Donor–acceptor materials exhibiting deep blue emission and thermally activated delayed fluorescence with tris(triazolo)triazine

Abstract

Five luminescent donor–acceptor compounds based on the tris(triazolo)triazine (TTT) acceptor were prepared. Out of the series of emitters, TTT-3HMAT exhibits deep blue emission with CIE(x, y) < (0.16, 0.05) and a photoluminescence quantum yield (PLQY) of 0.94 in toluene. In addition, the locked-planarity of the hexamethylazatriangulene (HMAT) donors induced the highest two-photon cross-section σ² of 2928 GM, while the material also exhibited 2.9-fold enhancement in photostability compared to non-planarized triarylamines. In contrast, TTT-3TTAC undergoes thermally activated delayed fluorescence (TADF), attributed to the strongly donating and highly twisted nature of the N3,N3,N6,N6-tetra-p-tolyl-9H-carbazole-3,6-diamine(TTAC) donor. Overall, this work uncovers the potential for TTT-based dyes for two-photon imaging while further revealing the structure–property relationships needed to design TTT-based emitters as TADF materials.