Luminescence Color Tuning from Blue to Near Infrared of Stable Luminescent Solid Materials Based on Bis-o-Carborane-Substituted Oligoacenes

Aryl-substituted o-carboranes have shown highly efficient solid-state emission in previous studies. To demonstrate color tuning of the solid-state emission in an aryl-o-carborane-based system, bis-o-carborane-substituted oligoacenes were synthesized and their properties were systematically investigated. Optical and electrochemical measurements revealed efficient decreases in energy band gaps and lowest unoccupied molecular orbital (LUMO) levels by adding a number of fused benzene rings for the extension of pi-conjugation. As a consequence, bright solid-state emission was observed in the region from blue to near infrared (NIR). Furthermore, various useful features were obtained from the modified o-carboranes as an optical material. The naphthalene derivatives exhibited aggregation-induced emission (AIE) and almost 100% quantum efficiency in the crystalline state. Furthermore, it was shown that the tetracene derivative with NIR-emissive properties had high durability toward photo-bleaching under UV irradiation.