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Increasing the Carrier Mobility in P3HT by Doping for use in Schottky Barrier TFTs

Published online by Cambridge University Press:  15 March 2011

G. C. R. Lloyd ,
N. Sedghi ,
M. Raja ,
R. Di Lucrezia ,
S. Higgins  and
W. Eccleston
G. C. R. Lloyd
Affiliation:
Dept of Electrical Engineering and Electronics, The Univ of Liverpool, Liverpool, UK
N. Sedghi
Affiliation:
Dept of Electrical Engineering and Electronics, The Univ of Liverpool, Liverpool, UK
M. Raja
Affiliation:
Dept of Electrical Engineering and Electronics, The Univ of Liverpool, Liverpool, UK
R. Di Lucrezia
Affiliation:
Dept of Chemistry, The Univ of Liverpool, Liverpool, UK
S. Higgins
Affiliation:
Dept of Chemistry, The Univ of Liverpool, Liverpool, UK
W. Eccleston
Affiliation:
Dept of Electrical Engineering and Electronics, The Univ of Liverpool, Liverpool, UK
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Abstract

Measurements and theory are presented examining the relationship between mobility and doping in regioregular poly(3-hexylthiophene) (P3HT). Mobility is found to increase super-linearly with doping and is comparable to models reported for other conjugated polymers. Schottky measurements have been used to calculate the doping density and bulk mobility of regioregular P3HT. Aluminium Schottky contacts showed signs of native oxide disrupting current flow through the device. This effect was observed to degrade further with the introduction of dopant into the polymer. Titanium devices show a general shift of the Schottky characteristic to higher current levels with increased dopant. Field effect mobility of P3HT films was also calculated using thin-film transistor (TFT) structures. The field effect mobility values were observed to be more than two orders of magnitude higher than the bulk mobility value. The addition of dopant also increased gate leakage currents in TFT devices. The increased conductivity in doped polymer can increase off currents in the device; this is avoided by using Schottky contacts as the source and drain. Preliminary results on Schottky contact TFTs are also presented as well as a description of the operation of such a device.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 708: Symposium BB – Organic Optoelectronic Materials, Processing and Devices , 2001 , BB10.57
Copyright
Copyright © Materials Research Society 2002

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References

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