Narrowband Tetradentate Pt(II) Complexes‐Based Deep‐Blue OLEDs with Low Efficiency Roll‐Off

This study designed and synthesized two tetradentate Pt(II) complexes featured with aryl- modified N-heterocyclic carbene (NHC) ligands, PtTJ-Ph and PtTJ-bPh, which exhibited narrow emission spectra with full-width at half-maximum (FWHM) of 19.0 and 19.8 nm in dichloromethane, respectively. They also showed remarkably high photoluminescence quantum yields of 99% and 93%, along with short excited-state lifetimes of 2.72 µs and 2.34 µs in poly(methyl methacrylate (PMMA) films, respectively. Deep-blue OLED device using PtTJ-Ph as emitter exhibited narrowband emission spectrum peaking at 458 nm with a small FWHM value of 25 nm, resulting in a small Commission Internationale de l'Éclairage (CIE) y coordinate of 0.138. The device also achieved a maximum external quantum efficiency (EQE) of 22.7%, and maintained an EQE of 20.8% at 1000 cd/m² with a low efficiency roll-off of only 8.3%, demonstrating excellent electroluminescent properties for deep-blue OLED application.