Microcrystalline silicon is a complex material that exhibits a wide range of possible microstructures depending on both the deposition conditions and substrate material. Many efforts have been laid in the past years in understanding the growth mechanisms of this material and the relationship between microstructure and solar cell efficiency. On the other hand, the amorphous nature and the metastable properties of hydrogenated amorphous silicon material also lead to different controversial issues remaining discussed, so that research remains active in this domain too. Finally, in order to achieve high efficiency with thin films of silicon, a high light confinement is fundamental and advanced cell designs integrating textured front-electrodes obtained via LPCVD deposition of ZnO or via the nano-imprinting fabrication of transparent nanostructures covered by highly transparent conductive oxides are developed, together with advanced solar cell designs allowing for high electrical properties on such rough substrates.