Fabrication of highly efficient organic electroluminescent devices

Abstract

Efficient organic electroluminescent (EL) devices were fabricated by using a highly fluorescent aluminum complex, tris(4-methyl-8-quinolinolato)aluminum(III) $({\mathrm{Almq}}_{\mathrm{3}}\mathrm{),}$ as an emitter layer. In addition to using this complex, a multilayer device structure, consisting of a hole-injecting layer, a hole transport layer, a dye-doped ${\mathrm{Almq}}_{\mathrm{3}}$ emitting layer, and an electron transport layer, was employed in order to reduce the driving voltage as well as to maximize carrier recombination efficiency. From this device, a maximum luminance of over $\text{140\hspace{0.17em}000\hspace{0.5em}}{\mathrm{cd/m}}^2$ and an external quantum efficiency of 7.1% was observed, which is the highest efficiency ever reported for organic EL devices.