Study on a star-shaped europium complex: Synthesis, photophysical properties and organoelectronic performances

Abstract

In this paper, we report the synthesis and characterization of a star-shaped hexdentate diamine ligand of BBIM, where BBIM stands for 1,1′-(5-((2-(pyridin-2-yl)-3H-indol-3-yl)methyl)-1,3-phenylene)bis(methylene)bis(2-(pyridin-2-yl)-1H-benzo[d]imidazole), and its corresponding Eu(III) complex of Eu3(DBM)9BBIM with 1,3-diphenyl-propane-1,3-dione (DBM) as the first ligand is also synthesized, resulting in a promising red emitter. The molecular structure, photophysical properties, and electrochemical characters of the red emitter are investigated in detail. Eu3(DBM)9BBIM shows a star-shaped structure in ground state, with a high photoluminescence yield of 0.64 and a short excited state lifetime of 120μs. Further analysis connects the short excited state lifetime with its highly distorted molecular structure. In addition, Eu3(DBM)9BBIM possesses a high thermal decomposition temperature of ∼315°C. Finally, electroluminescence (EL) and photovoltaic (PV) devices using Eu3(DBM)9BBIM as organic functional material are fabricated, a white emission with maximum luminance of 168cd/m2 from the EL device and a maximum power conversion efficiency of 1.05% from the PV device are realized.