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Excitonic ground states in phosphorene nanoflakes
Jun Zhong1, Wenzhuo Huang1, Weidong Sheng1
1State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China. shengw@fudan.edu.cn.
Physical Chemistry Chemical Physics : PCCP
|August 8, 2023
Summary
An electric field can induce a biexcitonic ground state in phosphorene nanoflakes, altering their electronic and optical properties. This transition enhances electron-hole correlation, leading to unique optical anisotropy.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Chemistry
Background:
- Phosphorene, a 2D material, exhibits unique electronic and optical properties.
- Understanding excitonic effects in low-dimensional nanostructures is crucial for novel electronic applications.
- Exciton-exciton interactions are typically studied within independent multiexciton frameworks.
Purpose of the Study:
- To investigate the possibility of an excitonic ground state in phosphorene nanoflakes under an in-plane electric field.
- To analyze the transition of the ground state from electronic to biexcitonic with varying electric field strength and screening effects.
- To explore the impact of a biexcitonic ground state on the optical properties of phosphorene nanoflakes.
Main Methods:
- Configuration-interaction approach beyond independent multiexcitons.
- Computational modeling of phosphorene nanoflakes.
- Analysis of ground state energy transitions with applied electric fields and screening variations.
Main Results:
- Prediction of an excitonic ground state in phosphorene nanoflakes under an in-plane electric field.
- Ground state transitions from electronic to nearly fully biexcitonic with increasing electric field strength (> 0.25 V nm-1).
- Biexcitonic ground state becomes energetically favorable by hundreds of meV.
- Similar ground state transformation observed with varying screening effects (strong to weak).
- Enhanced electron-hole correlation due to electric field and weak screening drives the transition.
- Biexcitonic state exhibits an absorption spectrum with zigzag-polarized transitions, breaking bulk phosphorene's optical anisotropy.
Conclusions:
- An in-plane electric field can induce a stable biexcitonic ground state in phosphorene nanoflakes.
- Enhanced electron-hole correlation is the key mechanism behind this field-induced transition.
- The biexcitonic state in phosphorene nanoflakes leads to novel optical properties, including altered polarization behavior.
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