Thermal characterization of metal phthalocyanine layers using photothermal radiometry and scanning thermal microscopy methods

The metal phthalocyanines (MePc) were thermally investigated using photothermal radiometry (PTR) and scanning thermal microscopy (SThM). Copper phthalocyanine and lead phthalocyanine layers with different thicknesses were deposited on Si (111) wafer and on glass substrates by physical vapor deposition in a high vacuum. SThM measurements allowed the determination of local thermal conductivity (κ) of studied MePcs. This method did not require any preliminary sample preparation. The influence of the substrate thermal properties on SThM thermal signal was taken into account for estimating the true value of κ for the organic layer. For PTR investigations MePcs were coated with an opaque aluminum film. Photothermal measurements enabled determination of the in-depth κ. To complement thermal investigations of MePc layers, quantitative analysis of surface morphology properties was performed by an atomic force microscopy. The results of thermal investigations were explained on the base of different surface morphologies of examined organic layers.