Solution phase growth and analysis of super-thin zigzag tin selenide nanoribbons

Tin selenide (SnSe), a highly promising layered material, has been garnering particular interest in recent times due to its significant promise for future energy devices. Herein we report a simple solution phase approach for growing highly crystalline layered SnSe nanoribbons. Polyvinylpyrrolidone (PVP) was used as a templating agent to selectively passivates the (100) and (001) facets of the SnSe nanoribbons resulting in the unique growth of nanoribbons along their b-axis with a defined zigzag edge state along the sidewalls. The SnSe nanoribbons are few layers thick (~ 20 layers), with mean widths of ~40 nm, and achievable length of > 1 m. Nanoribbons could be produced in relatively high quantities (>150 mg) in a single batch experiment. The PVP coating also offer some resistance to oxidation, with removal of the PVP seen to lead to the formation a SnSe/SnOx core shell structure. The use of non-toxic PVP to replace toxic amines that are typically employed for other 1D forms of SnSe is a significant advantage for sustainable and environmentally friendly applications. Heat transport properties of the SnSe nanoribbons, derived from power dependent Raman spectroscopy, demonstrate the potential of SnSe nanoribbons as thermoelectric material.

Spin State Switching in Heptauthrene Nanostructure by Electric Field: Computational Study

Recent experimental studies proved the presence of the triplet spin state in atomically precise heptauthrene nanostructure of nanographene type (composed of two interconnected triangles with zigzag edge). In the paper, we report the computational study predicting the possibility of controlling this spin state with an external in-plane electric field by causing the spin switching. We construct and discuss the ground state magnetic phase diagram involving S=1 (triplet) state, S=0 antiferromagnetic state and non-magnetic state and predict the switching possibility with the critical electric field of the order of 0.1 V/Å. We discuss the spin distribution across the nanostructure, finding its concentration along the longest zigzag edge. To model our system of interest, we use the mean-field Hubbard Hamiltonian, taking into account the in-plane external electric field as well as the in-plane magnetic field (in a form of the exchange field from the substrate). We also assess the effect of uniaxial strain on the magnetic phase diagram.

Electronic Properties of Graphene Nanoribbons Doped with Pyrrole-Like Nitrogen

Doping of graphene nanoribbons with various chemical elements leads to a change in their band structure, which significantly expands the range of applications of these objects in modern electronic devices. In this work, the authors investigate graphene nanoribbons of the «armchair» and «zigzag» types with different concentrations of pyrrole-like nitrogen at the edges. The SCC-DFTB method was used to establish the most energetically favorable configurations of pyrrole-like nitrogen at each edge of graphene nanoribbons. The relationship between the energy gaps of graphene nanoribbons and the content of the considered functional nitrogen-containing groups in them was determined. Calculations have shown that, by incorporating into the atomic lattice, pyrrole-like nitrogen at the «zigzag» edge transfers a greater amount of charge to nearby carbon atoms, which makes such nanoribbons more chemically active in comparison with «armchair» type nanoribbons. Nitrogen doped «zigzag» graphene nanoribbons may be a promising chemoresistive element of nanosensors; however, these conclusions require further calculations.

Transport of Topological Edge States in 2D Zigzag Edge Tungsten Ditelluride Nanoribbon

In this paper, we have investigated the transport of topological edge states in 2D Zigzag edge Tungsten Ditelluride Nanoribbon (ZTDNR).We have found that zigzag edge nanoribbon (NR) of Tungsten Ditelluride develops topological edge states in the presence of intrinsic spin orbit interaction (SOC). We have used three band tight binding model for the electrons of dz2 , dxy, and dx2 - y2 orbitals with SOC for calculating band structure of NR and Non Equilibrium Greens Function (NEGF) formalism for transport in the NR. We have investigated transport in a pristine device, transport in the presence of a finite potential barrier, transport with constriction within the device and transport with edge imperfections.