Ambipolar Carrier Mobility in Binary Blend Thin Film of Non-Peripheral Alkylphthalocyanines

Charge carrier mobility in blend films of two types of soluble phthalocyanine derivatives with different substituent length, 1,4,8,11,15,18,22,25-octapentyl-phthalocyanine (C5PcH(2)) and 1,4,8,11,15,18,22,25-octahexyl-phthalocyanine (C6PcH(2)) has been investigated. The charge carrier mobility was measured by the time-of-flight technique. In the case of C5PcH2 blend ratio below 25 mol%, the high mobility, such as 0.8-1.1 cm(2)V(-1)s(-1) for hole and 0.6 cm(2)V(-1)s(-1) for electron, were obtained at room temperature. In the thin films with C5PcH(2) above 30 mol%, the charge carrier mobility decreased by one order of magnitude and had the different temperature dependence from that below 25 mol%. The marked change of the charge carrier mobility depending on the blend ratio of phthalocyanine derivatives has been discussed by taking the miscibility and the molecular packing structure into consideration.