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 Alq3 layer in flexible organic light emitting diodes (OLEDs). The turn-on voltage decreased from 13to11V and the luminance increased from 800to3200cd/m2 at 15V as Mg is doped by 5% to Alq3 layer. In situ measurements of synchrotron radiation photoelectron spectroscopy revealed that the Fermi level moved about 0.45eV toward the lowest unoccupied molecular orbital by doping Mg to Alq3, reducing the energy barrier for electrons via promotion of the electrical and optical properties.