Giant Stark Effect in Two-Dimensional Hittorf?s Phosphorene

The electric field tunable band gap and optical properties in low-dimensional materials (quantum confined Stark effect) are very useful in applications of optoelectronics. In this paper, based on the many-body perturbation method, we investigate the evolution of the quasiparticle electronic structure, exciton, and optical properties of two-dimensional (2D) Hittorf???s phosphorene under an out-of-plane electric field. Compared to other 2D monolayers, the relatively large thickness of Hittorf???s phosphorene leads to a significant reduction in the quasiparticle band gap when an electric field is applied along the quantum confinement direction. The unique bilayer structure, on the other hand, guarantees a well spatial separation of photon-excited electron-hole pairs and, consequently, reduced exciton binding energy under an out-of plane electric field. These combined effects lead to an almost fixed exciton energy and optical absorption edge at low applied electric fields. However, when the field is larger than 0.1 V/??, substantial reductions in the exciton energy and optical absorption edge are identified. For the higher-order exciton states, the involvement of more complex band-to-band electron-hole pair formation results in a nonmonotonic electric field dependence. The effective optical modulation accompanied with these giant Stark effects shows potential applications of Hittorf???s phosphorene in 2D optoelectronic devices.

Automated summary

This paper investigates the evolution of the quasiparticle electronic structure, exciton, and optical properties of two-dimensional Hittorf's phosphorene under an electric field. The results show that the exciton energy and optical absorption edge of Hittorf's phosphorene remain almost unchanged at low applied electric fields, but significantly decrease when the electric field exceeds 0.1 V/??.