Voltage reduction in organic light-emitting diodes

For practical applications, it is important to operate organic light-emitti ng devices at low voltages and low power consumption. When both the cathode and anode are perfectly injecting, low electron mobility in electron-trans port materials, such as tris-(8-hydroxyquinoline)aluminum (Alq), becomes a limiting factor on voltage reduction. In this letter copper phthalocyanine (CuPc) is replaced for Alq as an electron-transport layer, and interfacial modification is utilized to enhance electron injection from the CuPc electr on-transport layer into the Alq emissive layer. The outcome of this structu re significantly facilitates electron transport through the organic materia ls, thus resulting in substantial reduction in operating voltages and power consumption. (C) 2001 American Institute of Physics.