Green Phosphorene Research Articles

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

Most recently, a phosphorus allotrope called green phosphorus has been predicted, which has a direct bandgap 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 were investigated. Remarkably, we found 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 that the Young's modulus and Poisson's ratio in the zigzag direction are four times larger than those in the armchair direction, which confirms the anisotropy of the material. Furthermore, the uniaxial strain can trigger the direct-indirect bandgap transition for green phosphorene, and the critical strains for the bandgap transition are revealed.

Prediction of Green Phosphorus with Tunable Direct Band Gap and High Mobility.

Black phosphorus is an emerging material in nanoelectronics and nanophotonics due to its high carrier mobility and anisotropic in-plane properties. In addition, the polymorphism of phosphorus leads to numerous searches for new allotropes that are more attractive than black phosphorus in a variety of applications. On the basis of ab initio evolutionary crystal structure search computation, we report the prediction of a phosphorus allotrope called green phosphorus (λ-P), which exhibits direct band gaps ranging from 0.7 to 2.4 eV and strong anisotropy in optical and transport properties. Free-energy calculations show that a single-layer form, termed green phosphorene, is energetically more stable than blue phosphorene, and a phase transition from black to green phosphorene can occur at temperatures above 87 K. We suggest that green phosphorene can be synthesized on corrugated metal surfaces rather than clean surfaces due to its buckled structure, providing guidance to achieving epitaxial growth.