Programme

O.9 -- Oral, VCTP-47

Date: Tuesday, 2 August 2022

Time: 16:00 - 16:25

Correlation between energy band transition and optical absorption spectrum in bilayer armchair graphene nanoribbons

Nguyen Lam Thuy Duong (1), Tran Van Truong (2) and Vu Thanh Tra (3)

(1) School of Graduate, Can Tho University, Can Tho, Vietnam (2) IMPMC, Université Pierre et Marie Curie (UPMC), Sorbonne Universit´es, CNRS UMR 7590, IRD, UMR 206, Case 115, 4 place Jussieu, 75252 Paris Cedex 05, France (3) Department of Physics, School of Education, Can Tho University, Can Tho, Vietnam

By utilizing atomistic tight-binding description and the gradient approximation, we studied the correlation between absorption spectra and electronic structures of bilayer and single-layer armchair nanoribbons (BL-AGNRs and SL-AGNRs) without and with external electric fields. The alternations of peak structure, gap size, and charge distribution for three groups 3p, 3p+1, and 3p+2 are examined extensively. The remarkable results are: (i) the position and the height of the 1st peaks in the 3p and 3p+1 groups are found to vary as a function of the number of dimer lines, while those in the 3p+2 group remain unchanged for BL-AGNRs and vanish in the region [0, 0.4t0] for SL-AGNRs; (ii) with the increase of potentials Vt, the red-shift and lowering in the height of the 1st ¬peaks occur for the 3p and 3p+1 groups, meanwhile, addition peaks in the opposite direction are observed for 3p+2 due to the bandgap opening; (iii) the vertical field has a strong impact in modulating the peak structure, meanwhile the transverse field only show its influence on the peak height, especially in the 3p group. Our outcomes provide a more comprehensive understanding of the important role of external electric fields on the optical transition in single-layer and bilayer graphene nanoribbons, and unveil potential applications of these structures in optoelectronics.

Presenter: Nguyen Lam Thuy Duong