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 (100 nm) 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 60 nm and 15 nm, respectively. The diode exhibits excellent electroluminescence (EL) properties, such as a turn-on voltage of 3.32 V, luminous efficiency of 4.41 cd/A and luminance of 6989 cd/m(2) at driving voltage of about 9 V.