<p>The development of high-performance n-type organic semiconductor materials is crucial for advancing organic field-effect transistors (OFETs) and their integration into p-n complementary logic circuits. A deep understanding of the structure-property relationships in these materials is essential for their optimization. In this study, we focus on designing and synthesizing two novel n-type triple-acceptor triads, NTI-BTT and NTI-BT, utilizing monothiophene-extended naphthalene diimide (NDI), specifically naphtho[2,3-<i>b</i>]thiophene diimide (NTI). Our investigation centers on how thiophene extensions, achieved through either fusion and/or spacer insertion, influence the physicochemical and charge transport properties of these materials. Notably, the NTI-terminated triads exhibit enhanced electron-withdrawing capabilities compared to their NDI-based counterpart. This enhancement is characterized by deeper energy levels and more planar backbones. However, a significant discrepancy is observed in NTI-BT-based OFETs, where thiophene fusion leads to a substantial drop in electron mobility to 0.004 cm² V⁻¹ s⁻¹. This discrepancy arises from the polycrystalline structure, where multiple grain boundaries between crystallites increase the density of trap states, resulting in lower mobility. Encouragingly, the introduction of thiophene spacers between the NTI and benzothiadiazole units in NTI-BTT is found to effectively enhance n-type charge transport. This molecular modification improves π-π interactions and reduces intermolecular distances, resulting in a short π-π stacking distance of 3.45 Å. Consequently, NTI-BTT exhibits a significantly improved electron mobility of 0.13 cm² V⁻¹ s⁻¹, which is four times higher than that of the NDI-based counterpart. These findings contribute significantly to the search for high-performance n-type materials and offer valuable insights into the design principles for advanced OFETs.</p>