#TeddersRecommends

2D organic materials with in-plane van der Waals forces among molecules have unique characteristics that ensure a brilliant future for multifunctional applications. Soluble organic semiconductors can be used to achieve low-cost and high-throughput manufacturing of electronic devices. However, achieving solution-processed 2D single-crystalline semiconductors with uniform morphology remains a substantial challenge. Here, the fabrication of 2D molecular single-crystal semiconductors with precise layer definition by using a floating-coffee-ring-driven assembly is presented. In particular, bilayer molecular films exhibit single-crystalline features with atomic smoothness and high film uniformity over a large area; field-effect transistors yield average and maximum carrier mobilities of 4.8 and 13.0 cm² V⁻¹ s⁻¹, respectively. This work demonstrates the strong potential of 2D molecular crystals for low-cost, large-area, and high-performance electronics.

The floating-coffee-ring-driven assembly of 2D single-crystalline molecular semiconductors with precise layer definition is presented. Typical single-crystalline features, atomic smoothness, and high morphologic uniformity over a large area are achieved. Field-effect transistors devices yield a maximum carrier mobility of 13.0 cm² V⁻¹ s⁻¹ and thus show promise for low-cost, large-area, and high-performance electronics.

Single- and few-layer MoS₂ nanoflowers are first discovered to have a piezo-catalyst effect, exhibiting an ultra-high degradation activity in the dark by introducing external mechanical strains. The degradation ratio of the Rhodamine-B dye solution reaches 93% within 60 s under ultrasonic-wave assistance in the dark.

The room-temperature synthesis of a new two-dimensional (2D) zirconium-containing carbide, Zr₃C₂T_z MXene is presented. In contrast to traditional preparation of MXene, the layered ternary Zr₃Al₃C₅ material instead of MAX phases is used as source under hydrofluoric acid treatment. The structural, mechanical, and electronic properties of the synthesized 2D carbide are investigated, combined with first-principles density functional calculations. A comparative study on the structrual stability of our obtained 2D Zr₃C₂T_z and Ti₃C₂T_z MXenes at elevated temperatures is performed. The obtained 2D Zr₃C₂T_z exhibits relatively better ability to maintain 2D nature and strucural integrity compared to Ti-based Mxene. The difference in structural stability under high temperature condition is explained by a theoretical investigation on binding energy.

Zr₃C₂T_z nanosheets: A 2D zirconium-containing carbide, Zr₃C₂T_z MXene, is obtained by selective etching of Al₃C₃ units from layered ternary Zr₃Al₃C₅ beyond MAX phases (see picture) at room temperature. The structural, mechanical, and electronic properties of the 2D carbide were investigated combined with density functional calculations. The 2D Zr₃C₂T_z exhibits excellent thermal stability, which exists even at 1200 °C in vacuum.

Rational nanoscale surface engineering of electroactive nanoarchitecture is highly desirable, since it can both secure high surface-controlled energy storage and sustain the structural integrity for long-time and high-rate cycling. Herein, ultrasmall MoS₂ quantum dots (QDs) are exploited as surface sensitizers to boost the electrochemical properties of Li₄Ti₅O₁₂ (LTO). The LTO/MoS₂ composite is prepared by anchoring 2D LTO nanosheets with ultrasmall MoS₂ QDs using a simple and effective assembly technique. Impressively, such 0D/2D heterostructure composites possess enhanced surface-controlled Li/Na storage behavior. This unprecedented Li/Na storage process provides a LTO/MoS₂ composite with outstanding Li/Na storage properties, such as high capacity and high-rate capability as well as long-term cycling stability. As anodes in Li-ion batteries, the materials have a stable specific capacity of 170 mAhg⁻¹ after 20 cycles and are able to retain 94.1% of this capacity after 1000 cycles, i.e., 160 mAhg⁻¹, at a high rate of 10 C. Due to these impressice performance, the presented 0D/2D heterostructure has great potential in high-performance LIBs and sodium-ion batteries.

A smart hybrid of ultrasmall MoS₂-quantum-dot-interspersed LTO nanosheets is prepared. The 0D/2D heterostructure of the LTO/MoS₂ composite conduces to enhanced surface-controlled Li/Na storage behavior, resulting in high capacity, extraordinary rate capability, and remarkable cycling stability.

Two-dimensional inorganic materials are emerging as a premiere class of materials for fabricating modern electronic devices. The interest in 2D layered transition metal dichalcogenides is especially high. Particularly, 2D MoS₂ is being heavily researched due to its novel functionalities and its suitability for a wide range of electronic and optoelectronic applications. In this article, the progress in mono/few layer(s) MoS₂ research is reviewed by focusing primarily on the layer dependent evolution of crystal, phonon, and electronic structure. The review includes extensive detail into the methodologies adapted for single or few layer(s) MoS₂ growth. Further, the review covers the versatility of 2D MoS₂ for a broad range of device applications. Recent advancements in the field of van der Waals heterostructures are also highlighted at the end of the review.

The recent emergence of atomically thin 2D materials beyond graphene opened up the platform for new device designs. This review covers recent progress in atomically thin MoS₂ research, including a description of layer-dependent evolution of the crystal structure, phonon properties and electronic structure, and various methodologies adapted for single- or few-layer MoS₂ growth. It also covers the versatility of 2D MoS₂ for a broad range of electronic and optoelectronic device applications.

Planar perovskite solar cells (PSCs) fabricated by intramolecular exchange with PbI₂(DMSO) and PbI₂(NMP) complexes and the high performance of these cells are described. Their films are easily deposited with a one-step spray-coating and were effectively converted into high-quality FAPbI₃-based perovskite layers. PbI₂(NMP)-derived PSCs yielded a power conversion efficiency as high as 19.5%, higher than that of PbI₂(DMSO)-derived PSCs.

Hybrid perovskites have generated a great deal of interest because of their potential in photovoltaic applications. However, the toxicity of lead means that there is interest in finding a nontoxic substitute. Bulk single crystals of both cubic CH₃NH₃SnI₃ and CH(NH₂)₂SnI₃ were obtained by using the top-seeded solution growth method under an ambient atmosphere. Structural refinement, band gap, thermal properties, and XPS measurements of CH₃NH₃SnI₃ and CH(NH₂)₂SnI₃ single crystals are also reported in detail. These results should pave the way for further applications of CH₃NH₃SnI₃ and CH(NH₂)₂SnI₃.

Unleaded: Bulk single crystals of lead-free perovskites CH₃NH₃SnI₃ and CH(NH₂)₂SnI₃ can be obtained by top-seeded solution growth under an ambient atmosphere. CH₃NH₃SnI₃ acts as a p-type semiconductor, while CH(NH₂)₂SnI₃ behaves as an n-type semiconductor. CH(NH₂)₂SnI₃ was found to be more stable than CH₃NH₃SnI₃ after storage under an ambient atmosphere for one month.

Two-dimensional (2D) transition-metal dichalcogenide (TMD) nanosheets have emerged as a fascinating new class of materials for catalysis. These nanosheets are active for several important catalysis reactions including hydrogen evolution from water. The rich chemistry of TMDs combined with numerous strategies that allow tuning of their electronic properties make these materials very attractive for understanding the fundamental principles of electro- and photocatalysis, as well as for developing highly efficient, renewable, and affordable catalysts for large-scale production of hydrogen. Recent developments are highlighted and important challenges in using TMDs as catalysts are also discussed.

Transition metal dichalcogenide (TMD) nanosheets are promising catalysts for evolution of hydrogen. TMDs possess a wide range of electronic and catalytic properties so that important fundamental parameters related to catalysis can be investigated. Recent progress on the study of 2D TMD nanosheets for enhancing their electro- and photocatalytic activity is discussed.

2D semiconductors have emerged as a crucial material for use in next-generation optotelectronics. Similar to microelectronic devices, 2D vertical heterostructures will most likely be the elemental components for future nanoscale electronics and optotelectronics. To date, the components of mostly reported 2D van der Waals heterostructures are restricted to layer crystals. In this work, it is demonstrated that nonlayered semiconductors of CdS can be epitaxially grown on to 2D layered MoS₂ substrate to form a new quasi vertical heterostructure with clean interface by chemical vapor deposition. Photodetectors based on this CdS/MoS₂ heterostructure show broader wavelength response and ≈50-fold improvement in photoresponsivity, compared to the devices fabricated from MoS₂ monolayer only. This research opens up a way to fabricate a variety of functional quasi heterostructures from nonlayered semiconductors.

A new van der Waals heterostructure consisting of semiconducting CdS nanosheets and MoS₂ is epitaxially grown onto a 2D layered crystal via Chemical Vapor Deposition. Photodetectros based on this novel heterostructure show a significant enhancement in photocurrent and photoresponsivity compared to MoS₂ photodetectors.

MoS₂/montmorillonite (MoS₂/MMT) composite nanosheets have been successfully synthesized by a facile hydrothermal method, and the catalytic activities of composites are evaluated by reduction reaction of methyl orange in aqueous phase. A preparation strategy demonstrates that MoS₂ can be in situ formed on the surface of MMT from Na₂MoO₄· and H₂NCSNH₂. The microstructures and morphologies characterization indicates that few-layered MoS₂ nanosheets are uniformly grown on the surface of montmorillonite, and the hydrogen bonds are formed at the interfaces. The catalytic activity of MoS₂/MMT is enhanced by support of montmorillonite, which can be attribu­ted to the large surface area, more reactive sites, dispersibility of MoS₂/MMT, and the synergistic adsorption property of montmorillonite. Based on density functional theory calculations, the preferred adsorption configurations of MoS₂ cluster on MMT are studied. The supporting effect of MMT on MoS₂ nanoparticles will lead to the anchoring of these reactive MoS₂ nanoparticles on clay surface and enhance the absorption ability of MoS₂ to the organics and meanwhile improving the catalytic properties of the MoS₂/MMT composite. The MoS₂/MMT composite nanosheets show prospective application to treat effectively wastewater of dyes.

MoS₂/montmorillonite (MoS₂/MMT) composite nanosheets have been successfully synthesized with MoS₂ in situ formed on the surface of MMT via hydrogen bonds. The enhanced catalytic activi­ty of MoS₂/MMT can be attributed to the large surface area, more reactive sites, dispersibility, and the synergistic adsorption property of MMT. Further DFT calculations indicate the preferred adsorption configurations of MoS₂ cluster on MMT.