The development of chelate metal complexes as an organic electroluminescent material

The chelate metal complexes, such as tris(8-hydroxyquinolinate)aluminum (Alq/sub 3/), have excellent electroluminescent (EL) properties. Several chelate metal complexes were developed and the experimental rule of molecular design for use in an organic EL device was found. When the chelate metal complex has the structure of an inner complex sell, the EL device is fabricated by conventional vacuum-vapor deposition. This rule was applied to some chelate metal complexes, and, as a result, various complex materials could be obtained. RGB (red, green, and blue) emission was achieved using only chelate metal complexes, after successfully obtaining high-luminance blue-emitting materials, such as azomethine-zinc complex. This shows that the chelate metal complexes can be applied to full-color flat displays as an emitting material. As for durability, when Bis(10-hydroxybenzo[h]quinolinato)beryllium (BeBq/sub 2/) was used as an electron transport layer, a lifetime (initial luminance: 500 cd/m/sup 2/) of more than 3500 h, which is a practical level, was achieved in running tests. Thus, it seems that chelate metal complexes are a strong candidate as an organic EL material in practical use.