Improved efficiencies of hybrid organic light-emitting diodes using efficient electron injection layer

Hybrid organic-inorganic light-emitting diodes were developed with pristine ZnO (2.0wt%) and Cu-doped ZnO (2.0wt%) as electron injection layer and iridium(III)-bis-2-(4-fluorophenyl)-1-(naphthalen-1-yl)-1H-phenanthro[9,10-d]imidazole (acetylacetonate) [Ir(fpnpi)(2) (acac)] as green emissive layer (521nm). The pristine ZnO and Cu-doped ZnO are deposited at indium tin oxide cathode and emissive layer interface. The electroluminescent performances increased by electron injection layer-Cu-doped ZnO compared with ZnO-based device because Cu-doped ZnO injects electron efficiently result in balanced h(+)-e(-) recombination in emissive layer than ZnO-based device. The Cu-doped ZnO (2.0 %) device shows luminance (L) of 10982cd/m(2) at 23.0V (ZnO, 1450cd/m(2) at 23.0V).