Hybridizing Carbonyl-/Nitrogen- and Carbon-/Nitrogen- Multiple Resonant Motifs for Efficient Pure Green TADF Emitters

In next-generation displays, green emission carries weight for widening the color gamut comparing to blue and red emissions. Multi-resonant (MR) emitters hold great potential in meeting the new BT.2020 color purity. However, C/N and C═O/N-based pure-green MR systems remain underdeveloped despite their synthetic accessibility. Here, a successful case is presented by merging C/N and C═O/N MR cores into a hybrid MR system, forming a new pure green emitter, DPQAO-ICz. The new molecule simultaneously maintains the MR character of its parent cores and effectively redshifts the emission to the target green region with a peak/full-width-at-half-maximum (FWHM) of 504/26 nm in toluene. The enhanced transition oscillator strength endows DPQAO-ICz with improved photoluminescence quantum yield up to 92% in the doped film. Organic light-emitting diodes (OLEDs) based on DPQAO-ICz deliver pure green emission peaking at 515 nm with FWHM of 34 nm, cutting-edge CIEy and maximum external quantum efficiency (EQE_max) of 0.68 and 25.9% among reported C/N- and C═O/N-based MR emitters. The EQE_max was boosted to 31.6% in the hyper-OLED. This study exemplifies an effective method to considerably extend the π plane to reduce the energy gap of emitters. The method also enables redshifted narrowband emission without sacrificing oscillator strength and broadening FWHM. © 2025 Wiley-VCH GmbH.