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Hall Effect of Solution-crystallized and Vapor-deposited 2,7-Dioctylbenzothieno[3,2-b]Benzothiophene Field-effect Transistors

Published online by Cambridge University Press:  01 February 2011

Masakazu Yamagishi
Affiliation:
yamamasa@chem.sci.osaka-u.ac.jp, Osaka University, Graduate School of Science, Toyonaka, Japan
Takafumi Uemura
Affiliation:
uemura-t@sanken.osaka-u.ac.jp, Osaka University, Department of Chemistry, Graduate School of Science, Toyonaka, Japan
Yuichi Takatsuki
Affiliation:
takatuki@chem.sci.osaka-u.ac.jp, Osaka University, Graduate School of Science, Toyonaka, Osaka, Japan
Junshi Soeda
Affiliation:
soeda@chem.sci.osaka-u.ac.jp, Osaka University, Graduate School of Science, Toyonaka, Osaka, Japan
Yugo Okada
Affiliation:
yugo@chem.sci.osaka-u.ac.jp, Osaka University, Graduate School of Science, Toyonaka, Osaka, Japan
Yuri Hirose
Affiliation:
yhirose@chem.sci.osaka-u.ac.jp, Osaka University, Graduate School of Science, Toyonaka, Osaka, Japan
Yasuhiro Nakazawa
Affiliation:
nakazawa@chem.sci.osaka-u.ac.jp, Osaka University, Graduate School of Science, Toyonaka, Osaka, Japan
Shoji Shinamura
Affiliation:
m084755@hiroshima-u.ac.jp, Hiroshima University, Graduate School of Applied Chemistry, Higashi-hiroshima, Japan
K. Takimiya
Affiliation:
ktakimi@hiroshima-u.ac.jp, Hiroshima University, Graduate School of Applied Chemistry, Higashi-hiroshima, Japan
Jun Takeya
Affiliation:
takeya@sanken.osaka-u.ac.jp, Osaka University, Graduate School of Science, Toyonaka, Osaka, Japan
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Abstract

Gate-voltage dependent Hall coefficient RH is measured in high-mobility field-effect transistors of solution-crystallized and vapor-deposited 2,7-dioctylbenzothieno[3,2-b]benzothiophene. The value of RH evolves with density of accumulated charge Q, precisely satisfying the free-electron formula RH = 1/Q near room temperature. The result indicates that the intrinsic charge transport inside the grains is band-like in the high-mobility organic-semiconductor thin films that are of significant interest in industry. At lower temperature, even Hall-effect mobility averaged over the whole polycrystalline film decreases due to the presence of carrier-trapping levels at the grain boundaries, while the free-electron-like transport is preserved in the grains. With the separated description of the inter- and intra-grain charge transport, it is demonstrated that the reduction of mobility with decreasing temperature often shown in organic thin-film transistors does not necessarily mean mere hopping transport.

Type
Research Article
Copyright
Copyright © Materials Research Society 2010

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References

REFERENCES

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