In this presentation we will report the molecular design, synthesis, and molecular and structural characterization of new molecular building blocks, donor polymers and non-fullerene acceptors for organic photovoltaic cells. New donor polymers were designed on easily accessible building blocks and avoid fluorination to facilitate synthetic strategies but delivering PCEs > 10% (in modules) and >17% (on small cells). Furthermore, we demonstrate new molecular and polymeric NFAs where combination of atomic substituent and regiochemical substituent arrangement (for the molecular) as well as co-monomer unit (for the polymeric) enable good structural order, good electron mobilities, and achieve optimal paring with several donor polymers. Finally, we summarize recent strategies to organic and oxide interlayers for realizing highly efficient and stable perovskite cells.