||Developing thin film technologies such as CIGS, CdTe, perovskite, and polymer solar cells (PSCs) is required to prepare for post-Si solar cell era. Among those alternatives, PSCs are particularly promising because they can fulfill the current needs of highly efficient and foldable electronics. To obtain high efficiency, tuning the active layer blend morphology, comprising donor, acceptor, and mixed amorphous regions is of paramount importance. Herein, we present effective strategies to manipulate the binary and ternary morphologies by calculating component interactions among polymer, fullerene, and solvent. We also quantify domain size and fullerene compositions by utilizing soft and hard X-ray based synchrotron techniques. By this approach, we could provide a linear correlation between FF and root-mean-square fullerene composition irrespective of the overall complexity of morphologies. This could serve as design criteria for efficient electronic devices.