Room temperature molecular electrophosphorescence detection in organic LEDs with (Gd, Eu)-β-diketonate complexes blend

Abstract In this work is reported the fabrication and characterization of the triple-layer electroluminescent organic devices using a mixture of the gadolinium and europium β-diketonate complexes [GdxEuy(TTA)3 (TPPO)2] as emitting layer. The OLED devices contained the 1-(3-methylphenyl)-1,2,3,4-tetrahydroquinoline-6-carboxyaldehyde-1,1′-diphenylhydrazone (MTCD) as hole-transporting layer and tris(8-hydroxyquinoline aluminum) (Alq3) as electron transporting layer. The electroluminescence spectra present emission narrow bands from 5D1 → 7F1,2 and 5D0 → 7F0,1,2,3,4 transitions characteristics of the Eu3+ ion. These sharp lines are overlapped with a broad band attributed to the electrophosphorescence due to the T1 → S0 transition from TTA ligand. The intermolecular energy transfer from Gd-chelate to Eu-chelate is discussed based on this electrophosphorescence appearance.