科研之友
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摘要
Rationally tuning the emission position and narrowing the full width at half‐maximum (FWHM) of an emitter is of great importance for many applications. By synergistically improving rigidity, strengthening the resonant strength, inhibiting molecular bending and rocking, and destabilizing the HOMO energy level, a deep‐blue emitter (CZ2CO) with a peak wavelength of 440?nm and an ultranarrow spectral FWHM of 16?nm (0.10?eV) was developed via intramolecular cyclization in a carbonyl/N resonant core (QAO). The dominant υ0‐0 transition character of CZ2CO gives a Commission Internationale de I’éclairage coordinates (CIE) of (0.144, 0.042), nicely complying with the BT.2020 standard. Moreover, a hyper‐fluorescent device based on CZ2CO shows a high maximum external quantum efficiency (EQEmax) of 25.6?% and maintains an EQE of 22.4?% at a practical brightness of 1000?cd?m?2.(#br)A multi‐resonance emitter using intramolecular cyclization endows BT.2020‐compliant deep blue emission with an ultranarrow full width at half maximum (FWHM) of 16?nm and CIE coordinates of (0.153, 0.042) in toluene, thus achieving a high external quantum efficiency of 25.6?% in a hyper‐fluorescent organic light‐emitting diode.
