Deep-red/NIR AIEgens based on electron-withdrawing dithiafulvalene-fused benzothiadiazole for solution-processed non-doped OLEDs

Abstract

Deep-red (DR)/near-infrared (NIR) emitters have extensive applications in bioimaging and flexible optoelectronics. However, it is challenging to design efficient DR/NIR emitters with high photoluminescence quantum yields (PLQYs), especially in the solid state, due to the energy gap law. A common strategy to develop new acceptors is to construct donor–acceptor luminogens with fine-tuned molecular structures. Nevertheless, new acceptors that are suitable for constructing highly efficient DR/NIR emitters are still rare. Herein, by utilizing cyano-substituted dithiafulvalene fused benzothiadiazole (BSMCN) as the acceptor and triphenylamine derivatives as donors, three BSMCN-based molecules, respectively, named 2TB, 2MTB, and 2MOTB, are rationally designed and efficiently synthesized. All three compounds exhibit aggregation-induced emission properties with their emission wavelengths extending from the DR to NIR region. Moreover, when applied in solution-processed non-doped devices, 2TB exhibits a high external quantum efficiency of 4.9% at a wavelength of 664 nm, demonstrating the great potential of BSMCN-based DR/NIR AIEgens in developing non-doped OLEDs.