Narrowband Hydrocarbon Emitters Enabled by Stereo‐Locked Through‐Space Interactions

High‐purity emitters with a narrowband emission are a critical requirement for next‐generation displays and lighting, yet it remains a formidable challenge for purely organic materials, particularly in the pure‐violet region. Herein, a general molecular design strategy based on the “stereo‐lock” concept, represented by diarylbenzene derivatives solely from carbon and hydrogen, is presented. This strategy effectively suppresses intramolecular C─C/C─H stretching and attenuates vibronic coupling via intramolecular through‐space interactions between two aryl groups, yielding a record full width at half maximum (FWHM) of merely 6 nm at 80 K from a single molecule. In the solid state, their aggregates with intermolecular positive exciton coupling induce quantum interference that selectively quenches the v 0‐0 transition, resulting in an FWHM of 17 nm at room temperature. Leveraging this synergy, diarylbenzene‐based OLED devices with pure‐violet electroluminescence with an 18 nm FWHM and a CIE coordinate of (0.165, 0.022) are achieved. This stereo‐lock architecture circumvents the fundamental limitation of vibronic coupling in pure hydrocarbons and addresses the absence of high‐color‐purity violet OLEDs, establishing a powerful and versatile design paradigm for narrowband emitters.