Novel aggregation-induced emission and thermally activated delayed fluorescence materials based on thianthrene-9,9′,10,10′-tetraoxide derivatives

Abstract

Two novel luminescent molecules based on thianthrene-9,9′,10,10′-tetraoxide derivatives, named tCzDSO2 and 3tCzDSO2, have been synthesized and characterized. The compound tCzDSO2 emits intense aggregation-induced emission (AIE) with a high photoluminescence quantum yields (Φ_F) of 0.92 at room temperature in the solid state. Simultaneously, by increasing the proportion of carbazole units, 3tCzDSO2 exhibits both AIE and thermally activated delayed fluorescence (TADF) in the solid state with Φ_F of 0.19 in air and 0.41 in N₂ atmosphere. The two compounds also display a bathochromic effect due to their intramolecular charge transfer (ICT) attribute. The time-dependent DFT predicted the singlet and triplet splitting (ΔE_ST) values of tCzDSO2 and 3tCzDSO2 to be 0.29 eV and 0.06 eV, respectively. The ΔE_ST of 3tCzDSO2 is small enough to allow efficient reverse intersystem crossing (RISC), leading to the TADF property at room temperature. As a result, the molecular design provides a simple and effective approach to integrate the features of AIE and TADF into one compound.