Thermal Diffusivities of Functionalized Pentacene Semiconductors

TL;DR

This study measures the thermal diffusivities of functionalized pentacene semiconductors, revealing significant anisotropy and optical phonon contributions, which are crucial for understanding heat transport in organic semiconductors.

Contribution

It provides the first detailed measurements of interlayer and in-plane thermal diffusivities in functionalized pentacene semiconductors, highlighting anisotropic heat transport mechanisms.

Findings

In-plane diffusivity comparable to phonon conductivities in organic metals

Interlayer diffusivity is at least ten times larger than in-plane

Strong dispersion of optical modes due to side group interactions

Abstract

We have measured the interlayer and in-plane (needle axis) thermal diffusivities of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn). The needle axis value is comparable to the phonon thermal conductivities of quasi-one dimensional organic metals with excellent pi-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.