There are 143 unique donor polymers, and 261 unique acceptor molecules. As seen from the heatmap in Figure , there are four common donors (PTB7-Th, J71, P3HT, and PBDB-T) and three common acceptors (ITIC, ITIC-4F, and m-ITIC). This is consistent with the field's general approach to materials design: scientists either design a donor or acceptor, and then that material is tested with a well-understood and easily available benchmark material. However, this results in sparsity and imbalance within the literature. Additionally, most combinations of materials are unexplored, and the D:A combinations that are present in the dataset mostly occur once or twice. Only for pairs of the most common materials (e.g., PTB7-Th and ITIC) are there a significant number of duplicate reports. Donor material energy levels (HOMO, LUMO) and energies (Eg opt , Eg HL ) do not fit cleanly within a distribution (Figure ) primarily due to the low number of unique molecular structures (143), while the same features for acceptors form smoother distributions due to the larger number of unique molecular structures (261). In both cases, over-represented materials are clearly visible by the large counts in material property values. Additionally, it should be noted that measuring energy levels of materials is often imprecise, and that there are known issues with the most common technique, cyclic voltammetry (CV). Polymer properties are much less frequently reported. We were only able to find 202 values of Đ (36% of the dataset), 185 for Mn (33%), and 106 for Mw (19%). Few papers even mention polymer molecular weight or dispersity, and many that do simply refer to a previous paper where the value was initially reported. The molecular weights and dispersities of commercial materials are barely reported.