Thermal transport properties of thin films of small molecule organic semiconductors

A series of harmonic Joule-heating experiments have been employed to determine the thermal conductivities of thin films of pentacene, N, N'-diphenyl-N, N'-di(3-methylphenyl)-(1,1'-biphenyl )-4,4'-diamine, and tris(8-hydroquinolinato)aluminum, three widely used organic semiconductors. Room-temperature thermal conductivity values of 0.51, 0.24, and 0.48 W/mK were measured for films of these three compounds, respectively. These values are over two orders of magnitude lower than those of inorganic semiconductors. While amorphous films were found to display only small thermal conductivity changes over the temperature range of 228-350 K, pentacene exhibited stronger variations that are typical of phonon-phonon scattering observed in polycrystalline semiconductors. (c) 2005 American Institute of Physics.