Effect of substrate temperature on the structure and morphology of copper phthalocyanine (CuPc) films for photovoltaic applications

Copper Phthalocyanine (CuPc) is a well-studied small molecular material for organic solar cells. It has been shown that forming crystalline nanowires of CuPc and aligning the molecules along an axis normal to the substrate will lead to better stacking, fewer grain boundaries, high crystallinity and mobility in solarcells. Annealing the substrate during vapor deposition of CuPc films produce vertical crystalline rods which may create an ideal heterojunction structure for solarcells. Here we demonstrate deposition with substrate heating of CuPc films on ITO/MoO₃ substrates at temperatures 100°C, 150°C and 200°C and comparison of morphology with unheated samples. Morphologies of films are characterized using optical microscope, SEM and AFM studies. Photo absorption of films is studied with UV-visible absorption spectroscopy. Attempts are also made to investigate the impact of such structures on photovoltaic applications. (author)