Benzo[d]imidazole-functionalized Triazatruxenes as the Emitting Materials for Solution-processed Non-doped OLEDs

Abstract Two benzo[d]imidazole/triazatruxene hybrid compounds, 5,10,15-tributyl-2,7,12-tris(4-(1-phenyl-1H-benzo[d]imidazole-2-yl)phenyl)-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole (2,7,12-TBI-TAT) and 5,10,15-tributyl-3,8,13-tris(4-(1-phenyl-1H-benzo[d]imidazole-2-yl)phenyl)-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole (3,8,13-TBI-TAT), were synthesized by the introduction of three benzo[d]imidazole (BI) moieties at 2-, 7-, 12-positions and 3-, 8-, 13-positions of the alkylated triazatruxene (TAT) core, respectively. Their thermal stabilities, photophysical and electrochemical properties were systematically investigated. These hybrid compounds exhibited good solubility as well as excellent thermal stability. Besides, the solution-processed doped and non-doped OLEDs based on the compounds were fabricated, in which the non-doped device fabricated from 2,7,12-TBI-TAT exhibited the best electroluminescence performance with a maximum brightness of 10075 cd/m2, a maximum current efficiency of 5.35 cd/A and a maximum external quantum efficiency (EQE) of 2.25%.