π-Electron reorganization in polycyclic aromatic hydrocarbons toward BT.2020-compliant narrowband red emitters

Narrowband red emission remains a long-sought target for organic light-emitting diodes (OLEDs) but has proven exceptionally difficult to realize using polycyclic aromatic hydrocarbons (PAHs). Herein, we introduce a general molecular design paradigm that harnesses π-electron reorganization through skeletal reconstruction in PAHs. This topological engineering localizes aromaticity into discrete segments, intrinsically suppressing vibronic coupling and yielding exceptionally narrowband emission. Using ovalene as a model system, we created a family of PAH-based fluorophores spanning yellow to deep red (559-670 nm) with exceptionally narrow full-width at half-maximum (FWHM) values of 18-24 nm. When integrated into sensitized OLEDs, these emitters deliver record-setting device performance. A representative compound produces sharp red emission at 639 nm with a FWHM of only 28 nm/0.085 eV, Commission Internationale de l'Éclairage (CIE) coordinates of [0.704, 0.294] that precisely match the BT.2020 red standard ([0.708, 0.292]), and an external quantum efficiency exceeding 24%-the highest reported value for traditional red fluorescent systems. To our knowledge, this constitutes the first demonstration of a BT.2020-compliant red emitter with FWHM below 30 nm.