Stability And Electronic Structure Of One-Dimensional Phosphorene Nanomaterials

Rolling up two-dimensional(2D)materials into nanoscrolls could not only retain the excellent properties of their 2D hosts but also display intriguing physical and chemical properties that arise from their 1D tubular structures.Graphene-based nanoscrolls have already demonstrated the possibility of applications in various fields as advanced 1D functional materials.Recently,the Mo S₂nanoscrolls have also been realized and proved to have properties attractive for potential applications.Here,we focus on phosphorene,by rolling up phosphorene into nanoscrolls with different sizes and chirality,we systematically researched their stability and electronic properties.Our ab initio calculations were performed within the framework of density functional theory(DFT)and the conclusions are listed as followed:(1)Stability and Electronic Strcture of Black Phosphorus Nanoscrolls.Since black phosphorus(BP)was discovered as a new 2D material,it has attracted worldwide interests due to its distinguished electronic properties.Our study reveals that the BP nanoscrolls(BPNSs)are energetically more favorable than monolayer BPs and BP nanotubes(BPNTs),indicating an exothermic nucleation of a scroll.The ab initio molecular dynamics(AIMD)simulations further confirm their thermal stability under room temperature.BPNSs are all semiconductors with a direct band gap,and the band gap can be tuned by adjusting either the radius or width.Moreover,the hole mobility of double-layer BPNS is approximately 20-fold greater than that of a 2D BP sheet.Their unique self-encapsulation structure and layer-dependent conduction band minimum can largely prevent the entrance of O₂ and the production of O₂^-and thereby suppress the possible environmental degradation as well.The enhanced intrinsic stability and promoted electronic properties render BPNSs great promise in many advanced electronics or optoelectronics applications.(2)Stability and Carrier Mobility of Blue Phosphorene Nanoscroll with Different Chirality.As an allotrope of black phosphorous,blue phosphorene(b P)has gained significant attention since it was predicted to be a semiconductor and the direct growth of b P has been realized through molecular beam epitaxy(MBE)in 2016.However,b P strongly interacts with its growth substrate and the following transfer process for application becomes a great challenge.In order to overcome the transfer limits,based on the ab initio electronic structure calculations and the molecular dynamic simulations,self-encapsulated blue phosphorene nanoscrolls(b PNSs)formed by rolling up 2D b P are found to be energetically favorable and thermally stable at room temperature based on ab initio calculations and the molecular dynamic simulations.Moreover,these quasi one-dimensional b PNSs are all semiconductors with wide-range band gaps varying from 0.02?1.8 e V for different scroll thickness and rolling directions.Particularly,the electron mobility reaches as high as 6620 cm²V^-1s^-1 in armchair double-layer b PNSs,which is approximately 20-fold greater than that of 2D b P monolayer.This study discovers the b PNSs as a new class of novel semiconductors and proposes the scrolling strategy as an excellent candidate for the application of other 2D materials.