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Proceedings Paper

Charge transport properties of carbazole dendrimers in organic field-effect transistors
Author(s): Karyn Mutkins; Simon S. Y. Chen; Muhsen Aljada; Ben J. Powell; Seth Olsen; Paul L. Burn; Paul Meredith
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Paper Abstract

We report three generations of p-type dendrimer semiconductors comprised of spirobifluorene cores, carbazole branching units and fluorene surface groups for use in organic field-effect transistors (OFETs). The group of dendrimers are defined by their generation and noted as SBF-(Gx)2, where x is the generation. Top contact-bottom gate OFETs were fabricated by spin-coating the dendrimers onto an n-octyltrichlorosilane (OTS) passivated silicon dioxide surface. The dendrimer films were found to be amorphous. The highest mobility was measured for the first generation dendrimer (SBF-(G1)2), which had an average mobility of (6.6 ± 0.2) × 10-5 cm2/V s and an ON/OFF ratio of 3.0 × 104. As the generation of the dendrimer was increased there was only a slight decrease in the measured mobility in spite of the significantly different molecular sizes of the dendrimers. The mobility of SBF-(G3)2, which had a hydrodynamic radius almost twice of SBF-(G1)2, still had an average mobility of (4.7 ± 0.6) × 10-5 cm2/V s and an ON/OFF ratio of 2.7 × 103. Density functional theory calculations showed that the highest occupied molecular orbital was distributed over the core and carbazole units meaning that both intra- and intermolecular charge transfer could occur enabling the hole mobility to remain essentially constant even though the dendrimers would pack differently in the solid-state.

Paper Details

Date Published: 8 September 2011
PDF: 8 pages
Proc. SPIE 8117, Organic Field-Effect Transistors X, 811704 (8 September 2011); doi: 10.1117/12.892640
Show Author Affiliations
Karyn Mutkins, The Univ. of Queensland (Australia)
Simon S. Y. Chen, The Univ. of Queensland (Australia)
Muhsen Aljada, The Univ. of Queensland (Australia)
Ben J. Powell, The Univ. of Queensland (Australia)
Seth Olsen, The Univ. of Queensland (Australia)
Paul L. Burn, The Univ. of Queensland (Australia)
Paul Meredith, The Univ. of Queensland (Australia)


Published in SPIE Proceedings Vol. 8117:
Organic Field-Effect Transistors X
Zhenan Bao; Iain McCulloch, Editor(s)

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