Organic Photovoltaic Devices Incorporating Nanostructures in the Photoactive Layer: Towards Clean Solar Energy Generation

In this article we report the nanostructures formation in the thin films of several organic semiconductors. The thin films have been deposited onto glass substrates by a solution processable of spin-coating technique. The nanostructures are obtained by applying a simple surface solvent treatment process either by soaking or solvent vapor treatment. The influence of solvent treatment on the surface morphological properties has been investigated via a surface profilometer, absorption spectroscopy, X-ray Diffraction Spectroscopy and Atomic Force Microscopy (AFM). It reveals that the spin-coated TsCuPc thin films have nanostructures as evident from the surface profile image, which then confirmed by AFM image. Besides, the polymer chains have been re-organized after solvent treatment and the crystallinity is increased. Such crystalline increment provides a better pathway for charge carrier transport. The photovoltaic performance has improved to some extent for the device containing nano-structured film. We infer this enhancement is due to a larger interface area for exciton dissociation to generate free charge carriers of electrons and holes within the nanostructured film.