Leveraging TIPS-assisted one-pot di-bromination for thiazole-flanked NDI and PDI conjugated n-type semiconductors

High-performance unipolar n-type semiconductors are essential for advancing organic electronics. This study explores the impact of fluorination on thiazole-flanked naphthalenediimide (NDI) and perylenediimide (PDI) copolymers with benzothiadiazole (BT) acceptors. A novel one-pot bromination strategy enabled efficient synthesis of these electron-deficient monomers, which were subsequently copolymerized with fluorinated and non-fluorinated BT units. Optical and electrochemical analyses revealed that fluorination systematically lowers the LUMO energy levels, enhancing charge injection and n-type behavior. Fluorine substitution also influences molecular packing, as evidenced by UV-Vis absorption shifts, cyclic voltammetry, and grazing-incidence wide-angle X-ray scattering (GIWAXS). While moderate fluorination improves electron mobility by promoting backbone planarity and π-π stacking, excessive substitution disrupts molecular ordering, reducing charge transport efficiency. The optimized fluorinated copolymers exhibit electron mobilities up to 1.3 × 10⁻³ cm² V⁻¹ s⁻¹, demonstrating the potential of fluorination in tuning electronic properties for next-generation hybrid organic semiconductors.