Modern short-scale information transmission mainly relies on dissipative charge transport, with electrons scattered by defects and phonons, leading to significant power losses. By contrast, excitons-charge-neutral quasiparticles-offer a playground for electro-optical energy-efficient information transduction and processing owing to their extended lifetimes, charge neutrality and efficient electrostatic control. In this work, we report the observation of fast exciton transport in a van der Waals heterostructure over distances exceeding 10 µm, constrained only by the heterostructure finite size. We observe the presence of excitonic potential ramps that leads to long-range rapid exciton drift and enables rapid dilution of the initial exciton population. Our measurements reveal fast exciton propagation, with interlayer exciton drift velocities of approximately 2.66 × 104 m s-1, within a transport regime that remains robust across a wide range of exciton densities and temperatures up to 150 K. Our work opens avenues for the development of high-speed, energy-efficient excitonic devices, such as field-effect switches and modulators.

The past decade has seen rapid growth in the number of experimentally realized two-dimensional (2D) materials with diverse chemical and physical properties. However, information on their crystal structure, synthesis routes, and measured or predicted properties remains scattered across thousands of publications. Here, we consolidate this fragmented knowledge by establishing X2DB─an open infrastructure that integrates experimental and computational data on 2D materials. Using extensive literature mining and direct community uploads, we identify 370 unique 2D materials that have been realized in monolayer or few-layer form and link them to their digital counterparts in computational databases, enabling consistent ab initio characterization of their properties across monolayer, bilayer, and bulk forms. We describe the structure and content of the database, highlight its support for community uploads, illustrate how it can be used to generate scientific insight, and introduce a hierarchical classification of the known set of 2D materials. Our work supports the integration and cross-fertilization of experimental and theoretical knowledge and contributes to data-driven and predictive synthesis of 2D materials.

The performance of transistors based on two-dimensional transition metal dichalcogenide semiconductors is restricted by the poor interface quality between two-dimensional materials and conventional three-dimensional contacts. Transition-metal-dichalcogenide-based metal–semiconductor heterostructures have been developed to enhance device performance, but finding fabrication techniques that combine high-quality growth with scalability and broad applicability remains a challenge. Here we show that a method that combines metal–organic chemical vapour deposition and sulfurization can be used to create patterned heterostructures of niobium disulfide and molybdenum disulfide at the wafer scale. The niobium disulfide–molybdenum disulfide heterostructures can be used as the active channel material of field-effect transistors and non-volatile memory devices. Compared with pristine molybdenum disulfide, the heterostructures exhibit up to nine times higher on current due to a reduced contact resistance, a maximum effective mobility of 77 cm2 V−1 s−1 and a 95.8% yield (of 144 field-effect transistors). Furthermore, our floating-gate field-effect transistors show a large programming window, precise and continuous conductance modulation, endurance over 60,000 programming pulses and an estimated retention time of around 19 years. Device simulation shows that the large programming window of the long-channel devices (around 14 V) can be maintained at scaled gate lengths below 100 nm with proper control oxide scaling. Patterned and scalable two-dimensional metal–semiconductor heterostructures formed between niobium disulfide and molybdenum disulfide can be created using an in situ sulfurization process and used to make field-effect transistors and non-volatile memory devices.

Strain is a proven technique for modifying the bandgap and enhancing carrier mobility in 2D materials. Most current strain engineering techniques rely on the post-growth transfer of these atomically thin materials from growth substrates to target surfaces, limiting their integration into nanoelectronics. Here, we present a new approach where strain in 2D materials is already introduced directly during their growth on grayscale-patterned topographies instead of flat surfaces. Both strain levels and orientations are deterministically engineered by controlling grayscale surface contour lengths through thermal expansion mismatches in nanostructured stacks, where the conformally grown and firmly attached 2D material is forced to match the underlying morphology change during cooling. With this method, we experimentally demonstrate precise control of localized tensile strain from 0 to 0.5% in grown MoS2 monolayer along both uni- and multiaxial directions, while higher strain levels are shown to be theoretically possible. This strain-engineered growth of 2D material films directly on the target substrates is a generic and adaptable approach to various combinations of grayscale-thin-film/substrates and eliminates all the transfer-related limitations of previous approaches, thus paving the way for integrating strained 2D materials into next-generation nanoelectronics.

Spin defects in two-dimensional materials hold significant potential for quantum information technologies and sensing applications. The negatively charged boron vacancy (VB-) in hexagonal boron nitride (hBN) has attracted considerable attention as a quantum sensor due to its demonstrated sensitivity to temperature, magnetic fields, and pressure.1 However, its applications have thus far been limited by inherently dim photoluminescence (PL). By fabricating a van der Waals heterostructure with a sensitizing donor layer, lead iodide (PbI2), we effectively enhance the PL intensity from the VB- by 5-45x, while maintaining compatibility with other heterostructures and vdW optoelectronic platforms. The type-I band alignment at the heterojunction enables efficient exciton migration while suppressing back-electron transfer, and the strong spectral overlap between the PbI2 emission and defect absorption supports efficient fluorescence resonance energy transfer. Ab initio density functional theory (DFT) predicts a photon-ratcheting mechanism that boosts absorption and emission while maintaining magnetic resonance (ODMR) contrast through minimal hybridization. Experimentally, the heterostructure exhibits enhanced continuous-wave ODMR sensitivity and functions as a precise probe of external magnetic fields. This work establishes a proof-of-concept for amplifying weak defect signals in nanomaterials, highlighting a new strategy for engineering their optical and magnetic responses.

Optical microcavities provide a powerful and versatile framework for manipulating the dynamics of photonic emission from optically active materials through light recirculation. Spatially indirect interlayer excitons (IXs) exhibit broad tunability of their emission energy via the quantum-confined Stark effect. However, the electrical tunability of IXs has not been exploited in cavity-coupled systems until now. Here we modulate the detuning between the cavity resonance and the IX emission in a monolithic Fabry-Perot cavity using an applied vertical electric field. We reveal a simultaneous enhancement of both the emission intensity and lifetime of weakly coupled IXs when in resonance with the optical cavity owing to strong Purcell inhibition and cavity transparency effects. We further investigate the tunable momentum dispersion of coupled IXs through back-focal-plane imaging and explain our results by the cavity coupling of IX transition dipoles as supported by theoretical modelling. Our work demonstrates an integration effort enabling the versatile tuning of highly interacting IXs within monolithic cavities, revealing the attractiveness of electrically tunable IX cavity coupling for both fundamental studies towards exciton condensate manipulation and future integration of excitonic devices.

Extended efforts have been devoted to the study of strongly-interacting excitons and their dynamics, towards macroscopic quantum states of matter such as Bose-Einstein condensates of excitons and polaritons. Momentum-direct layer-hybridized excitons in transition metal dichalcogenides have attracted considerable attention due to their high oscillator strength and dipolar nature. However, the tunability of their interactions and dynamics remains unexplored. Here, we achieve an unprecedented control over the nonlinear properties of dipolar layer-hybridized excitons in an electrically gated van der Waals homobilayer monitored by transient optical spectroscopy. By applying a vertical electric field, we reveal strong Coulomb interactions of dipolar hybrid excitons, leading to opposite density-dependent energy shifts of the two main hybrid species based on their dipolar orientation, together with a strongly enhanced optical saturation of their absorption. Furthermore, by electrically tuning the interlayer tunneling between the hybridized carriers, we significantly extend the formation time of hybrid excitons, while simultaneously increasing their decay times. Our findings have implications for the search on quantum blockade and condensation of excitons and dipolaritons in two-dimensional materials.

Since the discovery of graphene in 2004, there has been rapid progress in research on two-dimensional (2D) material’s potential applications with significant impact. Efforts to bring 2D materials closer to industrial production, quality assessment, and standardization still need to be expanded upon. This remains challenging because sophisticated analytics techniques are required to analyze a limited amount of material with high variability due to differences in the synthesis process and the lack of a clear standard for comparing results. Modern methods can evaluate domain size, surface coverage, defects, dopants, mobility, and photoluminescence parameters. Still, it is challenging to understand the structure–property relationship due to external influences such as adsorbates and strain, which can alter results. To address this problem, the Graphene Flagship project conducted an extensive benchmarking study of monolayer molybdenum disulfide grown through chemical vapor deposition by various groups. The study employed a variety of techniques to characterize the material, including optical and transmission electron microscopy, Raman spectroscopy, photoluminescence, X-ray photoelectron spectroscopy, and capacitance-voltage measurements. Herein, we present the results of this comprehensive study and the correlation between various methods

Metallic two-dimensional (2D) transition metal dichalcogenides (TMDCs) are garnering significant attention for their ability to enhance device performance when used as 2D contacts with semiconducting 2D materials, as well as for their intriguing low-temperature properties, including superconductivity, magnetism, and charge density waves (CDWs). However, the advancement of both fundamental studies and practical applications has been hindered by challenges in synthesizing high-quality, large-area materials. In this work, we report the epitaxial growth of wafer-scale 2D superconducting TMDC single-crystal multilayers by metal–organic chemical vapor deposition (MOCVD). Our NbS2 multilayer films achieve high wafer-scale uniformity and single crystallinity of 2H phase, as confirmed by AFM, Raman spectroscopy, SHG mapping, LEED and STEM measurements. This is enabled by a dual-precursor strategy that drives self-templated concurrent epitaxy on lattice-matched sapphire, which is further supported by a kinetic growth model. Devices fabricated from the NbS2 film demonstrate superconductivity below a transition temperature of 3 K, consistent with a Berezinskii-Kosterlitz-Thouless (BKT) type superconducting phase transition, with an impressive yield of 95.1

This paper presents a novel nanoscale platform based on vanadium dioxide (VO2) two-terminal devices shaped like nanowires (NWs). For the first time we report CMOS compatible VO2 two-terminal devices with little-to-no stochasticity in the absence of electroforming phenomenon, as well as partially suspended stochastic nanostructures. Characterization for varying NWs number and contact distance offers an overview on possible designs with predictable switching behavior. Importantly, we report proof-of-concept optical sensing for both types of nanostructures, highlighting the compromise between stochasticity and performance for future optical sensors based on nanostructured VO2.

Chirality, a basic property of symmetry breaking, is crucial for fields such as biology and physics. Recent advances in the study of chiral systems have stimulated interest in the discovery of symmetry-breaking states that enable exotic phenomena such as spontaneous gyrotropic order and superconductivity. Here we examine the interaction between light chirality and electron spins in indium selenide and study the effect of magnetic field on emerging tunnelling photocurrents at the Van Hove singularity. Although the effect is symmetric under linearly polarized light excitation, a non-symmetric signal emerges when the excitation is circularly polarized, making it possible to electrically detect light’s chirality. Our study shows a negligible out-of-plane g-factor for few-layer indium selenide at the valence band edge, resulting in an unbalanced Zeeman splitting in hexagonal boron nitride spin bands. This finding allows us to measure the change in energy barrier height with exceptional resolution ( 15 μeV). Furthermore, we confirm the long-standing theoretical prediction of spin-polarized hole accumulation in the flat valence band at increasing laser powers. Light chirality and electron spin interactions and the dependence of tunnelling photocurrent on the magnetic field are studied in indium selenide, exploiting its non-symmetric response to circularly polarized light to electrically detect chirality.

Monolayers of transition-metal dichalcogenides, such as MoS2, have attracted significant attention for their exceptional electronic and optical properties, positioning them as ideal candidates for advanced optoelectronic applications. Despite their strong excitonic effects, the atomic-scale thickness of these materials limits their light absorption efficiency, necessitating innovative strategies to enhance light-matter interactions. Plasmonic nanostructures offer a promising solution to overcome those challenges by amplifying the electromagnetic field and also introducing other mechanisms, such as hot electron injection. In this study, we investigate the vibrational and optical properties of MoS2 monolayer deposited on gold substrates and gratings, emphasizing the role of strain and plasmonic effects using conventional spectroscopic techniques. Our results reveal significant biaxial strain in the supported regions and a uniaxial strain gradient in the suspended ones, showing a strain-induced exciton and carrier funneling effect toward the center of the nanogaps. Moreover, we observed an additional polarization-dependent doping mechanism in the suspended regions. This effect was attributed to localized surface plasmons generated within the slits, as confirmed by numerical simulations, which may decay nonradiatively into hot electrons and be injected into the monolayer. Photoluminescence measurements further demonstrated a polarization-dependent trion-to-A exciton intensity ratio, supporting the hypothesis of additional plasmon-induced doping. These findings provide a comprehensive understanding of the strain-mediated funneling effects and plasmonic interactions in hybrid MoS2/Au nanostructures, offering valuable insights for developing high-efficiency photonic devices and quantum technologies, including polarization-sensitive detectors and excitonic circuits.

The alloying of two-dimensional (2D) transition metal dichalcogenides (TMDs) is an established route to produce robust semiconductors with continuously tunable optoelectronic properties. However, typically reported methods for fabricating alloyed 2D TMD nanosheets are not suitable for the inexpensive, scalable production of large-area (m2) devices. Herein we describe a general method to afford large quantities of compositionally-tunable 2D TMD nanosheets using commercially available powders and liquid-phase exfoliation. Beginning with Mo(1-x)WxS(2) nanosheets, we demonstrate tunable optoelectronic properties as a function of composition. We extend this method to produce Mo0.5W0.5Se2 MoSSe, WSSe, and quaternary Mo0.5W0.5SSe nanosheets. High-resolution scanning transmission electron microscopy (STEM) imaging confirms the atomic arrangement of the nanosheets, while an array of spectroscopic techniques is used to characterize the chemical and optoelectronic properties. This transversal method represents an important step towards upscaling tailored TMD nanosheets with a broad range of tunable optoelectronic properties for large-area devices.

Intensive research has been carried out on two-dimensional materials, in particular molybdenum disulfide, towards high-performance field effect transistors for integrated circuits1. Fabricating transistors with ohmic contacts is a challenging task due to the formation of a high Schottky barrier that severely limits the performance of the transistors for real-world applications. Graphene-based heterostructures can be used in addition to, or as a substitute for unsuitable metals. In this paper, we present lateral heterostructure transistors made of scalable chemical vapor-deposited molybdenum disulfide and chemical vapor-deposited graphene achieving a low contact resistances of about 9 kΩ·µm and high on/off current ratios of 108. Furthermore, we also present a theoretical model calibrated on our experiments showing further potential for scaling transistors and contact areas into the few nanometers range and the possibility of a substantial performance enhancement by means of layer optimizations that would make transistors promising for use in future logic integrated circuits.

While most neuromorphic systems are based on nanoscale electronic devices, nature relies on ions for energy-efficient information processing. Therefore, finding memristive nanofluidic devices is a milestone toward realizing electrolytic computers mimicking the brain down to its basic principles of operation. Here, we present a nanofluidic device designed for circuit scale in-memory processing that combines single-digit nanometric confinement and large entrance asymmetry. Our fabrication process is scalable while the device operates at the second timescale with a conductance ratio in the range 10-60. In-operando optical microscopy unveils the origin of memory, arising from the reversible formation of liquid blisters modulating the device conductance. The combination of features of these mechano-ionic memristive switches permits assembling logic circuits composed of two interactive devices and an ohmic resistor. These results open the way to design multi-component ionic machinery, such as nanofluidic neural networks, and implementing brain-inspired ionic computations.

Grayscale structured surfaces with nanometer-scale features are used in a growing number of applications in optics and fluidics. Thermal scanning probe lithography achieves a lateral resolution below 10 nm and a vertical resolution below 1 nm, but its maximum depth in polymers is limited. Here, we present an innovative combination of nanowriting in thermal resist and plasma dry etching with substrate cooling, which achieves up to 10-fold amplification of polymer nanopatterns into SiO2 without proportionally increasing surface roughness. Sinusoidal nanopatterns in SiO2 with 400 nm pitch and 150 nm depth are fabricated free of shape distortion after dry etching. To exemplify the possible applications of the proposed method, grayscale dielectric nanostructures are used for scalable manufacturing through nanoimprint lithography and for strain nanoengineering of 2D materials. Such a method for aspect ratio amplification and smooth grayscale nanopatterning has the potential to find application in the fabrication of photonic and nanoelectronic devices.

The Nernst effect, a transverse thermoelectric phenomenon, has attracted significant attention for its potential in energy conversion, thermoelectrics and spintronics. However, achieving high performance and versatility at low temperatures remains elusive. Here we demonstrate a large and electrically tunable Nernst effect by combining the electrical properties of graphene with the semiconducting characteristics of indium selenide in a field-effect geometry. Our results establish a new platform for exploring and manipulating this thermoelectric effect, showcasing the first electrical tunability with an on/off ratio of 103. Moreover, photovoltage measurements reveal a stronger photo-Nernst signal in the graphene/indium selenide heterostructure compared with individual components. Remarkably, we observe a record-high Nernst coefficient of 66.4 μV K-1 T-1 at ultralow temperatures and low magnetic fields, an important step towards applications in quantum information and low-temperature emergent phenomena.

Adapting electronics to perfectly conform to nonplanar and rough surfaces, such as human skin, is a challenging task, which could open up new applications in fields of high economic and scientific interest, ranging from health to robotics, human-machine interface, and Internet of Things. The key to success lies in defining a technology that can lead to ultrathin devices, exploiting ultimately thin materials, with high mechanical flexibility and excellent electrical properties. Here, we report a hybrid approach for the development of high-performance, ultrathin and conformable electronic devices, based on the integration of semiconducting transition metal dichalcogenides, i.e., MoS2, with organic gate dielectric material, i.e., polyvinyl formal (PVF) combined with inkjet printed PEDOT:PSS electrodes. Through this novel approach, transistors and simple digital and analogue circuits are fabricated by a sequential stacking of ultrathin (nanometer) layers on a few micrometers thick polyimide substrate, which guarantees the high flexibility mandatory for the targeted applications.

Field-effect transistors (FETs) based on two-dimensional materials (2DMs) with atomically thin channels have emerged as a promising platform for beyond-silicon electronics. However, low carrier mobility in 2DM transistors driven by phonon scattering, remains a critical challenge. To address this issue, we propose the controlled introduction of localized biaxial tensile strain as an effective mean to inhibit electron-phonon scattering in 2DM. Strain is achieved by conformally adhering the 2DM via van-der-Waals forces to a dielectric layer previously nanoengineered with a gray-tone topography. Our results show that a monolayer MoS2 FETs under tensile strain achieves an 8-fold increase in on-state current reaching mobilities of 185 cm2/Vs at room temperature, in good agreement with theoretical calculations. The present work on nanotopographic grayscale surface engineering and the use of high-quality dielectric materials has the potential to find application in the nanofabrication of photonic and nanoelectronic devices.

van der Waals heterostructures of two-dimensional materials have unveiled frontiers in condensed matter physics, unlocking unexplored possibilities in electronic and photonic device applications. However, the investigation of wide-gap, high-κ layered dielectrics for devices based on van der Waals structures has been relatively limited. In this work, we demonstrate an easily reproducible synthesis method for the rare-earth oxyhalide LaOBr, and we exfoliate it as a 2D layered material with a measured static dielectric constant of 9 and a wide bandgap of 5.3 eV. Furthermore, our research demonstrates that LaOBr can be used as a high-κ dielectric in van der Waals field-effect transistors with high performance and low interface defect concentrations. Additionally, it proves to be an attractive choice for electrical gating in excitonic devices based on 2D materials. Our work demonstrates the versatile realization and functionality of 2D systems with wide-gap and high-κ van der Waals dielectric environments.