Ultrastable green top-emitting OLEDs approaching BT.2020 enabled by narrowband phosphorescent emitters

Highly stable and efficient organic light-emitting diodes (OLEDs) with high color purity are critical for ultrahigh-definition display applications. However, achieving these characteristics is hindered by the emitter bandwidth and device stability. Herein, we present the design of tetradentate green Pt(II) emitters with a rigid three-dimensional structure via extended π-conjugation and bulky substituents. This molecular engineering approach effectively suppresses excited-state geometric distortion, resulting in a small full width at half-maximum (FWHM) of 16.4 nanometers in toluene. When the emitters were used in a microcavity-enhanced top-emitting device, the FWHM was further reduced to 14.8 nanometers by controlling constructive and destructive interferences. The top-emitting device showed a Broadcast Service Television 2020 (BT.2020) green color [Commission Internationale de l'Éclairage (CIE): 0.22, 0.75] and a high current efficiency of up to 174 candelas per ampere. Most notably, the device exhibited a record-breaking operational stability, exceeding that of the commercial LED/OLED/MicroLED (micro-light-emitting diode) standard, achieving an unprecedented lifetime to 90% of the initial luminance of 540,100 hours at 1000 candelas per square meter.