Multi-component organic films have increasing applications in photovoltaic technologies and other electronic devices. These applications depend strongly on the structural and electronic properties of the heterojunctions. In this talk I will present a detailed investigation of these important aspects, such as structure control and structural-electronic correlation in semiconductor molecular films, for selected “donor-acceptor” model systems (TiOPc-C60 and TiOPc-C70) using STM/STS. I will show how to use growth kinetics selectively prepare desired one-component film and then employ it as template for further growth of the molecular heterojunctions.