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Effect of keto defects on the electrical properties of fluorene-based oligomers

Authors :
Yong-Young Noh
Reiko Azumi
Eunhee Lim
Hong-Ku Shim
Byung Jun Jung
Yuji Yoshida
Dong-Yu Kim
Kiyoshi Yase
Source :
Applied Physics Letters. 85:2953-2955
Publication Year :
2004
Publisher :
AIP Publishing, 2004.

Abstract

The effect of ketonic defects on electrical properties, i.e., the performance of organic field-effect transistors (OFETs) was examined in fluorene end capped fused bithiophene oligomers (BFTT). The long wavelength emission at 2.1–2.3eV resulting from the ketonic defects was observed in photoluminescence spectra of BFTT films after UV irradiation in air. In addition, the peak corresponding to the carbonyl stretching mode of the fluorenone moiety at 1721cm−1 was also apparent after UV irradiation for periods longer than 6h in air. These observations confirm that ketonic defects are present in the fluorene units of BFTT after photo-oxidation. The threshold voltage (Vth), i.e., switch-on voltage, of OFETs was increased and field-effect mobility (μFET) was decreased after the formation of the ketonic defects, since these defects induce the formation of numerous trap sites in the bandgap of the semiconducting conjugated oligomer.

Details

ISSN :
10773118 and 00036951
Volume :
85
Database :
OpenAIRE
Journal :
Applied Physics Letters
Accession number :
edsair.doi...........46b27878fc0776b1c907b79d78a4b820