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Abstract High‐efficiency and long‐lifetime near‐infrared (NIR) organic light‐emitting diodes (OLEDs) are rarely reported. Herein, three efficient NIR Ir(III) complexes 1 – 3 are developed with specially designed cyclometallated ligands based on pyrido3,4‐bpyrazine and oriented substitutions along the Ir─N bond axis. Electron‐deficient pyrazine ring effectively stabilizes LUMO energy, leading to significant emission bathochromic shift. Importantly, for complexes 2 and 3 , oriented substitutions along the direction of the Ir─N bond axis considerably enhance the horizontal emitting dipole orientation ratio up to 90%. Their OLEDs demonstrate high maximum external quantum efficiencies (EQEs), negligible efficiency roll‐offs, superior radiance, and long lifetimes. The maximum EQEs and radiances of devices are 9.84% and 158 W Sr −1 m −2 at 725 nm for 1 , 6.98% and 14.03 W Sr −1 m −2 at 760 nm for 2 , and 12.49% and 18.94 W Sr −1 m −2 at 735 nm for 3 , respectively. The device lifetime LT 97 at 10 mA cm −2 is 453 h for complex 2 , which sets a champion lifetime for NIR‐OLEDs. This work demonstrates that pyrido3,4‐bpyrazine is a desired building block for robust NIR emitting Ir(III) complexes, providing a superior paradigm to combine high efficiency, negligible roll‐off, and long device lifetime simultaneously toward practical applications.
Zhang et al. (Tue,) studied this question.