As one of the most promising solar cell technologies, organic solar cells have unique superiorities distinct from inorganic counterparts, such as semitransparency, flexibility and solution-processability, as well as tunable photophysical properties, which originate from the structural verstailities of organic semiconductors. A major breakthrough in OSCs was the exploration of novel non-fullerene electron acceptor (NFAs): In comparison with traditional fullerene derivative acceptors, NFA possesses several advantages, such as low synthesis cost, tunable absorption range and adjustable...