Heating it up: a novel approach to annealing soluble organic semiconductors

The aim of this projhect is to study the electronic properties of organic (carbon-based) semiconductor materials and to study electronic devices, such as FETs, made using these materials. Organic semiconductors offer a number of advantages including ease and low-cost of device fabrication and chemical versatility. While irganic display technologies and light emitting devices are currently on the market, organic transistors are still and active area of scientific research, particularly for applications requiring higher electrical mobility to enable faster switching. My research was focused on triethylsilylethynyl-anthradithiophene (TES-ADT), a small molecule organic semiconductor. TES-ADT can be dissolved in toluene and spin-cated onto pre-fabricated FET structures on a degenerately-doped silicon substrate, which is used as the gate. A 400nm thick thermally grown oxide is used to insulate the semiconductor gate from the Ti/Au source and drain leads. The as-deposited TES-ADT film is amorphous, and recent work by the Anthony group at the University of Kentucky has shown that this film can be crystallised by exposure toa solvent vapour, typically dichloroethane, leading to substantially imporved electrical characteristics of the TES-ADT FET and mobilities up to 1.5 * 10^-1 cm^2/Vs. In this thesis, I report research on an alternative route to crystallising TES-ADT films, namely a thermal anneal process. It involves heating the film to a temperature between 70 to 130 degrees (C), but less than the melting point of 154 degrees (C), obviating the need for the solvent anneal process. FET characteristics are obtained, with mobilities up to 4.72 * 10^-3 cm^2/Vs that are comparable to those obtained via the solvent anneal process and those obtained with other organic materials. This thesis contains substantial details relating to optimisation of the thermal anneal process, focussing heavily on polarized optical microscopy as a characterisation method. There was also some study into photo-enhanced conductivity with the TES-ADT.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2010

Author dc:creator

• Muhieddine, Khalid

• Soluble
• Organic Semiconductor
• Thermal Anneal
• TES-ADT

Statement dc:rights

• open access
• CC BY-NC-ND 3.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by-nc-nd/3.0/au/

Language dc:language

EN

Identifier

https://doi.org/10.26190/unsworks/23434

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/50254