Recent studies have emphasized that solution-state aggregation of polymers is central to achieving favorable blend film morphology of OSCs, thereby potentially helping to overcome the aforementioned morphology control challenges. For instance, a prominent work done by Qian and Hou et al. has shown that using a strongly aggregated solution of PBDTBDD for fabrication of OSCs yielded a superior device performance owing to the formation of nanoscale phase-separated domains whereas using a thermally treated solution with reduced aggregation led to larger domains which limited charge generation and deteriorated the device performance. From the processing aspect, Hernandez and Reynolds et al. has achieved the same film morphology and device performance for both spin coated and blade coated OSCs which was attributed to using an aggregated polymer solution that predetermines the morphology. However, studies have also demonstrated that excessive aggregation of polymers in solution causes difficulty in processing and leads to large crystalline domains which are detrimental to charge generation. Recently, using polymers that exhibit temperature-dependent aggregation in solution partially resolved this issue as the strong solution-state aggregation of these polymers can be reduced by simply increasing the solution temperature before film deposition. For instance, Liu and Yan et al. was able to process aggregated solutions by heating up the solution before spin coating; however, the resulting film morphology, specifically the crystallinity, exhibited large dependence on the spin coating rate. Similarly, many approaches have been reported to tune the solution-state aggregation of polymers for morphology control including but not limited to, varying the concentration of the polymer solution, molecular weight, side-chain modification, thermal history of the solution, solvent additives, solution aging-time, solution temperature, and processing temperature. Unfortunately, it remains unclear what type of aggregates are beneficial for achieving favorable BHJ morphology with high processing resiliency. Therefore, the purpose of this study is to provide a complete structural insight into polymer solution-state aggregation and understand how it translates to the BHJ morphology and processing resiliency of non-fullerene based organic solar cells.