Wide-Range Color Tuning of Narrowband Emission in Multi-resonance Organoboron Delayed Fluorescence Materials through Rational Imine/Amine Functionalization

Establishing a simple and versatile design strategy to finely modulate emission colors while retaining high luminescence efficiency and color purity remains an appealing yet challenging task for the development of multi-resonance-induced thermally activated delayed fluorescence (MR-TADF) materials. Herein, we demonstrate that the strategic introduction of electron-withdrawing imine and electron-donating amine moieties into a versatile boron-embedded 1,3-bis(carbazol-9-yl)benzene skeleton enables systematic hypsochromic and bathochromic shifts of narrowband emissions, respectively. By this method, effective electroluminescence color tuning was accomplished over a wide visible range from deep-blue to yellow (461-571 nm), using the same MR molecular system, without compromising very narrow spectral features. Deep-blue to yellow organic light-emitting diodes with maximum external quantum efficiencies as high as 19.0-29.2 % and superb color purity could be produced with this family of color-tunable MR-TADF emitters.

Automated summary

Establishing a simple and versatile design strategy to modulate emission colors while maintaining high efficiency and color purity is challenging for MR-TADF materials. By introducing specific functional groups, it is possible to achieve fine tuning of emission colors without compromising narrow spectral features, leading to the development of high-efficiency and color-pure organic light-emitting diodes.