One Molecular Platform, Three Distinct Narrowband Organoboron TADF Emitters: A Divergent One-Pot Strategy From Green to Red.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters enable narrowband electroluminescence with exceptional color purity in organic light-emitting diodes (OLEDs). However, extending emission to longer wavelengths, particularly into the red region, while preserving spectral sharpness remains challenging. Here, we report a divergent one-pot borylation strategy that transforms a single 5,11-dihydroindolo[3,2-b]carbazole platform into three structurally distinct organoboron MR-TADF emitters spanning green to red. This approach harnesses competing mono- and double-borylation pathways that coexist under the reaction conditions to generate multiple emitters in a single operation. The resulting MR-TADF emitters (BN-G, BN-Y, and BN-R) exhibit ultranarrow green, yellow, and red photoluminescence with full widths at half maximum below 25 nm and near-unity quantum yields (96%-100%) in doped films. OLEDs based on these emitters achieve maximum external quantum efficiencies of up to 35.3%, with emission maxima spanning 516-601 nm. This study establishes a unified design strategy for generating multiple high-performance MR-TADF emitters from a single precursor, providing a versatile platform for the development of color-tunable narrowband optoelectronic materials.