The continuous efforts devoted to improving the performances in organic photovoltaics (OPV) have enhanced the photoconversion efficiencies over 18% so far. However, a critical vision of the state-of-the-art publications highlights that thehighest efficiencies are generally paired with an enhancement of the synthetic complexity of both the materials (donor and acceptor) and the fabrication procedure. That is the reason why the preparation of simpler and less expensive materials is that crucial. In this regard, after a first chapter reviewing the recent progress in OPV, a second chapter is focused on the synthesis of D-π-A molecules based on the N-methyl-N-phenylthiophen-2-amine (MPTA) electron-donor unit, which was not previously used in the field. A series of derivatives is synthesized by modulating the π-spacer and the electron-withdrawing group A and theimpact on their optical, electrochemical and photovoltaic properties is naturally investigated. A third chapter is related to the structural modification of a recently reported push-pull molecule, namely TPA-T-DCV-Ph. Its additional phenyl ring in the accepting moiety led to a higher exciton diffusion length and therefore photoconversion efficiency in comparison to the well-known TPA-T-DCV. Hence, two different structural modifications of this donor are reported. Eventually, a fourth chapter is related to the functionalization of a promising and unexplored rylene, namely the benzothioxanthene (BTXI) whose most attractive features are its low synthetic cost and outstanding optical and electrochemical properties. Thus, its reactivity is explored in a deeper level and the properties of the new derivatives are studied.