Tuning the Electroluminescence of Binuclear Copper(I) Emitters Into the NIR-I Region

Optoelectronic devices that emit into the near infrared (NIR) region are appealing technologies with applications in optical communication and as disposable, lightweight and cheaper photodynamic biomedical devices. The development of efficient devices is currently hampered by the lack of suitable NIR-emissive materials. Achieving this goal is even more challenging when the use of non-toxic, earth-abundant metal complexes as electroactive materials is targeted. Herein, an enlarge family of binuclear Cu(I) emitters (D1–D4) bearing the bridging thiazolo[5,4-d]thiazole scaffold is described along with their mononuclear counterparts (M3–M4), which are synthetized and characterized comprehensively by a combination of chemical, spectroscopical, electrochemical and computational techniques. By means of an efficient dinuclearisation strategy in combination with the selective tuning of the π-accepting feature of the lateral N-heterocyclic rings enabled modulation of photo- and electro-luminescence spectra into the NIR-I region. Light-emitting electrochemical cells (LECs) fabricated by employing the binuclear copper complexes displayed electroluminescence into the deep-red to NIR-I region. Remarkably, derivative D2 shows the combination of λEL,max up to 782 with a spectral profile squarely falling into the NIR region, excellent carrier balance and good EL performances among all types of emissive materials used for NIR LECs.