This article presents a study on the development of high-efficiency polymer solar cells (PSCs) through the control of aggregation and morphology. The researchers achieved high-performance PSCs with efficiencies up to 10.8% and fill factors up to 77% using three different donor polymers and 10 polymer:fullerene combinations. The key to this success was the formation of a near-ideal polymer:fullerene morphology, characterized by highly crystalline yet reasonably small polymer domains. This morphology was controlled by the temperature-dependent aggregation behavior of the donor polymers and was insensitive to the choice of fullerenes. The study highlights the importance of polymer design and morphology control in achieving high-performance PSCs, and demonstrates that the use of different fullerenes can lead to improved performance. The research also shows that the aggregation and morphology control approach can be applied to multiple polymer:fullerene materials systems, enabling further synthetic advances and material matching. The findings suggest that this approach can significantly improve PSC performance and increase design flexibility. The study also discusses the importance of polymer crystallinity and hole mobility in achieving high-performance PSCs, and highlights the role of polymer:fullerene domain size and purity in determining device performance. The research provides insights into the structural features of donor polymers that enable optimal aggregation and morphology control, and demonstrates that the branching position and size of alkyl chains are critical in achieving this. The study also shows that the use of different processing conditions, such as temperature and spin rate, can significantly affect the morphology and performance of PSCs. Overall, the study demonstrates that controlling aggregation and morphology is crucial for achieving high-performance PSCs, and provides a framework for further research and development in this area.This article presents a study on the development of high-efficiency polymer solar cells (PSCs) through the control of aggregation and morphology. The researchers achieved high-performance PSCs with efficiencies up to 10.8% and fill factors up to 77% using three different donor polymers and 10 polymer:fullerene combinations. The key to this success was the formation of a near-ideal polymer:fullerene morphology, characterized by highly crystalline yet reasonably small polymer domains. This morphology was controlled by the temperature-dependent aggregation behavior of the donor polymers and was insensitive to the choice of fullerenes. The study highlights the importance of polymer design and morphology control in achieving high-performance PSCs, and demonstrates that the use of different fullerenes can lead to improved performance. The research also shows that the aggregation and morphology control approach can be applied to multiple polymer:fullerene materials systems, enabling further synthetic advances and material matching. The findings suggest that this approach can significantly improve PSC performance and increase design flexibility. The study also discusses the importance of polymer crystallinity and hole mobility in achieving high-performance PSCs, and highlights the role of polymer:fullerene domain size and purity in determining device performance. The research provides insights into the structural features of donor polymers that enable optimal aggregation and morphology control, and demonstrates that the branching position and size of alkyl chains are critical in achieving this. The study also shows that the use of different processing conditions, such as temperature and spin rate, can significantly affect the morphology and performance of PSCs. Overall, the study demonstrates that controlling aggregation and morphology is crucial for achieving high-performance PSCs, and provides a framework for further research and development in this area.