Molecular Engineering of a Rigid Tetradentate Pt(II) Emitter for High-Performance OLEDs Realizing the BT.2020 Blue...

Organic light-emitting diodes (OLEDs) hold great promise for next-generation ultra-high-resolution 4 K/8 K display technologies. However, the development of high-efficiency deep-blue OLEDs based on tetradentate Pt(II) emitters that simultaneously meet the BT.2020 blue color gamut and low efficiency roll-off remains a formidable challenge. In this study, we designed a rigid, narrow-spectrum, deep-blue phosphorescent Pt(II) emitter, PtCK1, by strategic regulation of excited-state properties and incorporation of bulky three-dimensional steric geometry. PtCK1 exhibits excellent photophysical properties, including a small full width at half maximum (FWHM) of 15.6 nm and a high photoluminescence quantum yield of 97%. As a result, PtCK1-bottom-emitting OLED achieves deep-blue emission with a peak at 460 nm, an FWHM of 21 nm, and a maximum external quantum efficiency of 25.3%. Even at luminance levels of 5000 cd m^-2, the EQEs remain as high as 19.3%. Impressively, top-emitting phosphorescent OLED achieves improved color purity, with an ultranarrow spectrum (FWHM = 14 nm), Commission Internationale de l'Éclairage (CIE) coordinates of (0.139, 0.046), fully satisfying the BT.2020 blue standard, and especially a record-high maximum blue index (BI) of 397 cd A^-1 CIE_y ^-1 with CIE_y < 0.05. This study provides a valuable strategy for developing high-performance tetradentate Pt(II) emitters that meet the BT.2020 blue gamut.