Substituent-Controlled Design of Naphthalene Diimide-Based Materials Exhibiting Semiconducting Behavior.

This work introduces five core 2,6-diaryl-substituted naphthalene diimide (NDI) derivatives accessed through Suzuki-Miyaura cross-coupling, employing imide-functionalized NDIs bearing 2-ethylhexyl side chains. The strategic incorporation of electron-donating and electron-withdrawing aryl groups at the 2,6-positions of the electron-deficient NDI core enabled systematic tuning of the electronic and optical properties of NDI derivatives. UV-Vis absorption studies showed the development of Q-bands and bathochromic shifts, depending on the electronic properties of the substituents, which are essential for optimizing optoelectronic functionality. The experimental observations were further supported by density functional theory calculations, offering deeper insight into the extent of electronic delocalization and the spatial distribution of the frontier molecular orbitals. The semiconducting behavior of all five compounds has been evaluated by fabricating them into Schottky diode devices. With different charge transport properties connected to the electronic characteristics of the core substituents, the resultant devices showed distinct structure-property correlations. Core-engineered NDIs are proven to be adaptable soft materials for tunable organic electronic applications in this study.