Organic solar cells form a class of thin-film photovoltaics offering attractive prospects for renewable energy production by providing low-cost, flexible and aesthetically appealing devices printable on large surfaces. In bulk heterojunction organic photovoltaics, electron donor and acceptor molecules are intimately mixed in the photoactive layer. The lab efficiency of said devices has steadily increased due to growing insights in the underlying physical phenomena, device optimization and chemical engineering of a myriad of donor materials. Till recently, fullerenes turned out to be the superior electron acceptors, but this has now changed and different classes of non-fullerene acceptors have emerged, pushing the efficiencies of organic solar cells beyond the conventional boundaries. In this project, we investigate the crucial factors affording high performance in fullerene-free organic solar cells and design novel blends comprising of advanced donors and acceptors. By optimizing photon harvesting, blend morphology and charge separation/transport, while reducing recombination losses, the project aims at increased device efficiencies and a substantial fundamental contribution to this exciting emerging research field.