• • The Pt(II) emitter achieves an extremely narrow emission with FWHM of 16.0 nm and a Huang-Rhys factor of 0.278, indicating minimal structural relaxation and high color purity, which is critical for meeting BT.2020 display standards.
• • The emitter exhibits a high photoluminescence quantum efficiency of 95%, enabling efficient exciton harvesting and contributing to the high external quantum efficiencies (EQEs) of 32.6%, 29.4%, and 26.9% at 123, 1000, and 5000 cd/m2, respectively.
• • The deep-blue OLED achieves a record-high maximum brightness of 84,895 cd/m2 with CIE y < 0.15, overcoming the inherent insensitivity of the human eye to deep-blue light and enabling outdoor display applications.
• • The device maintains high EQE even at high luminance (26.9% at 5000 cd/m2), indicating low efficiency roll-off, which is essential for practical high-brightness applications.