Structure-electronics relations of discotic liquid crystals from a molecular modelling perspective

ABSTRACT

Discotic liquid crystals (DLCs) have been researched for their potential in electronics applications, such as organic field-effect transistors, organic light-emitting diodes and organic photovoltaics. These molecules generally comprise a rigid planar core surrounded by aliphatic chains, and self-organise into columnar phases. Charge transfer is enabled along these columns, as the spatial overlap of the stacked π orbitals within the columns lead to a quasi-one-dimensional conductivity. An understanding of charge transfer and electronics orbitals in the field of DLCs is valuable for rational design of future DLC molecules in electronics applications. This paper provides a perspective that a range of molecular modelling tools may bring into our understanding on the structure, dynamics and electronics properties of DLCs. Whilst the description of charge transfer of DLCs has been substantially investigated, the understanding on the molecular orbitals had been relatively less explored. We introduce a multiscale molecular mechanics and quantum mechanics approach to understanding the relationship between the bandgap and density of states (DOS) and the structural parameters of a DLC. This investigation is expected to be the starting point for situations where knowledge of DOS for DLCs are of the essence, in applications such as current rectification and thermoelectricity.

GRAPHICAL ABSTRACT

KEYWORDS:

• Discotic liquid crystals
• molecular modelling
• charge transport
• charge mobility
• density of states

Acknowledgement

Special thanks to Dr. Abhijit Chatterjee of BIOVIA for useful discussion on DFT molecular approach. This work was supported by the University of Malaya−Ministry of Higher Education Grant under Grant UM.C/1/625/HIR/MOHE/ENG/29; Science Fund under Grant SF-020-2013; Fundamental Research Grant Scheme (FRGS) under Grant FP011-2014A; and Universiti Malaya Research Grant (UMRG) under Grant RP023A-13AET.

Disclosure statement

No potential conflict of interest was reported by the authors.