Enhancing efficiency and brightness of deep-blue phosphorescent OLED enabled by a narrowband Pt(II) emitter
Organic light-emitting diodes (OLEDs) are an advanced technology for full-color displays, yet the low efficiency of blue OLEDs remains a critical bottleneck. Here, we report a new strategy to design robust Pt(II) emitters with enhanced molecular rigidity and increased locally excited character. The resulting Pt(II) emitter exhibits an extremely narrow emission spectrum peaking at 458.6 nm with a full-width at half-maximum (FWHM) of 16.0 nm and a small Huang-Rhys factor of 0.278, together with a high photoluminescence quantum efficiency of 95%. When doped into an OLED, the device emits at 464 nm with high color purity (FWHM = 19 nm) and achieves high external quantum efficiencies (EQEs) of 32.6%, 29.4%, and 26.9% at luminances of 123, 1000, and 5000 cd/m2, respectively. Notably, the device attains a record-high maximum brightness of 84,895 cd/m2 among reported deep-blue OLEDs with Commission Internationale de l'Éclairage (CIE) y-coordinate < 0.15. This work demonstrates one of the highest-performing deep-blue OLEDs reported to date, addressing the dual challenges of efficiency and brightness in this spectral region.