An alkylated europium(III) complex for photoelectric devices

A novel long alkyl chain-containing Eu(III) complex, tris(α-thenoyltrifluoroacetonato)(1-octadecyl-2-(2-pyridyl)benzimidazole)europium(III), Eu(TTA)3(L18), was designed for electroluminescent (EL) devices. The complex exhibited a low melting point and a large temperature difference between the melting point and onset decomposition compared to a shorter alkyl chain (ethyl) analogue. By vacuum deposition technique, a two-layer ITO/TPD/Eu(TTA)3(L18)/Al and a three-layer ITO/TPD/Eu(TTA)3(L18)/AlQ/Al EL device were fabricated and EL properties of the devices were studied. The two devices gave dominant red light emission from the europium complex with maximum luminance efficiency comparable to the two-layer device made of the short alkyl chain congener.