Improved charge conduction in cobalt-phthalocyanine thin films grown along 36.8° boundary of SrTiO3 bicrystals

We have investigated temperature dependence of resistivity (rho) and current-voltage characteristics of cobalt-phthalocyanine (CoPc) films deposited (i) along the 36.8 degrees boundary (ATB) and (ii) in the single crystal region (SCR) of SrTiO3 bicrystal substrates. The analyses of rho-T data show that while ATB films exhibit critical behavior, SCR films follow insulating three-dimensional variable-range-hopping mechanism. The mobility (mu) at 300 K has been estimated to be similar to 148 and 3.8 x 10(-3) cm(2) V-1 s(-1), respectively for ATB and SCR films. A very high mu for ATB films indicates that the bicrystal boundary acts as a template for the ordering of CoPc molecules. (C) 2011 American Institute of Physics. [doi:10.1063/1.3574776]