Fluorination, one of the molecular engineering methodologies, has many advantages in modulating the electronic and structural properties of pi-conjugated small molecules and polymers for organic electronic devices. Despite significant changes in chemical and physical properties upon fluorination, there have been relatively few studies on organic semiconductors containing fluorinated thiophene derivatives due to their synthetic complexity. To address this issue, we developed the electrophilic fluorination method by solvent optimization, affording the site-selective (at the 3-position or 4-positon) and multiple fluorination (up to tetrafluorination) of thiophene-based heterocyclic derivatives. In addition, we demonstrate that the two fluorine substituents on the FTVT unit impart a dipole moment in the polymer back-bone, leading to a fast and robust aggregation process (mainly a kinetic process), which suppresses NDI-driven self-assembly process (a thermodynamic process).