Van der Waals two-dimensional materials are drawing increasing interest for nanoelectronics and optoelectronic applications. Their atomically thin channels and clean interfaces help overcome several scaling constraints faced by silicon technologies at the nanoscale, positioning them as leading candidates for next-generation electronics. To be truly competitive, however, they must also match silicon's key strengths such as high processing quality, high carrier mobility, effective broadband optical response, and tunable carrier density and type through doping. While some of the required features have been widely demonstrated, controlling electronic properties through conventional doping techniques remains challenging. Against this backdrop, ternary alloys of transition- and post-transition-metal dichalcogenides are emerging as a practical route: they retain the advantages of their binary parents while offering compositional tunability for bandgap and electronic properties. Here, we report fieldeffect transistors based on single SnSSe-alloy flakes (atomic ratio Sn:S:Se = 1:1:1) and present a comprehensive assessment of their electrical and optoelectronic properties in the dark and under illumination, at both ambient pressure and under vacuum. We obtain a maximum carrier mobility of 2.84 cm2 V- 1 s- 1 and a remarkable peak responsivity of more than 100 A/W at 460 nm. In addition to positive photoconduction, which decreases with increasing wavelength, we observe negative photoconductivity across the entire investigated range from 460 to 1000 nm, with a significant infrared responsivity of 2.85 A/W at 860 nm. The mechanisms underlying both positive and negative photoconductivities are analyzed in detail, and a phenomenological model is proposed to explain their origin, emphasizing the role of SnSSe-alloy-substrate coupling.

2D semiconductors are attracting considerable interest for neuromorphic electronics for their strong light-matter interaction, defect-mediated charge dynamics, and suitability for energy-efficient devices. Among them, tin diselenide (SnSe2) combines Earth abundance, environmental stability, high carrier mobility and persistent photoconductivity that make it a compelling candidate for multifunctional optoelectronic synapses. Here, we investigate multilayer SnSe2 field-effect transistors and demonstrate gate-tunable optoelectronic plasticity. Systematic measurements as a function of temperature, illumination power, and gate bias reveal that the device photoresponse is dominated by trap-assisted photogating. The interplay between fast and slow recombination channels produces a persistent photocurrent (PPC) that can be finely tuned by the gate voltage. Negative gate bias enhances charge separation and prolongs PPC, enabling long-term potentiation, while positive gate bias accelerates recombination and suppresses persistence, yielding short-term memory. Furthermore, short gate voltage pulses enable reversible suppression of persistent photocurrent, allowing controlled switching between short- and long-term memory states. Under repetitive optical stimulation, the devices exhibit cumulative learning and memory retention with high reproducibility. These results highlight SnSe2 as a robust platform for optoelectronic neuromorphic devices. By exploiting interfacial trap states and gate control, SnSe2-based transistors emulate essential synaptic functionalities with excellent stability, offering new opportunities for 2D-material-enabled scalable neuromorphic hardware.

This report is on the field emission properties of WSe 2 nanoflowers synthesized via a solution‐phase colloidal approach, uniformly deposited on Si/SiO 2 substrates. Structural and spectroscopic data confirm the formation of highly crystalline nanoflowers with predominantly 1T′ phase content and minimal surface oxidation. Field emission measurements, performed in vacuum using a nanomanipulated tungsten probe, reveal a low turn‐on voltage and a field enhancement factor ranging from ≈70 at cathode‐anode separation distance of 100 nm, to ≈10 for distance increased to 900 nm, as resulting by the analysis in the framework of the Fowler–Nordheim model. WSe 2 nanoflowers offer competitive performance combined with excellent stability, attributable to their hierarchical architecture and metallic character. These results demonstrate the potential of WSe 2 nanoflowers as efficient cold cathode materials for next‐generation vacuum electronic applications.

Tin disulfide (SnS2) is a 2D semiconductor with a wide bandgap exceeding 2.0 eV. A detailed electrical study of back-gated Schottky-barrier field-effect transistors (FETs) based on multilayer SnS2 channels is presented. The devices display n-type conduction, with current levels increasing with temperature due to thermally activated transport across the contacts. A pronounced hysteresis appears in the transfer characteristics, growing linearly with temperature at a rate of approximate to 0.5 V K-1, revealing a temperature-sensitive response that can be explored for sensing functionalities. Remarkably, the same temperature dependence enhances the memory functionality of the devices: the memory window broadens with increasing temperature, and both retention and endurance improve, in contrast to conventional memory technologies. The observed behavior is linked to the modulation of carrier transport at the contacts, where environmental exposure induces barrier asymmetries and inhomogeneities, as confirmed by analysis using the G & uuml;ttler-Werner model. These results suggest that SnS2-based FETs may be exploited either for sensing or memory functionality, depending on the operating conditions, outlining a conceptual route toward compact and reconfigurable components in future 2D electronic systems.

Solution-processed graphene is extremely attractive for the realization of large area and patterned graphene films for field emitting devices. Previous studies have focussed only on the use of reduced graphene oxide; however, solution-processed graphene can also be produced by other approaches, giving rise to nanosheets with different surface chemistries and lateral and thickness distributions. Here, we report the field emission characterization of films made of water-based graphene ink, prepared by liquid phase exfoliation, and inkjet printed with an area of 2.5 mm2 on silicon (Si/SiO2) substrates. These films show excellent field emission properties, comparable to those measured on single flakes and carbon nanotubes with the same setup, and they show a remarkably high maximum current density (up to ∼723 A cm-2), making them very attractive for field emission devices.

We report the fabrication and characterization of flexible cold cathodes based on graphite nanoplatelet (GNP) coatings on silicone rubber substrates. GNPs, synthesized via thermal exfoliation of graphite bisulfate and sonication in acetone, form nanostructured coatings with controlled roughness and thickness. Morphological, structural, and spectroscopic analyses confirm the presence of crystalline, few-layer graphitic domains. Field emission was locally probed by using a nanomanipulated tungsten tip anode inside a scanning electron microscope, revealing a turn-on voltage as low as 8.2 V and a field enhancement factor of similar to 80 at an anode-cathode distance of 100 nm. Emission characteristics are measured in different substrate curvature configurations: sharper bending alters the exposure of nanoplatelet edges, influencing the turn-on voltage and the field enhancement factor. The emitters exhibit excellent stability, robustness under strain, and thermally activated conduction behaviour with an activation energy of similar to 0.31 eV. Our findings demonstrate that GNP-coated silicone rubbers are a scalable, low-cost, and mechanically adaptive platform for next-generation vacuum microelectronics, enabling flexible, high-performance electron sources with nanoscale control and real-time tunability.

This report is on the field emission properties of WSe2 nanoflowers synthesized via a solution-phase colloidal approach, uniformly deposited on Si/SiO2 substrates. Structural and spectroscopic data confirm the formation of highly crystalline nanoflowers with predominantly 1T ' phase content and minimal surface oxidation. Field emission measurements, performed in vacuum using a nanomanipulated tungsten probe, reveal a low turn-on voltage and a field enhancement factor ranging from approximate to 70 at cathode-anode separation distance of 100 nm, to approximate to 10 for distance increased to 900 nm, as resulting by the analysis in the framework of the Fowler-Nordheim model. WSe2 nanoflowers offer competitive performance combined with excellent stability, attributable to their hierarchical architecture and metallic character. These results demonstrate the potential of WSe2 nanoflowers as efficient cold cathode materials for next-generation vacuum electronic applications.

In this study, we present a hybrid optoelectronic device consisting of tungsten disulfide nanotubes (NTs) deposited on graphene electrodes, forming ohmic contacts that enable efficient charge transport. The heterostructure is fabricated on a flexible polyethylene terephthalate substrate. Comprehensive electrical and optoelectronic characterizations are conducted under various environmental conditions, with a focus on photocurrent response and the photovoltaic effect. The device shows a broadband photoresponse from 405 to 900 nm, reaching its best performance at 880 nm, where it delivers a peak responsivity of 0.07 mA W-1, a specific detectivity of 2.3 × 107Jones and rise/decay constants of 1.6 s/1.5 s, measured under 405 nm illumination at an incident power of 0.19 mW. A long-time tail of 23 s is also observed, attributed to trap-assisted processes. The long-wavelength cut-off (∼ 880 nm) corresponds to an indirect bandgap of 1.4 ± 0.1 eV for the NTs. Under 520 nm illumination, the heterostructure generates an open circuit photovoltage of ∼15 mV and a short-circuit photocurrent of ∼0.08 nA, confirming the presence of a photovoltaic effect. Illumination at 405 nm reveals a photocurrent response that is sensitive to changes in environmental pressure. These results highlight the multifunctionality of the heterostructure, which can be optimized for photovoltaic conversion, wearable photodetectors, and sensing applications.

We report on the synthesis, fabrication, and optoelectronic characterization of a field-effect transistor (FET) based on a multilayer SnS2 flake. The device was fabricated by mechanical exfoliation of single crystals grown via chemical vapor transport and transferred onto SiO2/Si substrates. Electrical measurements under vacuum reveal nearly symmetric output curves, indicating low Schottky barriers, and an n-type behavior with an ON/OFF ratio ~100. Photodetection measurements under monochromatic laser illumination (from 420 to 800 nm) show a highly wavelength-dependent responsivity, peaking at ~100 A/W. Under ambient conditions the device behavior changes dramatically, showing strong asymmetry in output curves and increased hysteresis are observed due to oxygen-enhanced Schottky barriers and trap states. A power-law fitting of the photocurrent reveals α ≈ 1.23 in vacuum, indicative of efficient photogeneration, and α ≈ 0.63 in air, highlighting the role of trap-assisted processes. Time-resolved measurements reveal how this trap states induce gate-tunable persistent photoconductivity, which demonstrate the strong versatility of SnS2-based devices for tunable optoelectronic applications.

The electrical and optoelectronic properties of a SnSe2-based field-effect transistor as a function of temperature and optical excitation are presented. The device was characterized electrically through output and transfer curves measurements in the temperature range of 220 K to 390 K. Transfer measurements confirm n-type conduction. Field-effect mobility, extracted from transfer curves, decreases from 53 to 46 cm2 V⁻1 s⁻1 with increasing temperature. To evaluate the photoresponse, the device was illuminated with a supercontinuum laser. The photocurrent exhibits sublinear dependence on optical power at low temperatures and long characteristic decay time, indicative of a photogating mechanism. Responsivity decreases with temperature, from 1.82 A/W at 220 K to 0.24 A/W at 390 K. The photocurrent dependence on light power becomes progressively more linear at higher temperatures, and a transition from photogating-dominated to photoconductive behavior occurs. The influence of gate voltage on photoresponse was further investigated. A slow decay time of the photocurrent at negative gate voltages confirms persistent photogating, which is mitigated at higher temperatures.

SnSe2-based devices have emerged as promising candidates for photodetection applications due to their unique optoelectronic properties. As a member of the IVA-VIA group, SnSe2 offers a combination of direct, indirect and forbidden transitions on its optical absorption edge, making it ideal for optoelectronic applications. In this study, SnSe2 exhibits excellent conductivity, reaching a maximum current of 8.83 mu A at 100 mV, and a field-effect mobility similar to 4 cm(2) V-1 s(-1) at room temperature and pressure. Photoresponse analysis revealed a significant increase in drain current during illumination with a white laser, along with persistent photoconductivity. The photocurrent was found to be strongly dependent on the gate voltage, with more pronounced effects observed at negative gate. Analysis of the characteristic times during the excitation and relaxation phases identified two distinct mechanisms: faster indirect band-to-band transitions and slower photoexcitation from intrinsic and extrinsic trap states due to adsorbates or interfacial defects. Times of approximately 1 second, independent of gate voltage, were observed for faster transitions. These results highlight SnSe2's potential for advanced optoelectronic applications, demonstrating its distinct photo-response behavior and sensitivity to gate voltage modulation.

2D material inks have the potential to strongly impact printed electronics, offering exciting opportunities for flexible and wearable devices. However, their electrical performance is often hindered by the resistive nature of inter‐nanosheet junctions within randomly assembled nanosheet networks, limiting their efficiency compared to individual nanosheets. Overcoming this challenge necessitates a comprehensive understanding of the conduction mechanisms governing charge transport in these networks. In this study, a water‐based graphene ink is prepared via liquid‐phase exfoliation (LPE), deposited onto Si/SiO₂ substrates through inkjet printing, and electrically characterized over a wide temperature range (80–400 K) following thermal annealing at different temperatures. To interpret the temperature‐dependent conductivity, a Random Resistor Network (RRN) model is employed that accounts for spatial and energetic variability among nodes. With this approach low and high temperature transport regimes are effectively studied, identifying inter‐flake and intra‐flake hopping mechanisms and providing valuable insights into the factors governing charge transport. Using Monte Carlo simulations, the RRN model delivers statistically robust predictions while capturing temperature‐dependent transitions and annealing effects, achieving excellent agreement with experimental observations.

Recent interest in flexible sensors, fueled by their affordability, wearability, lightweight design, and ease of fabrication, has driven advancements in applications and fundamental understanding. Herein, we explore the synthesis route of the three-dimensional (3D) graphene-coated sponges and investigate their mechanical and electronic transport properties. Tensile and compression tests on the graphene coated sponges demonstrate Young's modulus of around 0.075 MPa. Electrical measurements with ohmic contacts show DC conductivity as low as 0.5 S/cm. Bonding durability and wettability tests under water immersion and ultrasonic agitation confirmed the strong adhesion and enhanced hydrophobicity of the graphene coating, demonstrating its mechanical and chemical robustness. Temperature measurements reveal a non-monotonic behavior in the sponge's resistance as the temperature decreases. The resistance exhibits a pronounced peak around 250 K as the temperature drops from 295 K to 200 K, followed by a steady increase from 200 K to 77 K. Field emission measurements show a stable current and a reduction in turn-on voltage as the spacing between the anode and the emitting surface decreases, revealing a low turn-on voltage of about 13 V and a field enhancement factor of 286 at an anode-cathode distance of 300 nm. Experimental data are analyzed using the Fowler-Nordheim model, evidencing a non-monotonic dependence of the field enhancement factor on the cathode-anode separation distance in the range of 100-500 nm. The results show that such a flexible 3D graphene coated sponge can be utilized as a sensitive thermistor, a field emitter, and a pressure sensor.

As artificial intelligence continues to evolve, neuromorphic technologies, which emulate biological neural networks, are increasingly seen as a promising direction. Two-dimensional materials are considered promising for neuromorphic applications due to their tunable electrical and optoelectronic properties. In this work, a back-gated tin disulfide (SnS2) field-effect transistor (FET) is electrically and optoelectronically characterized at different temperatures (80, 295, and 380 K), pressures (ambient and 10-4 mbar), and illumination conditions (dark and laser light from 420 to 800 nm). Responsivity peaks of up to ∼100 A/W are recorded. Persistent photoconductivity is observed, with current retention after illumination ranging from 0% to ∼30% of the initial dark current, depending on temperature and gate voltage. The underlying microscopic mechanisms are analyzed, revealing a key role for trap states and ambient adsorbates, and a qualitative model is proposed to explain the observed effects. Trap states within the bandgap, often considered detrimental, are exploited to induce synaptic plasticity, with synaptic weight changes tunable from 0.001 to 3000. Temperature and gate voltage are found to be effective parameters for modulating plasticity, enabling smooth transitions between short-term and long-term behavior. These results clarify the microscopic origin of plasticity in SnS2, demonstrate its robustness under realistic conditions, and lay the foundation for the integration of this two-dimensional material into next-generation neuromorphic architectures.

InAs nanowire-based back-gated field-effect transistors realized starting from individual InAs nanowires are investigated at different temperatures and as building blocks of inverter circuits for logic applications. The nanodevices show n-type behavior with a carrier concentration up to 8.0 x 1017 cm-3 and corresponding electron mobility exceeding 1590 and 1940 cm2 V-1 s-1 at room temperature and 200 K, respectively. The investigation over a wide temperature range indicates no Schottky barrier at source/drain electrodes, where Ohmic contacts are formed with the Cr adhesion layer. The switching characteristics of the devices improve with decreasing temperature and a subthreshold swing less than 1 V/decade is achieved at 200 K, suggesting the occurrence of a trap population with density around 4 x 108 cm-1 eV-1. Besides, the nanodevices are exploited in single-transistor circuits with a resistive load. As an inverter, the circuit shows 30 % and 24 % of the voltage supply noise margins for the high and low states, respectively; as a low signal amplifier, it shows a gain that is weakly dependent on temperature. The present study highlights the impact of temperature on the operation of InAs nanowire-based back-gated transistors and evidences their potential applications in logic circuits including inverters and low-signal amplifiers.

The field emission properties of rhenium diselenide (ReSe2) nanosheets on Si/SiO2 substrates, obtained through mechanical exfoliation, have been investigated. The n-type conduction was confirmed by using nano-manipulated tungsten probes inside a scanning electrode microscope to directly contact the ReSe2 flake in back-gated field effect transistor configuration, avoiding any lithographic process. By performing a finite element electrostatic simulation of the electric field, it is demonstrated that the use of a tungsten probe as anode, at a controlled distance from the ReSe2 emitter surface, allows the collection of emitted electrons from a reduced area that furtherly decreases by reducing the tip-sample distance, i.e. allowing a local characterization of the field emission properties. Experimentally, it is shown that the turn-on voltage can be linearly reduced by reducing the cathode-anode separation distance. By comparing the measured current-voltage characteristics with the numerical simulations, it is also shown that the effective field enhancement on the emitter surface is larger than expected because of surface defects. Finally, it is confirmed that ReSe2 nanosheets are suitable field emitters with high time stability and low current fluctuations.

Iontronics exploits mobile ions within electrolytes to control the electronic properties of materials and devices' electrical and optical response. In this frame, ionic liquids are widely exploited for the gating of semiconducting nanostructure devices, offering superior performance compared to conventional dielectric gating. In this work, we engineer ionic liquid gated InAs nanowire-based field effect transistors and adopt the set-and-freeze dual gate device operation to probe the nanowires in several ionic gate regimes. We exploit standard back-gating at 150 K, when the ionic liquid is frozen and any crosstalk between the ionic gate and the back gate is ruled out. We demonstrate that the liquid gate polarization has a persistent effect on the nanowire properties. This effect can be conveniently exploited to fine-tune the properties of the nanowires and enable new device functionalities. Specifically, we correlate the modification of the ionic environment around the nanowire to the transistor threshold voltage and hysteresis, on/off ratio and current level retention times. Based on this, we demonstrate memory operations of the nanowire field effect transistors. Our work shines a new light on the interaction between electrolytes and semiconducting nanostructures, providing useful insights for future applications of nanodevice iontronics.

We investigate the field emission properties of tetrapod-shaped zinc oxide (ZnO) micro and nanostructures prepared using a flame transport synthesis approach. Using a piezo-driven metallic tip as an anode, we performed a local characterization from the apex of a tetrapod arm, where the effective emitting area was limited below 1 mu m2. This configuration allows extremely low turn-on voltages, of 7 V, and a field enhancement factor of 70 at an anode-cathode distance of 600 nm. The experimental data were analyzed using the Fowler-Nordheim model, evidencing a non-monotonous dependence of the turn-on field and the field enhancement factor on the cathode-anode separation distance in the range of 100-900 nm. The ZnO tetrapods demonstrated good current stability, highlighting their potential for high-performance, low-consumption electron-emitting devices with very low turn-on voltage.

Lanthanides are largely used in optoelectronics as dopants to enhance the physical and optical properties of semiconducting devices. In this study, lanthanum(III)hydroxide nanoparticles (La(OH)3NPs) are used as a dopant of polyethylenimine (PEI)-functionalized nitrogen (N)-doped graphene quantum dots (PEI-NGQDs). The La(OH)3NPs-dopedPEI-NGQDs nanocomposites are prepared from La(NO)3 in a single step by a green novel method and are characterized by Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Deposited over an n-type Si wafer, the La(OH)3NPs-dopedPEI-NGQDs nanocomposites form Schottky diodes. The I-V characteristics and the photoresponse of the diodes are investigated as a function of the illumination intensity in the range 0-110 mW cm-2 and at room temperature. It is found that the rectification ratio and ideality factor of the diode decrease, while the Schottky barrier and series resistance increase with the enhancing illuminations. As a photodetector, the La(OH)3NPs-dopedPEI-NGQDs/n-Si heterojunction exhibits an appreciable responsivity of 3.9 × 10-3 AW-1 under 22 mW cm-2 at -0.3 V bias and a maximum detectivity of 8.7 × 108 Jones under 22 mW cm-2 at -0.5 V. This study introduces the green synthesis and presents the structural, electrical, and optoelectronic properties of La(OH)3NPs-dopedPEI-NGQDs, demonstrating that these nanocomposites can be promising for optoelectronic applications.