インドロカルバゾールをベースとした電荷移動とマルチレゾナンス特性を統合した効率的なスカイブルー狭帯域熱活性化遅延蛍光エミッター

Organic emitters with narrow-band emission are of great significance for realizing high-definition organic light-emitting diodes (OLEDs). The multiple-resonance thermally activated delayed fluorescence (MR-TADF) is constrained by slow reverse intersystem crossing (RISC). Herein, we proposed a strategy to adjust their excited state natures by linking MR units with an indolocarbazole (ICz) donor. The designed emitters, namely, ICz-BN and tICZ-BN, showed the advantages of MR-TADF with a narrow full-width at half-maximum (FWHM) along with a minimal triplet-singlet energy gap (ΔE_ST). The fast radiative decay (>10⁷ s^-1) and large RISC rate constants (k_RISC > 10⁵ s^-1) were realized. The maximum external quantum efficiency (EQE_max) of 28.5% and 24.7% were achieved along with the FWHM of 36 and 34 nm and emission peaks of 491 and 489 nm. The tICz-BN-based device exhibited good resistance to concentration quenching. This strategy provides a feasible approach for designing high-efficiency narrow-band sky-blue TADF emitters.