Improved performance of electroluminescent devices based on an europium complex

Electroluminescent (EL) devices using an europium complex ${\mathrm{Eu(DBM)}}_3$ bath as the electron-transport emitting layer were fabricated. The quenching effect of the metal cathode and the unstable nature of the Eu complex under EL operation markedly influence the EL efficiency. By keeping the emitting area far from the metal cathode and partly doping the ${\mathrm{Eu(DBM)}}_3$ bath layer with a hole-transport material, the EL performance was significantly improved. Sharp-band red emissions with turn-on voltage of 3 V, brightness of 820 ${\mathrm{cd/m}}^2,$ and external quantum efficiency of 1% were achieved.