New deep-blue emitting materials based on fully substituted ethylene derivatives

Abstract

New blue fluorescent compounds containing tetra-substituted ethylene moieties have been designed and synthesized. These materials, 1,2-di(4′-tert-butylphenyl)-1,2-bis(4′-(anthracene-9-yl)phenyl)ethene [BPBAPE, 1A], 1,2-diphenyl-1,2-bis(4′-(anthracene-9-yl)phenyl)ethene [PBAPE, 1B], 9,10-bis(4-(1,2,2-tris(4-tert-butylphenyl)vinyl)phenyl)anthracene [BTBPPA, 2A], and 9,10-bis(4-(1,2,2-triphenylvinyl)phenyl)anthracene [BTPPA, 2B], were synthesized through Suzuki and McMurry reactions. By fabricating multilayered non-doped OLED devices using these new blue materials, we achieved luminance efficiencies of 4.00 lm W⁻¹ (10.33 cd A⁻¹ at 8.1 V) for BPBAPE [1A] and 1.82 lm W⁻¹ (3.93 cd A⁻¹ at 6.8 V) for BTPPA [2B] at 10 mA cm⁻². The maxima in the electroluminescence spectra of ITO/2-TNATA (60 nm)/NPB (15 nm)/BPBAPE [1A] and BTPPA [2B] (30 nm)/Alq₃ (30 nm)/LiF (1 nm)/Al (200 nm) devices were found to be 475 and 452 nm respectively. The BPBAPE [1A] and BTPPA [2B] devices exhibited sky blue emission (0.195, 0.303) and deep blue emission (0.159, 0.135) at 10 mA cm⁻² respectively.