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A hybrid SnP2S6/(PEA)2PbI4 photodetector with high responsivity and fast response time is developed, which is promising for multiple optoelectronic applications.

The demand for advanced safeguards has increased with a rise in terrorism and international conflicts. Traditional impact-resistant glass and ceramics have relatively high performance but have several drawbacks as well, such as inflexibility, heaviness, and high processing energy consumption. Herein, we propose sustainable lignocellulosic duplicates: the

ABSTACT In-plane anisotropy (IPA) due to asymmetry in lattice structures provides an additional parameter for the precise tuning of characteristic polarization-dependent properties in two-dimensional (2D) materials, but the narrow range within which such method can modulate properties hinders significant development of related devices. Herein we present a novel periodic phase engineering strategy that can remarkably enhance the intrinsic IPA obtainable from minor variations in asymmetric structures. By introducing alternant monoclinic and rutile phases in 2D VO2 single crystals through the regulation of interfacial thermal strain, the IPA in electrical conductivity can be reversibly modulated in a range spanning two orders of magnitude, reaching an unprecedented IPA of 113. Such an intriguing local phase engineering in 2D materials can be well depicted and predicted by a theoretical model consisting of phase transformation, thermal expansion, and friction force at the interface, creating a framework applicable to other 2D materials. Ultimately, the considerable adjustability and reversibility of the presented strategy provide opportunities for future polarization-dependent photoelectric and optoelectronic devices.

Metallic lithium is considered as the ultimate anode material for lithium-based batteries due to its highest energy density. However, as an anode, commercial Li metal foils are too thick, with a large amount of trouble to balance its exorbitant areal capacity with common cathodes in full cells. Here, a new chemical thinning strategy is proposed via a simple surface dissolving reaction between lithium and naphthalene, which enables scalable, continuous, and roll-to-roll preparation of ultrathin Li foil. A Li foil less than 15 μm with a clean surface can be successfully obtained within 20 min. The thinning rate and thickness of the lithium foil can be easily adjusted by changing the concentration, temperature, and operation mode. The produced Li-Naph solution after thinning can also be used as a multifunctional reagent of great value, and the Li ions in the final waste solution can be further extracted in the form of Li

Graphitic carbon nitride is introduced to the PEO-based solid polymer electrolyte as a mediator to stabilize the interface to a lithium metal anode.

We modify Zn anodes with island-distributed indium (Zn@In). The effective suppression of hydrogen evolution by Zn@In enables an ultra-dense and rock-like Zn plating morphology, extending the cycling life of a Zn symmetrical cell to over one year.

Strong intermolecular interactions in 2D organic molecular crystals arising from π-π stacking have been widely explored to achieve high thermal stability, high carrier mobility, and novel physical properties, which have already produced phenomenal progress. However, strong intermolecular interactions in 2D inorganic molecular crystals (2DIMCs) have rarely been investigated, severely limiting both the fundamental research in molecular physics and the potential applications of 2DIMCs for optoelectronics. Here, the effect of strong intermolecular interactions induced by unique short intermolecular Se-Se and P-Se contacts in 2D α-P4Se3 nanoflakes is reported. On the basis of theoretical calculations of the charge density distribution and an analysis of the thermal expansion and plastic-crystal transition, the physical picture of strong intermolecular interactions can be elucidated as a higher charge density between adjacent P4Se3 molecules, arising from an orderly and close packing of P4Se3 molecules. More importantly, encouraged by the strong intermolecular coupling, the in-plane mobility of α-P4Se3 nanoflakes is first calculated with a quantum nuclear tunneling model, and a competitive hole mobility of 0.4 cm2 V-1 s-1 is obtained. Our work sheds new light on the intermolecular interactions in 2D inorganic molecular crystals and is highly significant for promoting the development of molecular physics and optoelectronics.

Atomically thin two‐dimensional (2D) bismuth oxychalcogenides (Bi2O2X, X = S, Se, Te) have recently attracted extensive attention in the material research community due to their unique structure, outstanding long‐term ambient stability, and high carrier mobility, which enable them as promising candidates for high‐performance electronic and optoelectronic applications. Herein, we present a comprehensive review on the recent advances of 2D bismuth oxychalcogenides research. We start with an introduction of their fundamental properties including crystal structure and electronic band structure. Next, we summarize the common techniques for synthesizing these 2D structures with high crystallinity and large lateral size. Furthermore, we elaborate on their device applications including transistors, artificial synapses, optical switch and photodetectors. The last but not the least, we summarize the existing challenges and prospects for this emerging 2D bismuth oxychalcogenides field.

Developing large capacity electrode with fast charging capability has always been our goal for high-energy Li-ion batteries. To design a superior electrode, large enough capacity, suitable voltage plateau and good ionic/electronic conductivity need to be taken into account at the same time. Herein, by fusing the semiconductor Ge into nonmetal P, a novel metallic GexP60-x solid solution with wide range tuneable region is proposed, which is proved a kind of Ge-P binary alloy instead of typical ionic/covalent compound. The synthesized GexP60-x is not a metal phophide, which is in contradictory to our conventional view. Attributed from its unique phosphorus-like layered structure, those GexP60-x alloys possess a high conductivity (∼2.4 × 106 S/m). More specially, the Ge-P interaction is not a strong covalent bond like metal phosphides and thereby, the conversion reaction process based on chemical bond breaking in metal phosphides would not take place in those GexP60-x alloys, being replaced by alloying-type mechanism only. Therefore, such GexP60-x alloys are the first ones which can simultaneously exhibit both large capacity (>1800 mAh/g), unexpected high reversibility (ICE>90%) and suitable voltage plateau (∼0.5 V), delivering 770 mAh/g within 15 min with low yet safe voltage for fast-charging battery. This discovery that nonmetallic and semiconductor elements can form conductive alloys based on solid solution chemistry injects fresh blood into high-performanced anode families and offers a new strategy for material design toward advanced fast charging electrodes for energy storage.

The unique intermolecular van der Waals force in emerging two-dimensional inorganic molecular crystals (2DIMCs) endows them with highly tunable structures and properties upon applying external stimuli. Using high pressure to modulate the intermolecular bonding, here we reveal the highly tunable charge transport behavior in 2DIMCs for the first time, from an insulator to a semiconductor. As pressure increases, 2D α-Sb2O3 molecular crystal undergoes three isostructural transitions, and the intermolecular bonding enhances gradually, which results in a considerably decreased bandgap by 25% and a greatly enhanced charge transport. Impressively, the in-situ resistivity measurement of the α-Sb2O3 flake shows a sharp drop by 5 orders of magnitude in 0 - 3.2 GPa. This work sheds new light on the manipulation of charge transport in 2DIMCs and is of great significance for promoting the fundamental understanding and potential applications of 2DIMCs in advanced modern technologies.

As the newly developed wide-bandgap semiconductors, two-dimensional layered metal phosphorus chalcogenides (2D LMPCs) exhibit enormous potential applications in ultraviolet (UV) photodetection due to their superior optoelectronic performance. However, 2D LMPC-based UV photodetectors generally suffer from low responsivity and slow response speed, which hinder their practical applications. Here, we present an effective strategy of sensitizing 2D LMPC UV photodetectors with a 2D Ruddlesden-Popper (RP) perovskite to enable high responsivity and fast response speed. As a demonstration, a hybrid heterojunction composed of RP perovskite (PEA)

Photodetectors operating in the shortwave infrared region are of great significance due to their extensive applications in both commercial and military fields. Narrowbandgap two-dimensional layered materials (2DLMs) are considered as the promising candidates for constructing next-generation high-performance infrared photodetectors. Nevertheless, the performance of 2DLMs-based photodetectors can hardly satisfy the requirements of practical applications due to their weak optical absorption. In the present study, a strategy was proposed to design high-performance shortwave infrared photodetectors by integrating metal-organic frameworks (MOFs) nanoparticles with excellent optical absorption characteristics and 2DLM with high mobility. Further, this study demonstrated the practicability of this strategy in a MOF/2DLM (Ni-CAT-1/Bi2Se3) hybrid heterojunction photodetector. Due to the transfer of photo-generated carriers from the MOF to Bi2Se3, the MOF nanoparticles integrated on the Bi2Se3 layer can increase the photocurrent by 2–3 orders of magnitude. The resulting photodetector presented a high responsivity of 4725 AW−1 and a superior detectivity of 3.5 × 1013 Jones at 1500 nm. The outstanding performance of the hybrid heterojunction arises from the synergistic function of the enhanced optical absorption and photogating effect. In addition, the proposed device construction strategy combining MOF photosensitive materials with 2DLMs shows a high potential for the future high-performance shortwave infrared photodetectors.

Bimetallic sulfides are expected to realize efficient CO2 electroreduction into formate over a wide potential window, however, will undergo in situ structural evolution under the reaction conditions. Therefore, clarifying the structural evolution process, the real active site and the catalytic mechanism appear significance. Here, taking Cu2SnS3 as an example, we unveiled that Cu2SnS3 occurred self-adapted phase separation toward forming the stable SnO2@CuS and SnO2@Cu2O heterojunction during the electrochemical process. Theoretical calculations illustrated that the strongly coupled interfaces as real active sites driven the electron self-flow from Sn4+ to Cu+, thereby promoting the delocalized Sn sites to combine HCOO* with H*. Cu2SnS3 nanosheets achieve over 83.4% formate selectivity in a wide potential range from -0.6 V to -1.1 V. Our findings provide insight into the structural evolution process and performance-enhanced origin of ternary sulfides under the CO2 electroreduction.

The mechanisms of Li deposition behaviors, which overwhelmingly affect battery performances and safety, are far to be understood in solid-state batteries. Here, using in situ micro-nano electrochemical scanning electron microscopy (SEM) manipulation platform, dynamic Li plating behaviors on 10 metallic substrates have been tracked, and the underlying mechanisms for dendrite-free Li plating are elucidated. Distinct Li deposition behaviors on Cu, Ti, Ni, Bi, Cr, In, Ag, Au, Pd, and Al are revealed quantitatively in nucleation densities, growth rates, and anisotropic ratios. For Li alloyable metals, the dynamic Li alloying process before Li growth is visually captured. It is concluded that a good affinity for Li and appropriate lattice compatibility between the substrate and Li are needed to facilitate homogeneous Li plating. Our work not only uncovers the Li plating dynamics, shedding light on the design of solid-state batteries, but also provides a powerful integrated SEM platform for future in-depth investigation of solid-state batteries.

Two-dimensional (2D) semiconductors have emerged both as an ideal platform for fundamental studies and as promising channel materials in beyond-silicon field-effect-transistors due to their outstanding electrical properties and exceptional tunability via external field. However, the lack of proper dielectrics for 2D semiconductors has become a major roadblock for their further development towards practical applications. The prominent issues between conventional 3D dielectrics and 2D semiconductors arise from the integration and interface quality, where defect states and imperfections lead to dramatic deterioration of device performance. In this review article, we will briefly analyze the root causes of such issues, summarize recent advances on some possible solutions, including various approaches of adapting conventional dielectrics to 2D semiconductors, and the development of novel dielectrics with van der Waals surface toward high-performance 2D electronics. Then, in the perspective, we will outline the requirements of ideal dielectrics for state-of-the-art 2D devices, and provide an outlook for their future development. This article is protected by copyright. All rights reserved.

Silicon semiconductor technology is approaching its downscaling limit in state-of-the-art electronics. Atomically thin two-dimensional (2D) semiconductors allow exceptional gate electrostatics in field-effect transistors (FETs), thus holding potential as the candidate channel materials beyond silicon. However, it remains challenging to integrate ultrathin and uniform high-κ dielectrics on 2D materials to fabricate FETs with large gate capacitances, though this is highly required to reduce the device operating voltage toward the energy-efficient electronics. Here we report a versatile two-step approach to integrating high-quality dielectric film with sub-1-nm equivalent oxide thickness (EOT) on 2D materials. Inorganic molecular crystal Sb2O3 is homogeneously deposited on 2D materials as a van der Waals buffer layer, which forms a high-quality oxide-to-semiconductor interface and offers a highly hydrophilic surface, enabling the integration of diverse high-κ dielectrics via atomic layer deposition. Using such an approach, we can fabricate monolayer molybdenum disulfide-based FETs with the ever-reported thinnest EOT (0.67 nm). The transistors exhibit an on/off ratio of over 106 using an ultralow operating voltage of 0.4 V, i.e., an unprecedentedly high gating efficiency not matched by any previous FETs. Our results may pave the way for the applications of 2D materials in the future low-power ultra-scaling electronic devices.

As a new class of solid electrolytes, halide solid electrolytes have the advantages of high ionic conductivity at room temperature, stability to high-voltage cathodes, and good deformability, but they generally show a problem of being unstable to a lithium anode. Here, we report the use of Li

Two-dimensional (2D) ternary materials have sprung up in a broad variety of optoelectronic applications due to their robust degree of freedom to design the physical properties of the materials through adjusting the stoichiometric ratio. However, the controlled growth of high-quality 2D ternary materials with good chemical stoichiometry remains challenging, which severely impedes their further development and future device applications. Herein, we synthesize ternary Bi2Te2Se (BTS) flakes with a thickness down to 4 nm and a lateral dimension about 60 μm by an atmospheric-pressure solid source thermal evaporation method on a mica substrate. The phonon vibration and electrical transportation of 2D BTS are respectively investigated by temperature-dependent Raman spectrum and conductivity measurements. Furthermore, the photodetector based on 2D BTS exhibits excellent performance with a high light on/off ratio of 1300 (365 nm), a wide spectral response range from 365 to 980 nm, and an ultra-fast response speed up to 2 μs. In addition, its electrical and photoelectric properties can be modulated by the gate voltage, offering an improved infrared responsivity to 2.74 A W−1 and an on/off ratio of 2266 under 980 nm. This work introduces an effective approach to obtain 2D BTS flakes and demonstrates their excellent prospects in optoelectronics.

Thin (≤20 μm) and free-standing Li metal foils would enable precise prelithiation of anode materials and high-energy-density Li batteries. Existing Li metal foils are too thick (typically 50 to 750 μm) or too mechanically fragile for these applications. Here, we developed a facile and scalable process for the synthesis of an ultrathin (0.5 to 20 μm), free-standing and mechanically robust Li metal foil within a graphene oxide host. In addition to low areal capacities of ~0.1 to 3.7 mAh cm−2, this Li foil also has a much-improved mechanical strength over conventional pure Li metal foil. Our Li foil can improve the initial Coulombic efficiency of graphite (93%) and silicon (79.4%) anodes to around 100% without generating excessive Li residue, and increases the capacity of Li-ion full cells by 8%. The cycle life of Li metal full cells is prolonged by nine times using this thin Li composite anode. Thin Li foils are desirable for high-energy Li battery applications. Here, Cui and team devise a fabrication route for ultrathin (less than 20 μm) Li foils that show promise for improving existing anodes including silicon, graphite and metallic Li.

Manipulating the catalyst-electrolyte interface to push reactants into the inner Helmholtz plane (IHP) is highly desirable for efficient electrocatalysts, however, it has rarely been implemented due to the elusive electrochemical IHP and inherent inert catalyst surface. Here, we propose the introduction of local force fields by the surface hydroxyl group to engineer the electrochemical microenvironment and enhance alkaline hydrogen evolution activity. Taking a hydroxyl group immobilized Ni/Ni

Activating basal plane inert sites will endow MoTe2 with prominent hydrogen evolution reaction (HER) catalytic capability and arouse a new family of HER catalysts. Herein, we fabricated single MoTe2 sheet electrocatalytic microdevice for in situ revealing the activated basal plane sites by vacancies introducing. Through the extraction of electrical parameters of single MoTe2 sheet, the in-plane and interlayer conductivities were optimized effectively by Te vacancies due to the defect levels. More deeply, Te vacancies can induce the delocalization of electrons around Mo atoms and shift the d-band center, as a consequence, facilitate the adsorption of H from the catalyst surface for HER catalysis. Benefiting by the coordinated regulation of band structure and local charge density, the overpotential at −10 mA·cm−2 was reduced to 0.32 V after Te vacancies compared to 0.41 V for the basal plane sites of same MoTe2 nanosheet. Meanwhile, the insights gained from single nanosheet electrocatalytic microdevice can be applied to the improved HER of the commercial MoTe2 power. That the in situ testing of the atomic structure-electrical behavior-electrochemical properties of a single nanosheet before/after vacancies introducing provides reliable insight to structure-activity relationships.

Manganese phosphorous selenium (MnPSe3), as a representative of layered metal phosphorus trichalcogenides (MPTs), has gained significant attention due to its direct bandgap, high carrier mobility, large absorption coefficient, which indicate great potential in photoelectric application. Herein, high-quality two-dimensional (2D) MnPSe3 flakes were mechanically exfoliated from the corresponding bulk crystals synthesized by chemical vapor transport (CVT) methods. The systematic investigation was applied to the lattice vibrations of MnPSe3via angle-resolved polarized Raman spectroscopy (ARPRS), and the Raman vibration modes were determined based on Raman selection rules and crystal symmetry. Impressively, the photodetectors based on 2D MnPSe3 flakes exhibit excellent photoresponse to the ultraviolet light with a responsivity up to 22.7 A W−1 and a detectivity of 2.4 × 1011 Jones. The high performance in the ultraviolet range signifies that 2D MnPSe3 is expected to be a powerful candidate for future ultraviolet photodetection.

Two-dimensional layered semiconductors have been the research focus of electronics and optoelectronics owing to their atomic thickness, light-matter interaction, and large-scale integration. Metal phosphorus trichalcogenides (MPTs), possessing the structure of [P2S6]4– or [P2Se6]4– surrounded with metal cations, have emerged as newly rising stars and drawn widespread interests of researchers due to their novel electrical and optical properties. Compared with common transition metal dichalcogenides, two-dimensional (2D) MPTs have larger optical bandgaps (from 1.3 to 3.5 eV), higher light absorption efficiency and richer bandgap structures due to the increased degree of freedom from the elements and atomic ratio, which highlight its great advantages in the field of optoelectronics. Among MPTs, In2/3PSe3 owns special structure, in which two-thirds of the octahedral holes are occupied by the indium ions and the other one-third are vacant. The unique structure endows In2/3PSe3 with intrinsic broken-symmetry, showing potential in non-linear optics. It was reported that bulk In2/3PSe3 is a direct-bandgap semiconductor (2.0 eV), in which the electron transition process from the conduction band to valence band is direct without phonon assisting, indicating great potential in application of optoelectronic devices. However, there is no research reported on the optoelectronic property of In2/3PSe3. According to the promising properties mentioned above, it is extremely urgent to characterize the optical and optoelectronic properties of 2D In2/3PSe3 nanosheets. In this work, high-quality In2/3PSe3 single crystals are synthesized by chemical vapor transport method and for the first time we achieve 2D In2/3PSe3 nanosheets on SiO2/Si substrate by mechanical exfoliation. X-ray diffractometer (XRD) and transmission electron microscope (TEM) are performed on In2/3PSe3 nanosheets, which demonstrate their high quality and single-crystalline nature. Considering that the non-centrosymmetric space group R 3, we further explored the SHG properties of In2/3PSe3 nanosheets. The intrinsic SHG response further verifies the broken-symmetry nature of In2/3PSe3. In addition, photoluminescence spectra of In2/3PSe3 nanosheets have revealed the exciton-like transition mechanism and longer PL lifetime than previously reported 2D materials, which may own to the high crystalline and low defects of as-synthesized crystals. To investigate the optoelectronic behavior of 2D In2/3PSe3 nanosheets, two-electrodes photodetectors based on In2/3PSe3 nanosheets are fabricated. Impressively, the In2/3PSe3 nanosheets-based photodetector exhibits an ultra-low dark current (25 fA), excellent detectivity (6.28 ´ 1011 Jones), high on/off ratio (4 ´ 104), and ultra-fast response rate (14 μs/24 μs) under 365 nm illumination, which are superior to other typical 2D ultraviolet photodetectors. The main photocurrent generation mechanism of the photodetector is photoconductive effect. The photogenerated free electrons and holes are separated rapidly to the opposite electrodes without trapping in defect states, leading to the ultra-fast response. These excellent optoelectronic behaviors of In2/3PSe3 nanosheet suggest its appealing prospect in future application of photodetection.