Naphthalene diimide (NDI)-based polymers are widely used in organic electronic devices as a n-type material. Most NDI-based polymers have large crystal domains through NDI-driven self-assembling process, which limits an efficient electron transportation in amorphous region. Increasing interconnectivity by forming localized aggregates can provide effective approach to improve electron mobility in amorphous region and lower the activation energy in charge transportation. To realize this logic, we synthesized the copolymer of NDI and fluorinated dithienylethene (FTVT) unit (PNDI-FTVT). FTVT unit formed localized aggregates via kinetically fast and robust intermolecular interactions. These aggregates hinder self-assembling process driven by NDI unit as well as increase the interconnectivity between polymer chains in amorphous region, resulting in one order higher the bulk electron mobility compared to PNDI-TVT.