Metal-Alq(3) complexes: The nature of the chemical bonding

Alq(3) (tris(8-hydroxyquinolino)aluminum) is the most widely used electrolu minescent molecule in organic light-emitting devices. An urgent strong need exists currently to understand its chemistry and its reactivity, especiall y to those metals that constitute the cathodes commonly used. Complexes wit h single metal atoms are expected to form in metal-doped Alq3 layers as wel l as at several stages of the functioning of the device. These, however, el ude characterization via experiment only. The present study provides such a characterization by means of a series of calculations using density functi onal theory with gradient-corrected functionals of complexes with Li, Al, a nd Ca. Very clear results emerge that allow us to understand the nature of the interaction of the organic with such metal atoms and to identify the co mmon as well as the metal-specific electronic and structural characteristic s of each of them. Moreover, these calculations shed light on the specific and non-trivial effects that the formation of these chemical species can ha ve on the intrinsic properties of the organic material.