A novel D-A-D-A-D type molecule based on substituted dihydroindolo [3, 2-b] carbazole with large two-photon absorption cross section and excellent aggregation-induced enhanced emission property

Two novel D-A-D-A-D type molecules T1 and T2 based on substituted dihydroindolo [3, 2-b] carbazole with large two-photon absorption (2PA) cross section and excellent aggregation-induced enhanced emission (AIEE) property have been synthesized and characterized. Both compounds emit weakly fluorescent in THF, while a significant AIEE property is observed in water/THF (v/v 50%/50%) for T1 and water/THF (v/v 90%/10%) for T2 with a sharp increase in fluorescence intensity. The solid fluorescence of T1 and T2 is located at 575 nm and 588 nm, and their quantum efficiencies are determined to be 3.2% and 5.8%, respectively. The corresponding 2PA cross section values for T1 and T2 at 800 nm are 867 GM and 1300 GM by the open-aperture Z-scan technique. These excellent performances of both compounds make them as attractive alternatives for biophotonic and optoelectronic applications.