The positional effect of arylamines on pyrene core in a blue fluorescent dopant significantly affecting the performance of organic light emitting diodes

Abstract

New blue fluorescent dopant materials based on pyrene moieties were synthesized by variation of the positions of N-phenylnaphthalene-1-amine functional groups to minutely control the molecular geometry and photophysical properties. A blue dopant with the functional groups at the 1, 6 position exhibited the highest photoluminescence quantum yield. 3,8-Diisopropyl-N1,N6-di(naphthalen-1-yl)-N1,N6-diphenylpyrene-1,6-diamine (DI-1,6-DAP) exhibited the best performances with a current efficiency of up to 6.89 cd/A and external quantum efficiency of 5.45% among the new synthetic dopants prepared in this study. In terms of color purity, the case of substituting arylamine groups at the 1,7 position of the pyrene core unit [N1,N7-di(naphthalen-1-yl)-N1,N7-diphenylpyrene-1,7-diamine (1,7-DAP)] was superior to the case of attaching them at the 1,6 position of the same core unit [N1,N6-di(naphthalen-1-yl)-N1,N6-diphenylpyrene-1,6-diamine (1,6-DAP)] (y < 0.098).