Peripheral Decoration of Multi‐Resonance Molecules as a Versatile Approach for Simultaneous Long‐Wavelength and Narrowband Emission

Abstract High device efficiency and color‐purity are the two essentials for high‐quality organic light‐emitting diodes (OLEDs). Multi‐resonance (MR) molecules show great potentials for high color‐purity OLEDs due to their sharp emission bands. However, most MR molecules exhibit emission limited from deep‐blue to green spectral region. Herein, through peripherally decorating MR emitter with electron donors, a new approach enabling the emission spectra of MR emitters red‐shift while retaining narrowband emission is demonstrated. By manipulating the numbers and electron‐donating abilities of the peripheries, the first narrowband yellow emitter with emission maxima of 562 nm and a full‐width at half‐maximum (FWHM) of 30 nm is realized. Highly efficient OLEDs with an external quantum efficiency of over 24% and excellent color purity are fabricated by employing these newly developed MR molecules as emitters.