Jiuxiang Dai

In this work, a trace amount of MAI is added to the evaporation system in order to boost the performance of CsPbI₃ perovskite solar cells. When post-annealing conditions are not present, the processing window for obtaining γ-phase CsPbI₃ can be greatly extended by adding MAI. Simultaneously, MAI has the effect of modifying the perovskite crystal state to attain the orientation of the {001} crystal plane. Finally, the device's electrical performance and resistance to moisture attenuation have both been greatly enhanced.

Abstract

Cesium lead triiodide (CsPbI₃) perovskites have garnered significant attention owing to their suitable bandgap for tandem silicon substrates and excellent chemical stability. However, γ-CsPbI₃ prepared via low-temperature co-evaporation is limited by a narrow black phase processing window and random crystal orientation, hindering its optoelectronic performance and industrial applications. This study introduced trace amounts of methylammonium iodide (MAI) into the co-evaporation system, enhancing the crystallization process, promoting columnar grain growth, and stabilizing the γ-phase perovskite, resulting in films with improved structural integrity and reduced defect density. The optimal Pb/Cs ratio for achieving the best photoelectric performance shifted from 1:1 to 1.1:1 in the presence of MAI. Additionally, the incorporation of MAI allowed for more efficient longitudinal carrier transport, as evidenced by the enhanced photoluminescence (PL) intensity. The bandgap of CsPbI₃ remained approximately at 1.7 eV before the δ-phase transition, ensuring suitability for photovoltaic applications. Ultimately, a photovoltaic device with 12% efficiency is achieved in the p-i-n structure without additional post-annealing of the CsPbI₃ perovskite films, demonstrating the practical benefits of MAI incorporation.

In-plane growth mechanism of an electrohydrodynamic-driven structure is proposed to achieve uniform large-scale nanopattern replication in extended replication mode. Through the rapid in-plane growth with the controlled edge growth mode, the pattern replica area can be extended from the micro- to centimeter scale with high fidelity. The proposed route enables uniform large-scale patterning even in nonuniform contact mode.

Abstract

Nanopatterning driven by electrohydrodynamic (EHD) instability can aid in the resolution of the drawbacks inherent in conventional imprinting or other molding methods. This is because EHD force negates the requirement of physical contact and is easily tuned. However, its potential has not examined owing to the limited size of the pattern replica (several to tens of micrometers). Thus, this study proposes a new route for large-area patterning through high-speed evolution of EHD-driven pattern growth along the in-plane axis. Through the acceleration of the in-plane growth, while selectively controlling a specific edge growth, the pattern replica area can be extended from the micro- to centimeter scale with high fidelity. Moreover, even in the case of nonuniform contact mode, the proposed rapid in-plane growth mode facilitates uniform large-scale replication, which is not possible in conventional imprinting or other molding methods.

Author(s): Haitian Su, Ji-Yin Wang, Han Gao, Yi Luo, Shili Yan, Xingjun Wu, Guoan Li, Jie Shen, Li Lu, Dong Pan, Jianhua Zhao, Po Zhang, and H. Q. Xu

Under certain symmetry-breaking conditions, a superconducting system exhibits asymmetric critical currents, dubbed the “superconducting diode effect.” Recently, systems with the ideal superconducting diode efficiency or unidirectional superconductivity have received considerable interest. In this wo…

[Phys. Rev. Lett. 133, 087001] Published Wed Aug 21, 2024

Summarizing ion-selectivity regulation strategies (like regulating pH, oxidating channels, compounding charged polymers, introducing ionic groups, enhancing ion rectification, and constructing membrane pairs) and ion transport resistance regulation strategies (like reducing channel length, thinning membrane thickness, shortening transport paths, increasing channel height, elevating operating temperatures, and disrupting water molecule clusters) for the conversion of osmotic energy through angstrom-scale channels.

Abstract

Confronting the impending exhaustion of traditional energy, it is urgent to devise and deploy sustainable clean energy alternatives. Osmotic energy contained in the salinity gradient of the sea-river interface is an innovative, abundant, clean, and renewable osmotic energy that has garnered considerable attention in recent years. Inspired by the impressively intelligent ion channels in nature, the developed angstrom-scale 2D channels with simple fabrication process, outstanding design flexibility, and substantial charge density exhibit excellent energy conversion performance, opening up a new era for osmotic energy harvesting. However, this attractive research field remains fraught with numerous challenges, particularly due to the complexities associated with the regulation at angstrom scale. In this review, the latest advancements in the design of angstrom-scale 2D channels are primarily outlined for harvesting osmotic energy. Drawing upon the analytical framework of osmotic power generation mechanisms and the insights gleaned from the biomimetic intelligent devices, the design strategies are highlighted for high-performance angstrom channels in terms of structure, functionalization, and application, with a particular emphasis on ion selectivity and ion transport resistance. Finally, current challenges and future prospects are discussed to anticipate the emergence of more anomalous properties and disruptive technologies that can promote large-scale power generation.

A Janus PtSSe structure is designed and synthesized by controllable sulfur doping of 2D PtSe₂ ribbons during the chemical vapor deposition process. The PtSSe ribbons demonstrate significant symmetry breaking and enhanced electrical properties, showcasing a strong nonlinear optical response and synaptic plasticity.

Abstract

2D platinum diselenide (PtSe₂), a novel member of the transition metal dichalcogenides (TMDCs) family, possesses many excellent properties, including a layer-dependent bandgap, high carrier mobility, and broadband response, making it promise for applications in technologies like field-effect transistors and room-temperature photodetectors. Doping represents an effective method to modify the electrical properties of 2D TMDCs and to bestow upon them additional functions. However, to date, little research has been conducted on the successful doping of 2D PtSe₂ for modification. In this study, sulfur (S) powder is utilized during the chemical vapor deposition growth process of 2D PtSe₂ ribbons and successfully integrated into the PtSe₂ lattice through substitutional doping. The Au substrate significantly decreases the substitution energy of Se atoms in the lower layer of PtSe₂, resulting in the formation of the Janus PtSSe structure. S-doped PtSe₂ ribbons demonstrate significant symmetry breaking and enhanced electrical properties, showcasing a strong nonlinear optical response and certain synaptic plasticity, further simulating some neuromorphological processes. This study not only demonstrates a viable method for controllable doping and modification of 2D PtSe₂ but also establishes a platform for exploring the characteristics of Janus TMDCs.

Incorporation of carbon rings adjacent to CN frameworks of g-C₃N₄ ultrathin nanosheets forms heterojunction interfaces with an angle of 58° along both of their (100) lattice direction, which modulates the π-electron density over the nanosheets and enables superfast photocatalytic hydrogen production reaching a rate of 2231.8 µmol.g⁻¹.h⁻¹.

Abstract

The rational design and synthesis of novel semiconductor nano-/quantum materials have been ambitiously pursued in the field of photocatalysis as the technology is promising and critical for attaining future energy and environmental sustainability. Herein, the integrity of aromatic carbon into graphitic carbon nitride (CN) at the same molecular plane with a few 2D layers is achieved by using modulated precursors of CN, forming carbon regulated ultrathin CN (CUCN) with improved charge transfer kinetics and photocatalytic hydrogen production. The grafted graphite rings adjacent to carbon nitride frameworks induce a significant rearrangement and relocalization of the overall framework, and form conjugated sp² hybridized interfaces and internal electric fields that drive the separation and directional transfer of photogenerated electrons from CN sheets towards intralayer graphite regions, where the photocatalytic hydrogen evolution reaction occurs extensively, yielding largely increased HER rate of 2231.8 µmol g⁻¹ h⁻¹ by 8.2 times relative to CN, as well as a remarkable apparent quantum yield of 2.93% under monochromatic light at 420 nm. The high physicochemical stability and low synthesis cost of CUCN make it a potential benchmark photocatalyst that can be readily modified via element doping, heterojunction introduction, defect engineering, and so on, to further enhance its HER performance.

Single crystal diamonds heavily co-doped by nitrogen and boron can form numerous excitons confirmed by photoluminescence measurements. The degraded carrier mobility of diamond can transform superconductive state into metallic state under similar carrier concentration. The mechanism of superconductivity is correlated with the exciton Bose-Einstein condensations, which could realize higher temperature superconductive carbon materials, including graphene/diamond heterostructure.

Abstract

Owing to extremely large bandgap of 5.5 eV and high thermal conductivity, diamond is recognized as the most important semiconductor. The superconductivity of polycrystalline diamond has always been reported, but there are also many controversies over the existence of superconductivity in bulk single crystal diamond. Besides, it remains a question whether a metallic state exists for such a large bandgap semiconductor. Herein, a single crystal superconducting diamond with a Hall carrier concentration larger than 3 × 10²⁰ cm⁻³ is realized by co-doped of boron and nitrogen, with an extremely low resistivity of 2.07 × 10⁻³ Ω cm at room temperature and dominated acceptor–donor bounded exciton photoluminescence. Furthermore, it is shown that diamond can transform from superconducting to metallic state under similar carrier concentration with tuned carrier mobility degrading from 9.10 cm² V⁻¹ s⁻¹ or 5.30 cm² V⁻¹ s⁻¹ to 2.66 cm² V⁻¹ s⁻¹ or 1.34 cm² V⁻¹ s⁻¹. Through integrating graphene on a nitrogen and boron heavily co-doped diamond, a novel transportation behavior in the monolayer graphene similar with superconducting behavior is realized through combining Andreev reflection and exciton-mediated superconductivity, which may reveal more interesting superconducting behavior of diamond.

In this review, the recent advances of III–V semiconductor-based photodetectors are summarized from the aspects of synthetic approaches and detection applications. Their response to various electromagnetic wavelengths are comprehensively classified and compared. Based on the highlighted challenges and perspectives, this work can significantly enlighten the future development of III–V semiconductor-based photodetectors.

Abstract

The rapid advancement of main group III–V nanomaterials endows photodetectors (PDs) with enhanced performance. At present, various III–V nanomaterials are systematically investigated, whereof III–V semiconductors have attracted a successively increased attention that calls for a comprehensive summary which also can define the state-of-art for their further development. Herein, this work systematically introduces and discusses key aspects of the field. First, the advanced strategies for the preparation of III–V semiconductor materials and the device structures of the subsequent PDs based on these materials, pristine and doped, are addressed. The focus is then turned to their performance under the irradiation of various wavelengths, separately summarizing and comparing the photodetection properties under infrared, UV and visible light. Finally, challenges and future perspectives of III–V semiconductor-based PDs are highlighted. This review  enlightens the development of III–V semiconductor-based PDs, and their extended applications for optoelectronic devices in general.

Material genes dominate the electromagnetic properties of 2D materials. The genes encoding dielectric materials include polarization and conduction genes. Tailoring polarization and conduction genes is an effective strategy to construct effective electromagnetic materials by introducing new materials and microstructures, resembling “genetic engineering”. The exploration of dielectric gene tailoring is promising for developing multispectral and multifunctional electromagnetic applications.

Abstract

2D materials and their composites with electromagnetic properties are becoming increasingly popular. Obtaining insight into the nature of electromagnetic (EM) response manipulation is imperative to guide scientific research and technological exploitation at such a critical time. From this perspective, the dielectric genes of 2D material hybrids have been highlighted based on the recent literature. This endows an unlimited possibility of manipulating the EM response, even at elevated temperatures. The definitions and criteria of dielectric genes toward 2D material hybrids and composites are systematically clarified and summarized. The dielectric gene categories are successfully discriminated, including the conduction networks, intrinsic defects, impurity defects, and interfaces in the composite, and their temperature evolution is revealed in detail. More importantly, tuning strategies for microwave absorption, electromagnetic shielding effectiveness, and expanded electromagnetic functions are thoroughly discussed. Finally, significant predictions are provided for multispectral electromagnetic functions, and future applications of multifunctional exploration are anticipated. Dielectric genes will open an unexpected horizon for advanced functional materials in the coming 5G/6G age, providing a significant boost to promoting environmental electromagnetic protection, electromagnetic devices, and next-generation smart devices.

Nature Reviews Materials, Published online: 23 August 2024; doi:10.1038/s41578-024-00718-6

An article in Science Robotics presents a high-energy-density, picolitre-sized battery.

Light: Science & Applications, Published online: 23 August 2024; doi:10.1038/s41377-024-01551-w

Breaking anisotropy limitations in thin-film lithium niobate arrayed waveguide gratings

This study explores the controlled oxidation of layered GaS to achieve GaS_xO_y/GaS heterostructures and their application in resistive random-access memories (ReRAM). The approach results in ultra-thin, amorphous oxide with a sharp interface with the underlying semiconductor. The GaS_xO_y/GaS ReRAM devices show sub-nJ energy consumption, highlighting their potential for neuromorphic computing applications.

Abstract

Oxidation of 2D layered materials has proven advantageous in creating oxide/2D material heterostructures, opening the door for a new paradigm of low-power electronic devices. Gallium (II) sulfide (β-GaS), a hexagonal phase group III monochalcogenide, is a wide bandgap semiconductor with a bandgap exceeding 3 eV in single and few-layer form. Its oxide, gallium oxide (Ga₂O₃), combines a large bandgap (4.4–5.3 eV) with a high dielectric constant (≈10). Despite the technological potential of both materials, controlled oxidation of atomically-thin β-GaS remains under-explored. This study focuses on the controlled oxidation of β-GaS using oxygen plasma treatment, addressing a significant gap in existing research. The results demonstrate the ability to form ultrathin native oxide (GaS_xO_y), 4 nm in thickness, upon exposure to 10 W of O₂, resulting in a GaS_xO_y/GaS heterostructure where the GaS layer beneath remains intact. By integrating such structures between metal electrodes and applying electric stresses as voltage ramps or pulses, their use for resistive random-access memory (ReRAM) is investigated. The ultrathin nature of the produced oxide enables low operation power with energy use as low as 0.22 nJ per operation while maintaining endurance and retention of 350 cycles and 10⁴ s, respectively. These results show the significant potential of the oxidation-based GaS_xO_y/GaS heterostructure for electronic applications and, in particular, low-power memory devices.

Nature Electronics, Published online: 26 August 2024; doi:10.1038/s41928-024-01233-w

Metal gate electrodes with a high cohesive energy—platinum and tungsten—can be used to mitigate leakage currents and premature dielectric breakdown across chemical vapour deposition-grown multilayer hexagonal boron nitride, allowing the material to be used as a gate dielectric in two-dimensional-materials-based transistors.

Nature, Published online: 21 August 2024; doi:10.1038/s41586-024-07826-x

An on-chip platform with in situ adjustable interfacial properties, using a microelectromechanical system, provides multi-degree-of-freedom control of two-dimensional materials, including twisting and pressurizing.

Nature, Published online: 21 August 2024; doi:10.1038/d41586-024-02634-9

Single crystals of atomically thin sapphire have been prepared at room temperature — something that many scientists thought was impossible. These materials could enable the development of the next generation of transistors for use in miniaturized chips.

Nature Chemistry, Published online: 27 August 2024; doi:10.1038/s41557-024-01617-7

Understanding the structural rearrangements of infinite-layer transition metal oxides at the atomic level remains challenging. Now in situ electron microscopy has been used to monitor the formation of infinite-layer SrFeO2 through an oxygen deintercalation process; lattice flexibility of the FeOx polyhedral layers facilitates the phase transformation.

Nature Communications, Published online: 23 August 2024; doi:10.1038/s41467-024-51567-4

Microbot collectives can cooperate to accomplish complex tasks that are difficult for a single individual. Here, the authors report magnetic and light-driven ant microbot collectives that are capable of reconfiguring multiple assembled architectures.