Recent progress of flexible electronics by 2D transition metal dichalcogenides

Flexible electronics is the research field with interdisciplinary crossing and integration.It shows the promising advantages of novel device configurations,low-...     

Substitutional doping in 2D transition metal dichalcogenides

Nano Research - Two-dimensional (2D) van der Waals transition metal dichalcogenides (TMDs) are a new class of electronic materials offering tremendous opportunities for advanced technologies and...     

p-/n-Type modulation of 2D transition metal dichalcogenides for electronic and optoelectronic devices

Two-dimensional layered transition metal dichalcogenides(TMDCs)have demonstrated a huge potential in the broad fields of optoelectronic devices,logic electronics,electronic integration,as well as neural networks.To take full advantage of TMDC characteristics and efficiently design the device structures,one of the most key processes is to control their p-/n-type modulation.In this review,we summarize the p-/n-type modulation of TMDCs based on diverse strategies consisting of intrinsic defect tailoring,substitutional doping,surface charge transfer,chemical intercalation,electrostatic modulation,and dielectric interface engineering.The modulation mechanisms and comparisons of these strategies are analyzed together with a discussion of their corresponding device applications in electronics and optoelectronics.Finally,challenges and outlooks for p-/n-type modulation of TMDCs are presented to provide references for future studies.     

Synthesis of well-dispersed TiO2 nanorods and their application in hybrid ultraviolet photodetectors

Highly crystalline and well-dispersed TiO₂ nanorods have been prepared by well-controlled solvothermal reactions and applied to fabricate inorganic/polymer hybrid ultraviolet photodetectors. The incorporation of TiO₂ nanorods could substantially improve device performance because of the widespread interface area between two components and yield a very promising device performance of high ultraviolet photo-to-dark current ratio of nearly three orders of magnitude with short response time of less than 200 ms. The proposed method provides a new route for fabricating low-cost, environmentally friendly hybrid bulk heterojunction ultraviolet photodetectors.     

Valleytronics in transition metal dichalcogenides materials

Nano Research - Valley degree of freedom in the first Brillouin zone of Bloch electrons offers an innovative approach to information storage and quantum computation. Broken inversion symmetry...     

Recent Advances in Synthesis and Applications of 2D Junctions

Recent progress in the methods of integration of 2D materials is reviewed. Integrated 2D circuits are one of the most promising candidates for advanced electronics and flexible devices. Specifically, methods such as mechanical transfer, chemical vapor deposition growth, high temperature conversion, phase engineering, surface doping, electrostatic doping, and so on to fabricate 2D heterostructures are discussed in detail. Applications of these integrated 2D heterostructures in p–n junctions, ohmic contact, high‐performance transistors, and phototransistors are also highlighted. Finally, challenges and opportunities of methods to integrate 2D materials are proposed.     

Harmonic generation in transition metal dichalcogenides and their heterostructures

Few layered transition metal dichalcogenides (TMD), with an absence of crystal inversion symmetry and outstanding optical characteristics, are frequently applied in studies of nonlinear optics (NLO) for harmonic generation. Related materials are regarded as potential candidates for many optoelectronics applications. In order to enhance and manipulate the intrinsically weak NLO responses, TMD’s have been fabricated into heterostructures in recent years. The basic physics of harmonic generation and of TMD optical responses, as well as the interactions in TMD hybrid structures are introduced briefly, and the current state-of-the-art in the performance of TMDs in harmonic generation are reviewed. A particular focus is made on heterostructure studies to enhance and manipulate the response, which represent the core issues for devices and applications.     

Recent progress in transparent oxide semiconductors: Materials and device application

This paper reviews our recent research progress on new transparent conductive oxide (TCO) materials and electronic and optoelectronic devices based on these materials. First, described are the materials including p-type materials, deep-UV transparent TCO(β-Ga₂O₃), epitaxially grown ITO with atomically flat surface, transparent electrochromic oxide (NbO₂F), amorphous TCOs, and nanoporous semiconductor 12CaO · 7Al₂O₃. Second, presented are TCO-based electronic/optoelectronic devices realized to date, UV/blue LED and UV-sensors based on transparent pn junction and high performance transparent TFT using n-type TCO as an n-channel. Finally, unique optoelectronic properties (p-type degenerate conduction, transfer doping of carriers, RT-stable exciton, and large optical nonlinearity) originating from 2D-electronic nature in p-type layered oxychalcogenides are summarized along with the fabrication method of epitaxial thin films of these materials.     

聚苯胺导电聚合物应用新进展

简单介绍了近年来聚苯胺导电材料的研究进展及应用现状,指出了聚苯胺在应用中存在的一些问题,并展望了聚苯胺导电材料今后的发展方向和应用前景.     

Recent progress and challenges on two-dimensional material photodetectors from the perspective of advanced characterization technologies

Nano Research - Atomically thin two-dimensional (2D) materials exhibit enormous potential in photodetectors because of novel and extraordinary properties, such as passivated surfaces, tunable...     

多孔金属流场双极板研究进展

多孔金属是一种兼具结构与功能的材料,得益于其低密度、高孔隙率、可控渗透性的优点,在许多领域都有广泛应用。本文综述了多孔金属在质子交换膜燃料电池(proton exchange membrane fuel cell,PEMFC)双极板流场中的研究进展,相较于传统流道流场,高开孔率(>70%)的多孔金属具有相互连通的三维立体结构,可以增加气体分布均匀性、并加强气体传质、增强电子和热的传导及水的排出,从而对电池性能有较大提升。同时探讨多孔金属参数、流场结构设计、服役参数目和多孔材料本身对多孔金属流场在PEMFC应用中的影响。目前阻碍多孔金属在PEMFC应用的最大问题是腐蚀,且多孔金属内部结构复杂对涂层制备工艺提出更大挑战,因此如何有效解决多孔金属在PEMFC两极环境中的腐蚀问题,对推进多孔金属在燃料电池领域中的应用意义重大。     

Strongly enhanced electromechanical coupling in atomically thin transition metal dichalcogenides

Flexoelectricity in thin films has emerged as an effective electromechanical response owing to appealing scaling law and universal existence. However, current studies show limited out-of-plane converse flexoelectric effect (CFE) of ultra-thin transition metal dichalcogenides (TMDs) when compared to their conventional in-plane piezoresponse. Here, we report converse flexoresponse of atomically thin TMDs such as molybdenum disulfide (MoS₂) and tungsten diselenide (WSe₂) which exceeds their intrinsic in-plane piezoresponses. Our piezoresponse force microscopy (PFM) measurements revealed strongly enhanced CFE of the atomically thin MoS₂ and WSe₂ than their bulk counterpart (∼700% enhancement in MoS₂, ∼400% enhancement in WSe₂). We observed an anomalous reduction in converse flexoresponse in the monolayer structure attributed to a puckering deformation. By inducing a built-in in-plane tension to reduce puckering, we estimated the CFE of monolayer WSe₂ to be 8.14 pm/V, the highest among the atomically thin TMDs.     

Recent progress in ALEGRA development and application to ballistic impacts

ALEGRA is a multi-material, arbitrary-Lagrangian-Eulerian (ALE) code for solid dynamics being developed by the Computational Physics Research and Development Department at Sandia National Laboratories. It combines the features of modern Eulerian shock codes, such as CTH, with modern Lagrangian structural analysis codes. With the ALE algorithm, the mesh can be stationary (Eulerian) with the material flowing through the mesh, the mesh can move with the material (Lagrangian) so there is no flow between elements, or the mesh motion can be entirely independent of the material motion (Arbitrary). All three mesh types can coexist in the same problem, and any mesh may change its type during the calculation. In this paper we summarize several key capabilities that have recently been added to the code or are currently being implemented. As a demonstration of the capabilities of ALEGRA, we have applied it to the experimental data taken by Silsby.     

Exploration of channel width scaling and edge states in transition metal dichalcogenides

We explore the impact of edge states in three types of transition metal dichalcogenides (TMDs), namely metallic Td-phase WTe₂ and semiconducting 2H-phase MoTe₂ and MoS₂, by patterning thin flakes into ribbons with varying channel widths. No obvious charge depletion at the edges is observed for any of these three materials, in contrast to observations made for graphene nanoribbon devices. The semiconducting ribbons are characterized in a three-terminal field-effect transistor (FET) geometry. In addition, two ribbon array designs have been carefully investigated and found to exhibit current levels higher than those observed for conventional one-channel devices. Our results suggest that device structures incorporating a high number of edges can improve the performance of TMD FETs. This improvement is attributed to a higher local electric field, resulting from the edges, increasing the effective number of charge carriers, and the absence of any detrimental edge-related scattering.

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含磷聚硅氧烷的制备及应用研究进展

含磷聚硅氧烷是逐渐兴起的一种新型高分子材料,属于元素改性有机硅高分子的范畴,是近年来研究的热点之一。含磷聚硅氧烷由于兼具有机磷化合物阻燃和有机硅高分子材料热稳定性好、无卤环保等优点,将会在有机高分子材料的阻燃应用领域发挥重要作用。就近年来含磷聚硅氧烷合成方法、阻燃应用两方面的研究进展进行综述,并对含磷聚硅氧烷的研究重点和发展方向进行了展望。     

磁性金属有机复合材料的合成与应用

金属有机框架材料(MOFs)是一种将金属离子中心与有机配体通过配位键结合起来的一类具有网格结构的材料。由于金属离子以及有机配体的多样性,MOFs的结构也具有多样性。磁性金属有机复合材料是一种新型的复合材料,既结合了MOFs的网状结构及结构多变性的优点,又结合了磁性材料易于分离且可重复利用的特性,使得这种材料在药物载体、多相催化、选择吸附等多种方面都有着较为广泛的应用。以经典的几类MOFs为分类依据,研究了它们与磁性材料结合形成新型复合材料的方法,同时概括了这些新型复合材料在不同领域的应用,最后提出了该材料目前所存在的问题,并对今后的研究方向进行了展望。     

3D-to-2D phase transformation through highly ordered 1D crystals from transition-metal oxides to dichalcogenides

Although solid-state phase transformations through chemical reaction with the surrounding environment are important in the field of materials science, the atomic-level dynamics at reacting surfaces have been difficult to observe directly. Herein, we found highly ordered arrays of 1D intermediate crystals with a unique atomic configuration during the thermal sulfidation of 3D-structured MoO₂ to 2D layer-structured MoS₂. These arrays reveal a dimension-breaking reconstruction process (3D → 1D → 2D) as well as a unique electronic structure evolution. Theoretical calculations show that the 1D crystals have a cross-sectional structure of four transition-metal atoms arranged in a diamond shape; these are critical to the atomic layer-by-layer formation of 2D transition-metal dichalcogenides. Furthermore, electronic structure analyses reveal that the 1D intermediate crystals alter the MoO₂/MoS₂ contact structure from p- to n-type with increases in the number of formed MoS₂ layers.