AbstractOrganic solar cells (OSCs) have recently reached a remarkably high efficiency and become a promising technology for commercial application. However, OSCs with top efficiency are mostly processed by halogenated solvents and with additives that are not environmentally friendly, which hinders large‐scale manufacture. In this study, high‐performance tandem OSCs, based on polymer donors and two small‐molecule acceptors with different bandgaps, are fabricated by solution processing with non‐halogenated solvents without additive. Importantly, the two active layers developed from non‐halogenated solvents show better phase segregation and charge transport properties, leading to superior performance than halogenated ones. As a result, a tandem OSC with high efficiency of up to 16.67% is obtained, showing unique advantages in future massive production.