Effects of source and substrate temperatures on the properties of ITO/CuPc/C60 heterostructure prepared by physical vapor deposition

Small-molecule organic photovoltaic (OPV) cells with a heterostructure of indium tin oxide (ITO)/copper phthalocyanine (CuPc)/C60/Ag were fabricated by physical vapor deposition at different source temperatures Tsou and substrate temperatures Tsub. The physical properties of these as-deposited organic thin films including surface morphology, structural information, and electrical and optical properties were measured (in layer-by-layer sequence) by atomic force microscopy, X-ray diffraction, current–voltage characteristics, and electronic absorption spectra. At first, the effects of different deposition conditions (Tsou and Tsub) on growth rate and film thickness of these organic thin films were examined. Then, the interface properties of ITO/CuPc and CuPc/C60 were studied with respect to Tsub. Short-circuit current density Jsc and open-circuit voltage Voc for this ITO/CuPc/C60/Ag heterostructure under illumination were performed, and the spectral response of Jsc was analyzed. Finally, the Tsub-dependence of the physical properties of the as-deposited organic films and of the performance of the as-fabricated OPV cells were discussed.