White polymer light-emitting diodes based on poly(2-(4′-(diphenylamino)phenylenevinyl)-1,4-phenylene-alt-9,9-n-dihexylfluorene-2,7-diyl) doped with a poly(p-phenylene vinylene) derivative

Abstract Efficient white polymer light-emitting diodes based on the polymer blend of poly(2-(4′-(diphenylamino)phenylenevinyl)-1,4-phenylene- alt -9,9- n -dihexylfluorene-2,7-diyl) doped with poly{2-[3′,5′-bis(2ʺ-ethylhexyloxy) benzyloxy]-1,4-phenylenevinylene}- co -poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) were fabricated. The electroluminescence (EL) spectrum is easily controlled by changing the dopant concentration. A white light emission was realized on the device with the dopant concentration of 0.194‰ and the emission light is less sensitive to the applied voltage in a wide voltage range. The maximum luminance and the maximum EL efficiency of the single-layer device were 2330 cd/m 2 and 0.29 cd/A, respectively. By introducing an Alq 3 layer as an electron transporting and hole blocking layer, the overall performance of the double layer device was dramatically improved, the maximum luminance and the maximum EL efficiency reached 3300 cd/m 2 and 2.37 cd/A, respectively.