Controlling the charge state of organic molecule quantum dots in a 2d nanoarray

Dhaneesh Kumar
Lead author Dhaneesh Kumar is a PhD student in Monash School of Physics and Astronomy.

A Monash University study has fabricated a self-assembled, carbon-based nanofilm where the charge state (ie, electronically neutral or positive) can be controlled at the level of individual molecules, on a length scale of around one nanometre.

The atomically-thin nanofilm consists of an ordered two-dimensional (2D) array of molecules which behave as ‘zero dimensional’ entities called quantum dots (QDs).

This system has exciting implications for fields such as computer memory, light-emitting devices and quantum computing.

The School of Physics and Astronomy study shows that a single-component, self-assembled 2D array of the organic (carbon-based) molecule dicyanoanthracene can be synthesised on a metal, such that the charge state of each molecule can be controlled individually via an applied electric field.

“This discovery would enable the fabrication of 2D arrays of individually addressable (switchable) quantum dots from the bottom-up, via self-assembly, says lead author Dhaneesh Kumar, a PhD student in the FLEET Centre of Excellence.

“We would be able to achieve densities tens of times larger than state-of-the-art, top-down synthesised inorganic systems.”

Scanning tunneling microscope
Scanning tunneling microscope images of DCA on Ag(111).

Quantum dots are extremely small – about one nanometre across (ie, a millionth of a millimetre).

Because their size is similar to the wavelength of electrons, their electronic properties are radically different to conventional materials.

Ordered arrays of charge-controllable quantum dots can find application in computing memory as well as light-emitting devices (eg, low-energy TV or smartphone screens).

Electric field control of molecular charge state in a single-component 2D organic nanoarray was published in ACS Nano. (DOI: 10.1021/acsnano.9b05950 )

For further information about this work contact Dr Agustin Schiffrin (experiment), from the School of Physics and Astronomy at Agustin.Schiffrin@monash.edu.


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