Jump to main content
Jump to site search


Excited State Dynamics Study of the Self-Trapped Exciton Formation in Silicon Nanosheets

Abstract

The exciton formation dynamics of several model silicon nanosheets (SiNSs) are investigated using a time-dependent density functional tight binding method. The first excited (S1) state self-trapped exciton formation in the Si NSs is obtained by observing the frontier orbital localization relating to the characteristic size of the electronic excitations. The frontier molecular orbitals are highly localized in S1 state on the stretched Si-Si bond due to the photo-excited structural relaxation, leading to a significant Stokes shift. Time domain study of the photo-excited emission gap correlated with the frontier orbital localization properties for exciton formation. Stretched Si-Si softer bonds provide a favorable site for exciton localization, resulting in exciton trapping. The exciton formation time found to be around ~450—850 fs showing the consistency of the initial exciton formation time with a recent measurement (~500 to ~900 fs). This study reveals that Si-Si bond breaking act as the optical activity center and provides regulation of the self-trapped exciton formation time by quantum confinement effect in SiNSs; significant to the Si nanomaterial properties.

Back to tab navigation

Supplementary files

Publication details

The article was received on 28 Jul 2018, accepted on 25 Oct 2018 and first published on 29 Oct 2018


Article type: Paper
DOI: 10.1039/C8CP04806A
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
  •   Request permissions

    Excited State Dynamics Study of the Self-Trapped Exciton Formation in Silicon Nanosheets

    N. Ullah, S. Chen and R. Zhang, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP04806A

Search articles by author

Spotlight

Advertisements