We have measured the interlayer and in-plane (needle axis) thermal diffusivity of 6,13-bis(triisopropylsilylethynyl) pentacene. The needle axis value is comparable to the phonon thermal diffusivities of quasi-one dimensional organic metals with excellent π-orbital overlap, and its value suggests that a significant fraction of heat is carried by optical phonons. Furthermore, the interlayer (c-axis) thermal diffusivity is at least an order of magnitude larger, and this unusual anisotropy implies very strong dispersion of optical modes in the interlayer direction, presumably due to interactions between the silyl-containing side groups. Similar values for both in-plane and interlayer diffusivities have been observed for several other functionalized pentacene semiconductors with related structures.

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Published in Applied Physics Letters, v. 105, no. 7, article 073302, p. 1-4.

Copyright 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

The following article appeared in Applied Physics Letters, v. 105, no. 7, article 073302, p. 1-3 and may be found at http://dx.doi.org/10.1063/1.4894094.

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This research was supported in part by the National Science Foundation, Grant No. DMR-1262261. The synthesis and crystal engineering of organic semiconductors were supported by the Office of Naval Research, Grant No. N00014-11-1-0328.

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