New deep blue fluorophores based on benzo[d]thiazole group as acceptor core: Theoretical, synthesis, photophysical and electroluminescent investigation

Deep-blue organic emitters have attracted considerable attention from both industrial as well as academic research in organic light-emitting diodes (OLEDs). In this context, three novel deep blue fluorophores based on benzothiazole 2-(4'-(1,4,5-triphenyl-1H-imidazole-2-yl)-[1,1'-biphenyl]-4-yl)benzo [d]thiazole (PHBISN), 2-(4'-(1-(4-(tert-butyl)phenyl)-4,5-diphenyl-1H-imidazole-2-yl)-[1,1'-biphenyl]-4-yl)benzo [d]thiazole (PTBISN) and 2-(4'-(4,5-diphenyl-1-(3-(trifluoromethyl)phenyl)-1H-imidazole-2-yl)-[1,1'-biphenyl]-4-yl)benzo [d]thiazole (m-CFBISN) were designed and synthesized. The fluorophores were structurally characterized and a detailed computational study reveals the compounds with wide energy gap (> 3eV). The thermal properties, photophysical and electronic properties were systematically investigated. Photoluminescence and electroluminescence study shows fluorophores with deep blue emission. Novel synthesized fluorophores exhibit good performance for deep-blue solution-processed OLEDs. The doped device based on PTBISN shows the highest performance with deep blue electroluminescent and maximum EQE 1.5% with CIE color coordinates of (0.15, 0.08), which is near to the blue standard (0.14, 0.08) of the National Television System Committee (NTSC).