A NIR dye with high-performance n-type semiconducting properties

A novel hetero-polycyclic aromatic compound manifesting strong near-infrared (NIR) absorption as well as high-performance n-type semiconducting properties is developed. With an exceptionally low LUMO level at –4.7 eV, this NIR dye (λ(max) ≈ 1100 nm, ε ≈ 10(5) mol(–1) L cm(–1)) exhibits adequate stability under ambient conditions, with electron mobility up to 0.96 cm(2) V(–1) s(–1) measured in solution-processed organic field-effect transistors. A special metal-free C–C coupling serves as a pivotal step in constructing the polycyclic π-framework of this low-bandgap chromophore, by fusing an electron-deficient naphthalenediimide moiety with an electron-donating naphthalenediamine. Such a rare combination of extraordinary optical and semiconductive attributes is quite valuable for organic small molecules, and promising for unique applications in the opto-electronic field.