EXCITON DYNAMICS IN AN AROMATIC DIAMINE AT THE INTERFACE WITH 8-HYDROXYQUINOLINE ALUMINUM

Exciton dynamics parameters such as diffusion length, l(d), and surfac e quenching velocity, upsilon, in an amorphous film of an aromatic dia mine (TPD) have been measured utilizing both the quenching effect exer ted on its fluorescence by a thin layer of 8-hydroxyquinoline aluminum (Alq(3)) deposited on the film as well as the exciton detector layer radiative emission itself. It is found that l(d) = (30 +/- 10) nm and upsilon = (2 +/- 1) x 10(3) cm/s. Using independent data on the intrin sic lifetime in TPD yields the diffusion coefficient of excitons D = ( 5 +/- 1) x 10(-3) cm(2)/s. The results are discussed in connection wit h the operation mechanism of the double-layer electroluminescent struc ture based on the TPD/Alq(3) junction.