Superior mechanical flexibility and strained-engineered direct-indirect band gap transition of green phosphorene

TL;DR

This study explores green phosphorene's mechanical resilience and how uniaxial strain can induce a transition between direct and indirect band gaps, highlighting its potential for flexible electronic applications.

Contribution

It provides the first detailed analysis of green phosphorene's mechanical properties and strain-induced electronic band gap transitions, revealing its high strain tolerance and anisotropic behavior.

Findings

Green phosphorene can sustain up to 35% tensile strain in the armchair direction.

The material exhibits significant anisotropy with Young's modulus and Poisson's ratio four times larger in zigzag direction.

Uniaxial strain can induce direct-indirect band gap transitions at specific critical strains.

Abstract

Most recently, a brand new phosphorus allotrope called green phosphorus has been predicted, which has a direct band gap up to 2.4 eV, and its single-layer form termed green phosphorene shows high stability. Here the mechanical properties and the uniaxial strain effect on the electronic band structure of green phosphorene along two perpendicular in-plane directions are investigated. Remarkably, we find that this material can sustain a tensile strain in the armchair direction up to a threshold of 35\% which is larger than that of black phosphorene, suggesting that green phosphorene is more puckered. Our calculations also show the Young's modulus and Poisson's ratio in the zigzag direction are four times larger than those in the armchair direction, which confirm the anisotropy of the material. Furthermore, the uniaxial strain can trigger the direct-indirect band gap transition for green phosphorene and the critical strains for the band gap transition are revealed.