Optical Transitions and Localized Edge States in Skewed Phosphorene Nanoribbons

TL;DR

This paper investigates how skewed-zigzag phosphorene nanoribbons exhibit tunable bandgaps and localized edge states under electric fields, revealing potential for novel electronic and optical device applications.

Contribution

It introduces a method using DFT-derived tight-binding parameters and Green's function techniques to analyze electric field effects on phosphorene nanoribbons, highlighting tunable electronic properties.

Findings

Nanoribbons show large, tunable bandgaps under electric fields.

Mid-gap states can be localized or metallic depending on field direction.

Bandgap and optical transition properties depend on band edge symmetry.

Abstract

Using the Tight Binding (TB) parameters extracted from Density Functional Theory (DFT) and Recursive Green's Function method, it is shown that skewed-zigzag black phosphorous (phosphorene) nanoribbons obtain large and tuneable bandgap in response to vertical and transverse electric fields. Depending on the direction of the applied field the mid-gap states could possess the localized or metallic nature i.e. non-zero mid-gap density of states. Adjustability of the bandgap and optical dipole transition matrix elements are explained based on the symmetry of involved band edge states. This promises new electronic and optical devices based on phosphorene nanoribbons.