Red- and white-emitting organic light-emitting diodes based on trimetallic dendritic europium (III) complex: Eu3(DBM)9(TMMB)

The photoluminescence (PL) and electroluminescence (EL) properties of a trimetallic dendritic europium (III) complex containing three metal cores as branching centers, tris(dibenzoylmethanato) (1,3,5-tris[2-(2′-pyridyl)benzimidazoly]methyl-benzene)-europium (III) (Eu3(DBM)9(TMMB)), have been investigated and reported. Red and white emissions have been acquired in the four EL devices of device A–D. Characteristic red emission peaking at 613 nm with four shoulder bands due to the 5D0 → 7Fj (j = 0–4) transitions of Eu3(DBM)9(TMMB) is observed in devices A–C. Device D with a simple non-doping device structure showed a white emission band. Also, the optical and the electrochemical properties of Eu3(DBM)9(TMMB) have been characterized to possess a better understanding on the intramolecular energy transfer process. It is concluded that dendritic structure with three DBM ligands as “absorption antennas” facilitates the energy absorption and transportation of the complex.

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► A trimetallic dendritic europium (III) complex has been synthesized.
► Characteristic red emission peaking at 613 nm is observed in devices.
► The intramolecular energy transfer process has taken place.
► DBM as “absorption antennas” facilitates the energy absorption and transportation.