Edge termination plays a vital role in determining the properties of 2D materials. By performing compelling ab initio simulations, a lowest-energy U-edge [ZZ(U)] reconstruction is revealed in the bilayer phosphorene. Such reconstruction reduces 60% edge energy compared with the pristine one and occurs almost without energy barrier, implying it should be the dominating edge in reality. The electronic band structure of phosphorene nanoribbon with such reconstruction resembles that of intrinsic 2D layer, exhibiting nearly edgeless band characteristics. Although ZZ(U) changes the topology of phosphorene nanoribbon (PNR), simulated TEM, STEM and STM images indicates it is very hard to be identified. One possible identify method is IR/Raman analyses because ZZ(U) edge alters vibrational modes dramatically. Beyond, it also increases the thermal conductivity of PNR 1.4 and 2.3 times than the pristine and Klein edges.
We have assessed mechanical bending as a powerful controlling tool for the electronic structure and optical properties of phosphorene nanoribbons. We use state-of-the-art density functional approximations in our work. The overall performance of the recently developed meta-generalized gradient approximation (meta-GGA) mTASK [Phys. Rev. Mater. \textbf{5}, 063803 (2021)] functional establishes the method as a useful alternative to the screened hybrid HSE06 for better band gaps of phosphorene nanoribbons. We present a detailed and novel analysis to interpret the optical absorption of bent phosphor…
A few-layer black phosphorene has recently gained significant interest in the scientific community. In this paper, we consider several polymorphs of phosphorene nanoribbons (PNRs) and employ deformation potential theory within the effective mass approximation together with density functional theory to investigate their structural, mechanical and electronic properties. The results show that stability of PNRs strongly depends on the direction along which they can be cut from 2D counterpart. PNRs also exhibit a wide range of line stiffness ranging from 6x10^10 eV/m to 18x10^11 eV/m which has litt…
We have explored the possibility of using low dimensional phosphorene based nanoscale device for the detection of nitroaromatic based explosives. In this work, we have investigated the structural, electronic, adsorption, and quantum transport properties of phosphorene nanoribbon APNR in the presence of different nitroaromatic compounds NACs using the state-of-the-art first principle density functional theory DFT calculations. Our results reveal that the adsorption of explosive molecules is far from the APNR surface, which neither affects the structure of the explosive molecule nor the APNR sur…
We theoretically investigate the thermoelectric properties of zigzag bilayer phosphorene nanoribbons (ZBPNR). We first, draw an analogy between the extended Su-Schrieffer-Heeger (SSH) ladder and ZBPNR edge states and obtain their corresponding band structure and wave functions analytically. Then, by applying the energy filtering method, we show that the electric power and thermoelectric efficiency of the ZBPNRs can be improved remarkably in the presence of mid-gap edge states. We also argue how to engineer the edge modes to further optimize thermoelectric power and efficiency of the system by …
Phosphorene is an anisotropic puckered two-dimensional ($2$D) hexagonal lattice of phosphorus atoms. The edge modes in a zigzag phosphorene nanoribbon (ZPNR) are quasi-flat in nature and fully isolated from the bulk states, which are unique in comparison to the other hexagonal lattices like graphene, silicene etc. We theoretically investigate the Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange interaction between two magnetic impurities placed on the nanoribbon, and extract the signatures of the flat edge states via the behavior of it. Due to the complete separation of the edge states from the b…
Transport of the edge-state electrons along zigzag phosphorene nanoribbons in presence of two impurities/vacancies is analytically investigated. Considering the places of the defects, a number of different situations are examined. When both defects are placed on the edge zigzag chain, as is expected, with changing the energy of the traveling electrons the electrical conductance exhibits a resonance behavior. In this case, for two vacancies the observed resonant peaks become extremely sharp. An amazing behavior is seen when the second vacancy is located along an armchair chain while the first i…
The effects of lattice distortion and chemical disorder on charge transport properties of two-terminal zigzag phosphorene nanoribbons (zPNRs), which shows resonant tunneling behavior under an electrical applied bias, are studied. Our comprehensive study is based on an {\it ab~initio} quantum transport calculations on the basis of the Landauer theory. We use nitrogen and silicon substitutional dopant atoms, and employ different physical quantities such as $I-V$ curve, voltage drop behavior, transmission spectrum, transmission pathway, and atomic current, to explore the transport mechanism of zP…
Zigzag phosphorene nanoribbons have quasi-flat band edge modes entirely detached from the bulk states. We analytically study the electronic transport through such edge states in the presence of a localized defect for semi-infinite and finite ribbons. Using the tight-binding model, we derive analytical expressions for the Green's function and transmission amplitude of both pristine and defective nanoribbons. We find that the transmission of both semi-infinite and finite ribbons is sensitive to the location of a single impurity defect with respect to the edge. By the presence of an impurity on t…
In recent years, single element two-dimensional atom crystal materials have aroused extensive interest in many applications. Blue phosphorus, successfully synthesized on Au substrate by molecular beam epitaxy not long ago, shows unusual geometrical and electronic structures. We investigate the electronic structures and transport properties of zigzag blue phosphorene nanoribbons by using a first-principles method, which can be obviously tuned via different groups passivation on the both edges. The ZBPNRs-H and ZBPNRs-OH present a wide gap semiconductor property. While the ZBPNRs-O are metallic.…
It is known that there is a wide class of quasi-two-dimensional graphenelike nanomaterials which in many respects can outperform graphene. So, here in addition to graphene, the attention is directed to stanene (buckled honeycomb structure) and phosphorene (puckered honeycomb structure). It is shown that, depending on the doping, these materials can have magnetically ordered edges. Computed diagrams of magnetic phases illustrate that, on the one hand, n-type doped narrow zigzag nanoribbons of graphene and stanene have antiferromagnetically aligned magnetic moments between the edges. On the othe…
In this work, we present a systematic first-principles density-functional theory based study of geometry, electronic structure, and optical properties of armchair phosphorene nanoribbons (APNRs), with the aim of understanding the influence of edge passivation. Ribbons of width ranging from 0.33 nm to 3.8 nm were considered, with their edges functionalized with the groups H, OH, F, Cl, S, and Se. The geometries of various APNRs were optimized, and the stability was checked by calculating their formation energies. Using the relaxed geometries, calculations of their band structure and optical pro…
For the pristine phosphorene nanoribbons (PNRs) with edge states, there exist two categories of edge bands near the Fermi energy (EF), i.e., the shuttle-shaped twofold-degenerate and the near-flat simple degenerate edge bands. However, the usual experimental measurement may not distinguish the difference between the two categories of edge bands. Here we study the varying rule for the edge bands of PNRs under an external electrostatic field. By using the KWANT code based on the tight-binding approach, we find that the twofold-degenerate edge bands can be divided into two separated shuttles unti…
The Seebeck coefficient is an important quantity in determining the thermoelectric efficiency of a material. Phosphorene is a two-dimensional material with a puckered structure, which makes its properties anisotropic. In this work, a phosphorene nanodisk (PDisk) with a radius of 3.1 nm connected to two zigzag phosphorene nanoribbons is studied, numerically, by the tight-binding (TB) and non-equilibrium Greens function (NEGF) methods in the presence of transverse and perpendicular electric fields. Our results show that the change of the structure from a zigzag ribbon form to a disk one creates …
Two-dimensional (2D) crystals' edge structures not only influence their overall properties but also dictate their formation due to edge-mediated synthesis and etching processes. Edges must be carefully examined because they often display complex, unexpected features at the atomic scale, such as reconstruction, functionalization, and uncontrolled contamination. Here, we examine atomic-scale edge structures and uncover reconstruction behavior in bilayer phosphorene. We use in situ transmission electron microscopy (TEM) of phosphorene/graphene specimens at elevated temperatures to minimize surfac…
The central question in the field of 2D materials is how a material behaves when it is patterned at nanometer scale with different edge geometries. Due to the anisotropy inherent in the puckered structure, black phosphorene nanostructures may have more varieties of edge geometries. Here, we present a comprehensive 2D planar crystallographic characterization of phosphorene uniformly by a chiral vector (angle), from which a new type of edge atomic configuration, the slope edge geometry is discovered. The phosphorene nanoribbons (PNRs) with slope edges, like previously noticed zigzag and skewed-a…
Atomic-scale imaging of graphene nanoribbons on graphene after polymer-free substrate transfer
Universidad de Granada（格拉纳达大学）；The Pennsylvania State University（宾夕法尼亚州立大学）；Max Planck Institute for Polymer Research（马克斯·普朗克聚合物研究所）；University of Bern（伯尔尼大学）；Johannes Gutenberg University Mainz（美因茨约翰内斯·古腾堡大学）
