Discovery of donor polymers has an added dimension of not only monomer type but also their sequence. The most frequently seen units such as 99 and 61 are benzo(1,2-b:4,5-b')dithiophene (BDT) derivatives (Fig. ). The BDT motif can cause planar structures, whereas the side chains play a role not only in solubility, but also in optical and electronic properties . The structures of the top 10 donor polymer units (ESI Fig. ) have five monomers (1050, 260, 687, 920, and 824) showing very similar structures with various substituents or vinylene bridges. Analysis of the sequence shows the most common arrangement shows has multiple consecutive monomers separated by one or two of the other monomer (e.g. small blocks). Although this type of arrangement has already been seen and has shown success , the overwhelming design strategy in the literature is alternating copolymers (i.e. ABABAB).