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Proceedings Paper

Band bending and Debye screening in F16CuPc/BP2T ambipolar organic thin film transistor
Author(s): H. Ding; Y. Gao; H. Wang; D. Yan
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Paper Abstract

There has been a considerable interest on forming ambipolar organic thin film transistors (OTFTs) because such devices are advantageous for integrated circuits, such as lower power consumption, design and fabrication simplification, and better immunity. Most recently, Shi et al. observed a substantial mobility improvement in ambipolar OTFTs based on the heterojunction formed between copper-hexadecafluoro-phthalocyanine (F16CuPc) and 2,5-bis(4-biphenylyl) bithiophene (BP2T). Specifically, the hole and electron mobility are improved by 3 and 12 folds from the bulk values, respectively. We examined the interface formation between F16CuPc and BP2T using ultraviolet photoemission (UPS) and inverse photoemission spectroscopy (IPES). It is observed that in F16CuPc/BP2T the heterojunction is characterized by band bending in both materials, while in BP2T/F16CuPc the band bending is confined in BP2T only. For F16CuPc/BP2T, the band bending of BP2T and F16CuPc are 0.40 and 0.35 eV, respectively. The band bending region is ~15 nm in both materials, from which the Debye lengths of the materials can be deduced. The combination of the band bending and finite Debye lengths offers an explanation to the observed improvement and thickness dependence of the mobility in OTFTs based on such heterojunctions.

Paper Details

Date Published: 27 August 2008
PDF: 9 pages
Proc. SPIE 7054, Organic Field-Effect Transistors VII and Organic Semiconductors in Sensors and Bioelectronics, 70540E (27 August 2008); doi: 10.1117/12.798962
Show Author Affiliations
H. Ding, Univ. of Rochester (United States)
Y. Gao, Univ. of Rochester (United States)
H. Wang, Institute of Applied Chemistry (China)
D. Yan, Institute of Applied Chemistry (China)

Published in SPIE Proceedings Vol. 7054:
Organic Field-Effect Transistors VII and Organic Semiconductors in Sensors and Bioelectronics
Zhenan Bao; Ruth Shinar; Iain McCulloch, Editor(s)

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