3-dimensional anisotropic thermal transport in microscale poly(3-hexylthiophene) thin films

Anisotropy in material structure leads to distinct anisotropy in mechanical and thermal properties for polymer materials. In this work, poly(3-hexylthiophene) (P3HT) thin films are fabricated using the spin coating technique for investigation of anisotropic thermal transport. Raman spectroscopy study of spincoated P3HT films confirms the partially aligned molecular structure. Based on the main orientation of molecular chains, 3-dimensional thermal characterization is performed to understand the anisotropic thermal transport. The thermal conductivity varies from 0.1 to 3.18 W/m K and presents strong orientation-dependent feature. The anisotropy factor for in-plane thermal conductivity spans in the range of 2e4, lower than the factor for perfectly aligned structure. For thermal diffusivity, strong anisotropy is also observed. Particularly, for the out-of-plane direction, the thermal diffusivity is found almost one order of magnitude lower than that in the in-plane direction. 2013 Elsevier Ltd. All rights reserved.