Iridium(III) Complexes Based on Indolo[3,2,1‐jk]carbazole Derivatives for Narrowband Organic Light‐Emitting Diodes with External Quantum Efficiency of 32.3% and Low Efficiency Roll‐Off

Abstract

Iridium(III) complexes have been widely used in organic light‐emitting diodes (OLEDs) due to their high efficiency and stability. However, the wide emission bands of most Ir(III) complexes affect the color purity and the device performance. Herein, three narrowband Ir(III) complexes (Ir1–Ir3) based on indolo[3,2,1‐jk]carbazole moiety with pyridine group bound to the 9‐position are synthesized. The trimethylsilyl and trifluoromethyl substituents tune the emission color from yellow (567 nm) to orange (577 nm) and red (620 nm) with small full width at half maximum (FWHM) of 38, 40, and 49 nm (1120, 1186, and 1262 cm−1) in toluene solutions, respectively. Furthermore, these complexes exhibit high photoluminescence quantum yields of up to 88% and short phosphorescent lifetimes of down to 0.59 μs in doped films. Employing three complexes as emitters, the electroluminescence spectra of devices also show narrow FWHMs of 43, 45, and 53 nm (1294, 1310, and 1379 cm−1), respectively. Furthermore, all devices show high efficiencies, accompanied by low efficiency roll‐offs. The results provide a reliable strategy for designing highly efficient Ir(III) complexes with narrowband emissions for OLEDs.