A streamlined steric-shielding approach toward efficient narrowband (FWHM ∼ 18 nm) ultra-violet emitters for OLEDs

Herein, a simple, yet versatile molecular design was unraveled to develop a narrowband ultraviolet (UV) emitter by strategically integrating indolo[3,2,1-jk]carbazole and carbazole through a non-conjugative mode. The compound exhibited pure UV emission (λ_em ∼ 380 nm) with a narrow FWHM of 18 nm. When utilized as an emitter in OLEDs, it exhibited a maximum EQE of 3.5% and CIEy of 0.037. As a host for a green phosphorescent OLED, it demonstrated an EQE of 22.9% with an impressively low roll-off of 4% at 3000 cd m^-2.