Side chain engineering of mono-fluorinated acceptors for efficient non-halogenated solvent-processed organic solar cells

A new NFA, BTz-δ-C 4 C 12 , was synthesized. The introduction of longer alkyl chains into the pyrrole unit suppresses excessive aggregation while maintaining sufficient π–π stacking. Therefore, the BTz-δ-C 4 C 12 -based device achieve an PCE of 16.6%.