Achieving a high-efficiency dual-core chromophore for emission of blue light by testing different side groups and substitution positions

Hetero dual-core derivatives that combine anthracene and pyrene were systematically studied for the purpose of producing highly efficient blue light-emitting materials applicable to organic light-emitting diode (OLED) lighting. Five compounds were designed in order to (1) determine which one of the two core chromophores in a hetero dual-core moiety, if any, acts as the main contributor to the optical and electronic properties of the final compounds, (2) control the electron-donating ability of the side group, and (3) change the substitution position. 1-[1,1′;3′,1′′]terphenyl-5′-yl-6-(10-[1,1′;3′,1′′]terphenyl-5′-yl-anthracen-9-yl)-pyrene (TP-AP-TP) was used as the reference material, and four other materials, including diphenyl-[10-(6-[1,1′;3′,1′′]terphenyl-5′-yl-pyren-1-yl)-anthracen-9-yl]-amine (DPA-AP-TP), diphenyl-[6-(10-[1,1′;3′,1′′]terphenyl-5′-yl-anthracen-9-yl)-pyren-1-yl]-amine (TP-AP-DPA), diphenyl-{4-[10-(6-[1,1′;3′,1′′]-terphenyl-5′-yl-pyren-1-yl)-anthracen-9-yl]-phenyl}-amine (TPA-AP-TP) and diphenyl-{4-[6-(10-[1,1′;3′,1′′]terphenyl-5′-yl-anthracen-9-yl)-pyren-1-yl]-phenyl}-amine (TP-AP-TPA), were synthesized as model compounds. The synthesized materials showed absorption wavelength peaks at 403-410 nm in the film state and exhibited PL emissions of 458-505 nm. Also, anthracene was shown to be the main core contributing to the optical and electronic properties. Among the synthesized molecules, the TPA-AP-TP molecule, in which triphenylamine, with its optimum electron-donating ability, was substituted into anthracene, showed excellent electroluminescence (EL) performance for OLED lighting with a current efficiency of 8.05 cd A^-1, external quantum efficiency of 6.75%, and narrow EL FWHM of 53 nm.