Efficient Top-Emitting Polymer Light-Emitting Diodes Using Chromium as Anode

We demonstrate a high efficiency top-emitting polymer light-emitting diode (TPLED) with chromium (Cr) taking as the anode. The TPLED structure is Cr/poly-3, 4-ethylenedioxythiophene (PEDOT:PSS)/poly 2-(4-3',7'-dimethyloctyloxy)-phenyl-p-phenylenevinylene) (P-PPV)/Ba/Ag. The Cr (100nm) anode is prepared by sputter-depositing in a vacuum chamber. It is found that the device emissive properties are affected dramatically by the thickness of both PEDOT:PSS and the Ag cathode. Optimized thicknesses of PEDOT:PSS and Ag layer are 60nm and 15nm, respectively. The diode exhibits excellent electroluminescence (EL) properties, such as a turn-on voltage of 3.32V, luminous efficiency of 4.41cd/A and luminance of 6989cd/m² at driving
voltage of about 9V.