Jing Zhang

Nature Photonics, Published online: 01 August 2022; doi:10.1038/s41566-022-01042-7

Lanthanide nanotransducers are developed to detect broadband incoherent mid-infrared radiation in the 4–11 μm spectral window by ratiometric luminescence measurements.

Nature Physics, Published online: 01 August 2022; doi:10.1038/s41567-022-01643-7

Interactive protocols can verify that a quantum computer exhibits a computational speedup using only classical analysis of its output. Exploiting a connection to Bell’s theorem gives a simpler protocol that is much less demanding for experiments.

Nature Electronics, Published online: 01 August 2022; doi:10.1038/s41928-022-00801-2

Two laser beams with different energies and configurations can be used to reversibly dope graphene via chlorination and chlorine removal, allowing rewritable graphene photodetectors to be fabricated.

Nature Communications, Published online: 26 July 2022; doi:10.1038/s41467-022-31763-w

Integrating ferroelectric perovskite oxides on Si is highly desired for electronic applications but challenging. Here, the authors show emergent in-plane ferroelectricity and promising nonvolatile memories based on resistive domain wall in BaTiO3/Si.

Nature, Published online: 27 July 2022; doi:10.1038/d41586-022-01987-3

A cryptographic scheme offers a secure way of exchanging data using a phenomenon called quantum entanglement. The approach relies on special quantum correlations between particles that help to prevent tampering.

Nature, Published online: 27 July 2022; doi:10.1038/s41586-022-04855-2

An alternating stack of a candidate spin liquid and a superconductor shows a spontaneous vortex phase in the superconducting state without magnetism in the normal state. This indicates the presence of unconventional magnetic ordering independent of the superconductor.

The study of magnetic order in few- and monolayer van der Waals materials poses a challenge to the most commonly employed magnetic characterization techniques as they normally lack magnetic sensitivity and/or lateral resolution enabling their thickness-dependent probing. Here we demonstrate the usefulness of x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements, carried out at the Cr ##IMG## [https://cfn-live-content-bucket-iop-org.s3.amazonaws.com/journals/2053-1583/9/4/045007/revision2/tdmac7b96ieqn1.gif?AWSAccessKeyId=AKIAYDKQL6LTV7YY2HIK&Expires=1660535997&Signature=iKBYHAmJzYJcNg%2FuD0lOolIdbgU%3D] {$L_{2,3}$} and Te M 5 edges, for the study of the ferromagnetic semiconductor CrSiTe 3 (CST) in the form of single- and few-layer flakes. By scanning the sample under the incident x-ray beam, a map of the exfoliated system was obtained, which reproduced the optical micrographs showing the detailed distribution and thicknesses of the flakes. In this way, XAS/XMCD was performed at selected sample areas, revealing the thickness-resolved spectroscopic and magnetic properties of the flakes, such as the spin and orbital magnetic moments. The spin moment, in line with the saturation field, is decreasing with film thickness, revealing a single-domain and out-of-plane magnetization for the thinnest films. For CST, the electronic properties are governed by the strong covalent bond between the Cr 3 d ( e g ) and Te 5 p states, giving rise to a superexchange scenario. We observed a gradually increasing ratio of orbital to spin moment for thinner flakes, which could be due to a further increase of the covalent mixing. Hysteresis loops were recorded at the Cr L 3 edge, showing an open loop for 10 down to ∼3 layers, while the bulk shows a wasp-waist shaped loop. With the transition temperature from the soft to the hard ferromagnetic state decreasing with thickness, the monolayer shows a narrowed, closed loop at 10 K, suggesting its transition temperature ##IMG## [https://cfn-live-content-bucket-iop-org.s3.amazonaws.com/journals/2053-1583/9/4/045007/revision2/tdmac7b96ieqn2.gif?AWSAccessKeyId=AKIAYDKQL6LTV7YY2HIK&Expires=1660535997&Signature=8%2B7eD3Lfc1J56MlJHD5qJyQa5Q0%3D] {$\gt$} 10 K. Our study demonstrates the unique capabilities of XAS/XMCD for the study of few-layer van der Waals magnets, highlighting the interplay between electron correlation and ferromagnetism in CST.

Aqueous zinc-ion batteries (ZIBs) are considered as a promising energy storage system for large-scale energy storage in terms of their high safety and low cost. In recent years, two-dimensional (2D) materials have been widely applied in designing the electrodes of aqueous ZIBs since they generally possess the characteristics of large surface areas, plentiful ion transport channels and abundant active sites. Thus, they can not only act as the active materials and conductive additives in cathodes, but also be employed as the artificial interface layers or conductive substrates of Zn anodes. In this review, the issues of aqueous ZIBs and the unique properties of 2D materials are discussed briefly. Then we highlight the recent advances of the applications of various 2D materials, mainly including transition metal oxides, transition metal dichalcogenide, graphene and MXenes, in the design of the cathodes and anodes of aqueous ZIBs. Finally, we present the challenges and perspectives of 2D materials in aqueous ZIBs.

Nature Electronics, Published online: 26 July 2022; doi:10.1038/s41928-022-00815-w

Multiple ReRAM on a chip increases compute density

Nature Electronics, Published online: 26 July 2022; doi:10.1038/s41928-022-00817-8

Reducing the heat in CMOS multiplexers

Nature Electronics, Published online: 26 July 2022; doi:10.1038/s41928-022-00814-x

Extreme-ultraviolet lithography packs more transistors on chip

Nature Electronics, Published online: 26 July 2022; doi:10.1038/s41928-022-00818-7

Wafer-scale transfer of tungsten disulfide

The modulation of the thermometric properties of a mixed Eu–Tb metal–organic framework (MOF) through the post-synthetic modification method is reported. The exchange of the terminal DMF molecules of the pristine Eu–Tb MOF by terminal N-donor or chelating N/O-donor aromatic ligands leads to an offset of 50 degrees of the operating temperature while maintaining a very good thermal sensitivity.

Abstract

An initial investigation on the employment of targeted structural alterations, achieved through the post-synthesis modification method, for modulation of the thermometric properties of metal–organic frameworks (MOFs) is reported. The MOF Eu_0.05Tb_0.95-NBDC (NBDC = 2-amino-1,4-benzenedicarboxylate) is chosen as pristine material, and its terminal N,N-dimethylformamide (DMF) molecules are exchanged by various terminal and chelating ligands through a single-crystal-to-single-crystal coordinating solvent exchange reaction. Temperature-dependence luminescence studies reveal that all samples are highly sensitive in the medium range with a maximum relative sensitivity of 2.6% K⁻¹ at 190 K for Eu_0.05Tb_0.95-NBDC. In addition, a shift of 50 K of the operating temperature range is evidenced for the exchanged analogs. This is attributed to the occurrence of different deactivation pathways in the exchanged analogs due to the presence of N-donor terminal or N/O-donor chelating aromatic ancillary ligands in the place of DMF terminal ligands in the pristine material. Overall, this work provides insights into the role of terminal and chelating ligands on the thermometric properties of mixed Eu–Tb MOFs and proposes a promising strategy to control and modulate their thermometric performances.

2D perovskites entail the virtue of both inorganic and organic room-temperature phosphorescence (RTP) materials, and are thereby capable of strong and persistent phosphorescence for making future-generation RTP materials. A multistep high-throughput screening strategy integrating the Dexter-type energy transfer mechanism, excited state properties of inorganic and organic components, and molecular morphing operators are developed to effectively discover novel 2D perovskites with desired phosphorescence emission.

Abstract

Functional materials with room-temperature phosphorescence (RTP) are highly desired for optoelectronic and bio-imaging applications. Currently, most inorganic RTP materials require exceedingly expensive rare metals. Although organic materials have the advantages of low cost and facile fabrication, their quantum yields are quite poor due to low efficiency in the intersystem crossing process. 2D hybrid organic-inorganic perovskites (2D HOIPs), however, entail the virtue of both inorganic and organic RTP materials, thereby capable of strong and persistent phosphorescence for making future-generation RTP materials. Herein, an effective screening approach is presented to search for 2D HOIPs as efficient RTP materials. The guidelines for this high-throughput screening include the Dexter-type energy transfer mechanism, the computed excited-state properties, and the molecular morphing operators. Moreover, the structural stability of the 2D HOIPs is assessed by using a newly proposed tolerance factor. Overall, 539 candidates are identified as promising 2D HOIP materials for RTP. In particular, four 2D HOIPs, namely, (thNfuEA)₂PbBr₄, (selBthEA)₂PbBr₄, (selBfuEA)₂PbBr₄, and (BselBthEA)₂PbBr₄, are predicted to possess robust room-temperature stability, suitable energy level and proper frontier-orbital alignment, thus hold high potential for functional optoelectronic applications.

Low-dimensional light-emitting materials have presented peculiar optical and optoelectronic properties, unlike their bulk form. The light–matter interaction of these emitters can be engineered by integrating with various planar optical cavities, which is a planar nano- and microstructure that tightly confines light. These integrations provide opportunities for realizing nanophotonic devices based on the new physics allowed by low-dimensional emitters.

Abstract

Low-dimensional light-emitting materials have been actively investigated due to their unprecedented optical and optoelectronic properties that are not observed in their bulk forms. However, the emission from low-dimensional light-emitting materials is generally weak and difficult to use in nanophotonic devices without being amplified and engineered by optical cavities. Along with studies on various planar optical cavities over the last decade, the physics of cavity–emitter interactions as well as various integration methods are investigated deeply. These integrations not only enhance the light–matter interaction of the emitters, but also provide opportunities for realizing nanophotonic devices based on the new physics allowed by low-dimensional emitters. In this review, the fundamentals, strengths and weaknesses of various planar optical resonators are first provided. Then, commonly used low-dimensional light-emitting materials such as 0D emitters (quantum dots and upconversion nanoparticles) and 2D emitters (transition-metal dichalcogenide and hexagonal boron nitride) are discussed. The integration of these emitters and cavities and the expect interplay between them are explained in the following chapters. Finally, a comprehensive discussion and outlook of nanoscale cavity-emitter integrated systems is provided.

A single-molecule memristor with long-lasting retained memory states, high write–erase endurance, and adjustable on/off ratio is realized by a novel mechanism—dynamical structure reconfiguration in the Fries rearrangement. Precise manipulation of the potential energy surface of the reaction by external electric fields can retain and switch the corresponding desired species along the reaction coordinate to achieve a memory effect.

Abstract

A robust single-molecule memristor is prepared by covalently integrating one phenol molecule with multiple binding sites into nanogapped graphene electrodes. Multilevel resistance switching is realized by the electric-field-manipulated reconfiguration of the acyl moiety on the phenol center, that is, the Fries rearrangement. In situ measurements of the reaction trajectories with an initial single substrate and an intermediate break through the limitation of macroscopic experiments, therefore unveiling both intramolecular and intermolecular mechanistic pathways (a long-term controversy) as well as comprehensive dynamic information. Based on this advance, high-performance single-molecule memristors in both the solution and solid states are achieved successively, providing a new understanding of memristive systems and neural network computing.

Organic Semiconductors

3D printing of electronics has received growing attention due to their potential applications in emerging fields such as nanoelectronics and nanophotonics. In article number 2200512, Mohammad Reza Abidian and co-workers introduce a homogenous and transparent photosensitive resin doped with an organic semiconductor material compatible with the multiphoton lithography process to fabricate a variety of 3D flexible microelectronic devices, bioelectronics, and biosensors. The results demonstrate the great potential of these novel devices for various applications in the emerging fields of flexible bioelectronics/biosensors, nanoelectronics, organ-on-chips, and immune cell therapies.

Multi-valued logic (MVL) is an effective means of increasing the bit density and reducing the power consumptions of modern chips. A comprehensive review and classification of the state-of-the-art compact MVL unit devices is presented. Special emphasis is placed on a comparative discussion of advantages and limitations of each class of MVL devices.

Abstract

Ever since the invention of solid-state transistors, binary devices have dominated the electronics industry. Although the binary technology links the natural property of devices to be in the ON or OFF state with two logic levels, it provides the least possible information content per interconnect. Multi-valued logic (MVL) has long been considered as a means of improving the computation efficiency and reducing the power consumption of modern chips. In view of the power density limits of the conventional complementary metal–oxide–semiconductor technology, MVL technologies have recently gained even more attention, and various MVL unit devices based on conventional and emerging materials have been proposed. Herein, the recent achievements toward the development of compact MVL unit devices are reviewed. First, basic principles of MVL technologies are introduced by describing methods of obtaining multiple logic states and discussing radix-related aspects of MVL computation. Next, MVL unit devices are classified and overviewed with emphasis on principles of operation, technologies, and applications. Finally, a comparative discussion of strengths and weaknesses is provided for each class of MVL devices, and the review concludes with the outlook for the MVL field.

A new platform is developed for assembling freestanding oxide thin films with different materials and orientations into artificial stacks of heterointerfaces. The heterointerfaces can be tailored by controlling the stacking sequences, as well as the twist angle between the constituent layers with atomically sharp interfaces, leading to distinct moiré patterns.

Abstract

The integration of dissimilar materials in heterostructures has long been a cornerstone of modern materials science—seminal examples are 2D materials and van der Waals heterostructures. Recently, new methods have been developed that enable the realization of ultrathin freestanding oxide films approaching the 2D limit. Oxides offer new degrees of freedom, due to the strong electronic interactions, especially the 3d orbital electrons, which give rise to rich exotic phases. Inspired by this progress, a new platform for assembling freestanding oxide thin films with different materials and orientations into artificial stacks with heterointerfaces is developed. It is shown that the oxide stacks can be tailored by controlling the stacking sequences, as well as the twist angle between the constituent layers with atomically sharp interfaces, leading to distinct moiré patterns in the transmission electron microscopy images of the full stacks. Stacking and twisting is recognized as a key degree of structural freedom in 2D materials but, until now, has never been realized for oxide materials. This approach opens unexplored avenues for fabricating artificial 3D oxide stacking heterostructures with freestanding membranes across a broad range of complex oxide crystal structures with functionalities not available in conventional 2D materials.

The enriched-bromine surface state is controlled by employing PbBr₂ stock solution for anion-exchange based on Cd-doping perovskite quantum dots (QDs), which shows good passivation to the vacancy defects, resulting in boosted optical properties and stability. The stable sky-blue spectrum quantum-dot light-emitting diodes (QLEDs) based on the controlled QDs are conducted with a record EQE of 14.6% and current efficiency (CE) of 19.9 Cd A⁻¹.

Abstract

Halogen vacancies are of great concern in blue-emitting perovskite quantum-dot light-emitting diodes because they affect their efficiency and spectral shift. Here, an enriched-bromine surface state is realized using a facile strategy that employs a PbBr₂ stock solution for anion exchange based on Cd-doped perovskite quantum dots. It is found that the doped Cd ions are expected to reduce the formation energy of halogen vacancies filled by the external bromine ions, and the excess free bromine ions in solution are enriched in the surface by anchoring with halogen vacancies as sites, accompanied with the shedding of surface long-chain ligands during the anion exchange process, resulting in a Br-rich and “neat” surface. Moreover, the surface state exhibits good passivation of the surface defects of the controlled perovskite QDs and simultaneously increases the exciton binding energy, leading to excellent optical properties and stability. Finally, the sky-blue emitting perovskite quantum-dot light-emitting diodes (QLEDs) (490 nm) are conducted with a record external quantum efficiency of 14.6% and current efficiency of 19.9 cd A⁻¹. Meanwhile, the electroluminescence spectra exhibit great stability with negligible shifts under a constant operating voltage from 3 to 7 V. This strategy paves the way for improving the efficiency and stability of perovskite QLEDs.

Monolayers of Janus SeMoS with asymmetric top (Se) and bottom (S) chalcogen atomic planes with respect to the central transition metal (Mo) atoms are synthesized using a one-pot chemical vapor deposition process and its high optical quality is demonstrated by low-temperature magneto optical spectroscopy.

Abstract

One-pot chemical vapor deposition (CVD) growth of large-area Janus SeMoS monolayers is reported, with the asymmetric top (Se) and bottom (S) chalcogen atomic planes with respect to the central transition metal (Mo) atoms. The formation of these 2D semiconductor monolayers takes place upon the thermodynamic-equilibrium-driven exchange of the bottom Se atoms of the initially grown MoSe₂ single crystals on gold foils with S atoms. The growth process is characterized by complementary experimental techniques including Raman and X-ray photoelectron spectroscopy, transmission electron microscopy, and the growth mechanisms are rationalized by first principle calculations. The remarkably high optical quality of the synthesized Janus monolayers is demonstrated by optical and magneto-optical measurements which reveal the strong exciton–phonon coupling and enable an exciton g-factor of −3.3.

Nature Communications, Published online: 22 July 2022; doi:10.1038/s41467-022-31851-x

Twisted van der Waals structures represent a versatile platform to investigate topological and correlated electronic states. Here, the authors report the visualization of an electron crystal phase in twisted monolayer-bilayer graphene via scanning tunnelling microscopy, studying the coupling between strong electron correlation and nontrivial band topology.

Boron arsenide is a semiconductor with high thermal conductivity and electron-hole mobility.