A new europium (Eu) complex with dendron-substituted diketone ligands was synthesized and found to exhibit a photolumin-escence efficiency of 45%. Double-layer light-emitting diodes based on polymer matrices doped with the Eu complex were fabricated, An electroluminescence external quantum efficiency of 0.80% was achieved when a copolymer containing side-chain carbazole and 1,3,4-oxadiazole groups was used as the matrix. The results are analyzed in the context of Forster energy transfer.