Professor Chen's work on Tuning Band Gaps of BN Nanosheets and Nanoribbons was featured as journal cover of Nanoscale

01/26/ 2015

Together with his collaborator, Professor Zhen Zhou (Nankai University, China) and other coworkers, Professor Chen introduced a new approach to tune the band gaps of boron nitride nanosheets and nanoribbons.

The hexagonal BN (h-BN) is the nearest isostructural analogue of graphene. In contrast to the semi-metallic graphene, h-BN materials, in planar sheet-like or ribbon-like form, are highly insulating, which is a severe obstacle to apply BN to electronic devices. It is thus of great demand to explore an easy and controllable method to modify the electronic properties of BN graphene.

Chen and coworkers performed systematic DFT computations to study the dihalogen interactions and their effect on band structures in halogenated (fluorinated and chlorinated) BN bilayers and the aligned halogen-passivated zigzag BN nanoribbons (BNNRs).  Dihalogen bonding (halogen-halogen interaction) is an emerging non-covalent interaction that occurs between two halogen atoms. The halogens X participated in dihalogen bonding typically include F, Cl, Br, and I, and the strength of X…X interaction increases with the general trend of F < Cl < Br < I. Dihalogen bonds occur due to the polarization of halogen atoms.

Chen’s team demonstrated that considerable homo-halogen (FF and ClCl) interactions exist in fluoro (chloro)-BN bilayer (aligned ribbons), and substantial hetero-halogen (FCl) interactions are available in hybrid fluor-BN/chloro-BN bilayer (aligned hybrid ribbons), and these dihalogen interactions at the 2D or 1D interfaces lead to significant band-gap reduction for the interactive BN nanosystems, and their binding strengths and electronic properties can be further controlled by applying an external electric field, wherein an extensive modulation from large- to medium-band-gap semiconductors, or even metals can be realized by simply adjusting the direction and strength of the applied electric field.

This work offers insightful prospects to flexibly tune the large bandgap of BN nanosystems, which would facilitate the design and application of BN materials in next-generation nanoelectronic devices. This finding is highlighted as a journal cover.

For more details, please refer to!divAbstract

Tuning Band Gaps of BN Nanosheets and Nanoribbons via Interfacial Dihalogen Bonding and External Electric Field

Qing Tang, Jie Bao, Yafei Li, Zhen Zhou*, Zhongfang Chen*

Nanoscale 20146, 8624-8634.