White electroluminescence of lanthanide complexes resulting from exciplex formation

Gael Zucchi (1) , Taewoo Jeon (1) , Denis Tondelier (1) , Dmitry Aldakov (1) , Pierre Thuéry (2) , M. Ephritikhine (2) , Bernard Geffroy (1, 3)

1 LPICM - Laboratoire de physique des interfaces et des couches minces [Palaiseau]
2 IRAMIS - Institut Rayonnement Matière de Saclay
3 LCSI - Laboratoire de Chimie des Surfaces et Interfaces

Bimetallic complexes of the visible-emitting Eu3+, Tb3+ and Sm3+ ions with 2,2′-bipyrimidine (bpm) and acetylacetonate (acac) ligands have been synthesized and crystallographically characterized. They have been found to be isomorphous with the general formula [{Ln(acac)3}2(μ-bpm)] (Ln = Eu, 1; Ln = Tb, 2; Ln = Sm, 3). Their X-ray crystal structure shows that the aromatic polyamine ligand bridges the two metal ions. These volatile complexes have been thermally evaporated to be introduced in multilayer OLEDs as dopants. In addition to the electroluminescence of the lanthanide ion, a broad emission in the yellow-green region was obtained. This resulted in white electroluminescence of the devices doped with 1 or [{Eu(tta)3}2(μ-bpm)] (4) complexes (tta = 2-thenoyltrifluoromethanesulfonato). This broad emission is shown to be caused by the formation of an exciplex between the dopant and the host matrix within the emitting layer of the devices.

Domains: Coordination chemistry; Material chemistry; Electronics; Materials

Gael Zucchi, Taewoo Jeon, Denis Tondelier, Dmitry Aldakov, Pierre Thuéry, et al.. White electroluminescence of lanthanide complexes resulting from exciplex formation. Journal of Materials Chemistry, 2010, 20 (11), pp.2114-2120. ⟨10.1039/B921740A⟩. ⟨hal-00830384⟩