Red and Near-Infrared Electroluminescences from Metal-Free Phthalocyanine

Organic light emitting diodes are fabricated based on metal-free phthalocyanine (H2Pc) doped into tris-(8-hydroxyquinoline) aluminium (Alq3). The device structure is ITO/NPB (30 nm)/Alq3: H2Pc(30 nm)/BCP(20 nm)/Alq3(20 nm)/Al. In the light-emitting layers, H2Pc concentrations are varied from 0 wt% to 100 wt%. The emissions around 708 nm and 800 nm appear at low concentrations, while the emissions around 910 nm and 930 nm appear at high concentrations. The emissions around 708 nm and 800 nm are from H2Pc monomers. The emissions around 910 nm and 930 nm are from H2Pc aggregates. The dominant mechanism in the doped devices is direct charge trapping.