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Van der Waals (vdW) heterostructures—in which layered materials are purposely selected to assemble with each other—allow unusual properties and different phenomena to be combined and multifunctional electronics to be created, opening a new chapter for the spread of internet‐of‐things applications. Here, an O2‐ultrasensitive MoTe2 material and an O2‐insensitive SnS2 material are integrated to form a vdW heterostructure, allowing the realization of charge‐polarity control for multioperation‐mode transistors through a simple and effective rapid thermal annealing strategy under dry‐air and vacuum conditions. The charge‐polarity control (i.e., doping and de‐doping processes), which arises owing to the interaction between O2 adsorption/desorption and tellurium defects at the MoTe2 surface, means that the MoTe2/SnS2 heterostructure transistors can reversibly change between unipolar, ambipolar, and anti‐ambipolar transfer characteristics. Based on the dynamic control of the charge‐polarity properties, an inverter, output polarity controllable amplifier, p‐n diode, and ternary‐state logics (NMIN and NMAX gates) are demonstrated, which inspire the development of reversibly multifunctional devices and indicates the potential of 2D materials. [ABSTRACT FROM AUTHOR]

Atomically thin tungsten diselenide (WSe2) transistors with multilayer graphene (w/ G) as contact electrodes are successfully fabricated by a precise area‐controllable chemical vapor deposition method. The performance and electrical properties of the devices are explored. Compared to those of WSe2 transistors without graphene contacts (w/o G), the maximum current densities of the w/ G–WSe2 transistors increase by one to two orders of magnitude. In addition, the device performance is markedly improved for the w/ G–WSe2 transistors, including an on/off current ratio of ≈107, subthreshold swing of ≈150 mV/decade, and threshold voltage of ≈1.75 V. The improved performance of the w/ G–WSe2 transistors is ascribed to the alleviation of electrical contributions from metal–semiconductor contact resistance, which is consistent with the analysis of low‐frequency noise measurements. In addition, self‐trapping behavior in the WSe2 channel is found, which possibly paves a way to further optimize the performance of layered devices. Finally, an inverter using the w/ G–WSe2 transistors is demonstrated. These transistors represent a step forward in the development of layered graphene‐based electronics suitable for energy‐efficient and high‐performance industrial‐scale products. [ABSTRACT FROM AUTHOR]

We describe the preparation of vinyl-terminated benzoxazine-functionalized graphene using free radical grafting. The resulting functionalized graphene (f-graphene) was incorporated into bis(3-allyl-3,4-dihydro- 2H-1,3-benzoxazinyl)methane (V- BF-a) monomer in order that nanocomposites could be prepared. Results of scanning electron microscopy and transmission electron microscopy revealed that the sheets of f-graphene were well dispersed throughout the matrix, and there was a strong interfacial interaction between the f-graphene and polyV-BF-a. The inclusion of f-graphene into the nanocomposites resulted in a material with a high thermal stability and a low coefficient of thermal expansion ( CTE); increasing the content of f-graphene reduced the CTE significantly more. A reduction in the CTE of up to 48% was produced by adding just 1 wt% of f-graphene; this corresponded to an increase of 12 °C in the glass transition temperature. These results suggest that f-graphene nanocomposites can be 'tuned' to give materials with both a low CTE and a high thermal stability, and that graphene composites of this type can thus be manufactured to withstand a wider range of temperatures. [ABSTRACT FROM AUTHOR]

Complementary circuits based on 2D materials show great promise for next‐generation electronics. An ambipolar all‐2D ReSe2 field‐effect transistor (FET) with a hexagonal boron nitride gate dielectric is fabricated and its electronic characteristics are comprehensively studied by temperature dependence and noise measurements. Ambipolar transfer characteristics are achieved owing to the tunable Fermi level of the graphene contact and negligible and 30 meV Schottky barrier heights for the n‐ and p‐channel regimes, respectively. An inverter is also fabricated to demonstrate ambipolar ReSe2 FET operation in a logic circuit. Furthermore, a p/n switchable unipolar FET is designed and shows potential for building complimentary circuits from a signal device. This work demonstrates the potential of all‐2D ReSe2 FETs and makes available new approaches for designing next‐generation devices. [ABSTRACT FROM AUTHOR]

Electronics based on layered indium selenide (InSe) channels exhibit promising carrier mobility and switching characteristics. Here, an InSe tribotronic transistor (denoted as w/In InSe T‐FET) obtained through the vertical combination of an In‐doped InSe transistor and triboelectric nanogenerator is demonstrated. The w/In InSe T‐FET can be operated by adjusting the distance between two triboelectrification layers, which generates a negative electrostatic potential that serves as a gate voltage to tune the charge carrier transport behavior of the InSe channel. Benefiting from the surface charging doping of the In layer, the w/In InSe T‐FET exhibits high reliability and sensitivity with a large on/off current modulation of 106 under a low drain–source voltage of 0.1 V and external frictional force. To demonstrate its function as a power‐saving tactile sensor, the w/In InSe T‐FET is used to sense "INSE" in Morse code and power on a light‐emitting diode. This work reveals the promise of 2D material–based tribotronics for use in nanosensors with low power consumption as well as in intelligent systems. [ABSTRACT FROM AUTHOR]