Effects of substrate temperature on copper(II) phthalocyanine thin films

We report the crystal and band gap structures of copper(II) phthalocyanine (Cu–Pc) thin films depending on the substrate heating conditions and temperatures. The phase changes of the two α- and β-phases of Cu–Pc thin films due to different heating conditions were observed by using X-ray diffractions and electronic absorption spectra. As the temperatures increased from room temperature to 300 °C, the energy gap was changed from 1.8052 to 1.7844 eV and the crystal structure of Cu–Pc thin films was transformed from orthorhombic α-phase to monoclinic β-phase. The orientation of grains depended on the heat-treatment conditions and the temperatures of the substrate during film deposition. The transport properties of Cu–Pc thin films with different grain orientations were studied.