# Nonmonotonic band gap evolution in bent phosphorene nanosheets

## TL;DR

This study reveals that bending phosphorene nanosheets causes nonmonotonic changes in their electronic properties, with significant band gap variations depending on curvature and bending direction, as shown by advanced many-body perturbation calculations.

## Contribution

It demonstrates for the first time that slight curvature in phosphorene nanosheets leads to substantial and nonmonotonic band gap changes, including a transition from direct to indirect band gap.

## Key findings

- Band gap varies nonmonotonically with bending curvature.
- Bending can change the band gap from direct to indirect.
- Band gap modulation can reach up to 0.7 eV depending on bending direction.

## Abstract

Nonmonotonic bending-induced changes of fundamental band gaps and quasiparticle energies are observed for realistic nanoscale phosphorene nanosheets. Calculations using stochastic many-body perturbation theory (sGW) show that even slight curvature causes significant changes in the electronic properties. For small bending radii (< 4 nm) the band-gap changes from direct to indirect. The response of phosphorene to deformation is strongly anisotropic (different for zig-zag vs. armchair bending) due to an interplay of exchange and correlation effects. Overall, our results show that fundamental band gaps of phosphorene sheets can be manipulated by as much as 0.7 eV depending on the bending direction.