EFFECTS OF AL, AG, AND CA ON LUMINESCENCE OF ORGANIC MATERIALS

Organic materials have been demonstrated to have the necessary attribu tes for display applications. In typical organic light emitting device s, metallic electrodes are used to inject charged carriers into the or ganic electroluminescent (EL) medium. We report severe photoluminescen ce (PL) quenching of organic thin films comprising the most useful mat erials, namely 1,4-bis[4-(3,5-di-tert-butylstylyl)styryl]benzene (4PV) , upon sub-monolayer deposition of Al, Ag, and Ca in an ultrahigh vacu um environment. The severity of the luminescence quenching, which depe nds on the type of metal used, can greatly affect the EL device perfor mance. For example, a sub-monolayer coverage of the various metals on a 300 Angstrom 4PV thin film can reduce the PL by as much as 50%. Depo siting the 4PV layer onto a metal substrate also exhibits PL quenching . An exciton diffusion length of 200 Angstrom can be estimated from th e quenching data. (C) 1997 American Vacuum Society.