High‐Performance Narrowband Pure‐Green OLEDs with Gamut Approaching BT.2020 Standard: Deuteration Promotes Device Efficiency and Lifetime Simultaneously

In order to fulfill the demand for ultrahigh definition organic light-emitting diodes (OLEDs), pure-green emitters with Commission Internationale de l'Éclairage (CIE) y-coordinate over 0.71 are in urgent demand. Meanwhile, the high device efficiency, small efficiency roll-off, and operational lifetime also remain challenging issues. In this work, a series of narrowband pure-green fluorescent emitters based on a double-boron (B) doped polycyclic aromatic hydrocarbons (PAHs) framework fused with naphthalene units is reported. The newly designed emitters realize green emission with peaks of 512-521 nm and extremely narrow full-width at half-maxima (FWHMs) of 16-17 nm in toluene solution. Utilizing these emitters in a phosphor-sensitized fluorescence (PSF) system, the resulting OLEDs exhibit pure green emission with peaks in the range of 514-526 nm and very narrow FWHMs of 19-20 nm. Notably, the devices based on the partially deuterated emitter, DBN-NaPh-d, not only achieve a maximum external quantum efficiency (EQE_max) as high as 35.2%, small efficiency roll-off, along with a CIEy of 0.74 but also showcase impressive operational stability with a long lifetime (LT₅₀) of over 3000 h at an initial luminance of 1000 cd m^-2. This work represents one of the highest device efficiencies and superior device stability among fluorescence emitter-based OLEDs.