Enhancement of electron injection in flexible OLEDs using magnesium-doped tris(8-hydroxyquinoline) aluminum layer

We report the enhancement of electron injection using a magnesium (Mg)-doped tris-(8-hydroxyquinoline) aluminum (Alq3) layer between the Al and Alq(3) layer in flexible organic light emitting diodes (OLEDs). The turn-on voltage decreased from 13 to 11 V and the luminance increased from 800 to 3200 cd/m(2) at 15 V as Mg is doped by 5% to Alq(3) layer. In situ measurements of synchrotron radiation photoelectron spectroscopy revealed that the Fermi level moved about 0.45 eV toward the lowest unoccupied molecular orbital by doping Mg to Alq(3), reducing the energy barrier for electrons via promotion of the electrical and optical properties. (c) 2007 The Electrochemical Society.