Strain modulation of the exciton anisotropy and carrier lifetime in black phosphorene

Manipulating excitons is of great significance to explore the optical properties of 2D materials. In this work, we investigate the excitonic properties and carrier dynamics of bilayer black phosphorene by imposing in-plane biaxial strain. The results show that the strain can modulate not only the contribution of the excitons to optical absorption but also the anisotropic shape of the first exciton. This can be ascribed to the strain effect on the band realignment as well as to changes of the parity and the electron effective mass at the CBM. At the temperature of 300 K, a 3% strain reduces the non-adiabatic coupling between the VBM and CBM and then increases the carrier lifetime by a factor of 13, and the results can be used to estimate the strain effect on the excitonic lifetime. Our results demonstrate that manipulation of the biaxial strain is a promising strategy to modulate the exciton properties of black phosphorene.