Open AccessTransition in nanoscale electrical conductivity in the Langmuir-Blodgett film of a novel liquid crystalline oligomer
Author(s) -
Bharat Kumar,
K. A. Suresh,
Hari Krishna Bisoyi,
Sandeep Kumar
Publication year - 2020
Publication title -
nano express
Language(s) - English
Resource type - Journals
ISSN - 2632-959X
DOI - 10.1088/2632-959x/ab79ff
Subject(s) - monolayer , materials science , triphenylene , langmuir–blodgett film , substrate (aquarium) , scanning tunneling microscope , alkyl , molecule , crystallography , nanotechnology , chemistry , liquid crystal , organic chemistry , optoelectronics , oceanography , geology
We have studied the nanoscale electrical conductivity of a monolayer film of a novel star shaped liquid crystalline molecule, hexatriphenylene substituted anthraquinone (AQD6). The molecule has a central core of electron deficient anthraquinone moiety connected to six electron rich triphenylene moieties by flexible alkyl chains. The monolayer formed at air-water interface was transferred onto the solid substrates by Langmuir-Blodgett (LB) technique and its surface topography was imaged using an atomic force microscope (AFM). The limiting area obtained from the surface pressure-area per molecule isotherm and the topography of the AFM images suggest that the anthraquinone moiety of the AQD6 molecule is organized in face-on configuration on the substrate and the triphenylene moieties are in edge-on configuration extended away from the substrate. We have studied the electrical conductivity of the AQD6 monolayer deposited on gold coated silicon substrate using a current sensing AFM. Analysis of current ( I ) − voltage ( V ) characteristics of the metal-monolayer film-metal junction showed a transition from direct tunneling to an injection tunneling. Further, we have estimated the barrier height and the effective mass of electron in the metal-monolayer film-metal junction.