• 文献标题:   Abnormal blueshift of the absorption edge in graphene nanodots
  • 文献类型:   Article
  • 作  者:   SHENG WD
  • 作者关键词:  
  • 出版物名称:   JOURNAL OF CHEMICAL PHYSICS
  • ISSN:   0021-9606 EI 1089-7690
  • 通讯作者地址:   Fudan Univ
  • 被引频次:   1
  • DOI:   10.1063/1.5030756
  • 出版年:   2018

▎ 摘  要

In a conventional semiconductor, when the dielectric screening effect is suppressed, the exciton binding energy increases and the corresponding excitonic transition would exhibit a redshift in the spectrum. In this work, I study the optical properties of hexagonal graphene nanodots by using a configuration interaction approach and reveal that the edge of the absorption spectrum shows an abnormal blueshift as the environmental dielectric constant epsilon(r) decreases. The two dominant many-body effects in the nanodot: the quasiparticle and excitonic effects are both found to scale almost linearly with epsilon(-1)(r). The former is shown to have a larger proportionality constant and thus accounts for the blueshift of the absorption edge. In contrast to the long-range Coulomb interaction, the on-site Coulomb energy is found to have a negative impact on the bright excitonic states. In the presence of a strong dielectric screening effect, a strong short-range Coulomb interaction is revealed to be responsible for the disintegration of the bright exciton. Published by AIP Publishing.