type Ohmic contact ton-type Schottky contact is facilitated because the band edge of Ge2Sb2Te5is shifted upwards. Our study not only provides a theoretical basis for selecting suitable metal electrodes in Ge2Sb2Te5-based devices but also holds significant implications for understanding Schottky barrier height modulation between semiconductors and metals.

Topological van der Waals Contact for Two-Dimensional Semiconductors.

The relentless miniaturization inherent in complementary metal-oxide semiconductor technology has created challenges at the interface of two-dimensional (2D) materials and metal electrodes. These challenges, predominantly stemming from metal-induced gap states (MIGS) and Schottky barrier heights (SBHs), critically impede device performance. This work introduces an innovative implementation of damage-free Sb2Te3 topological van der Waals (T-vdW) contacts, representing an ultimate contact electrode for 2D materials. We successfully fabricate p-type and n-type transistors using monolayer and multilayer WSe2, achieving ultralow SBH (∼24 meV) and contact resistance (∼0.71 kΩ·μm). Simulations highlight the role of topological surface states in Sb2Te3, which effectively mitigate the MIGS effect, thereby significantly elevating device efficiency. Our experimental insights revealed the semiohmic behavior of Sb2Te3 T-vdW contacts, with an exceptional photoresponsivity of 716 A/W and rapid response times of approximately 60 μs. The findings presented herein herald topological contacts as a superior alternative to traditional metal contacts, potentially revolutionizing the performance of miniaturized electronic and optoelectronic devices.