Memory effect and negative differential resistance in tris-(8-hydroxy quinoline) aluminum/bathocuproine bilayer devices

Memory effect and negative differential resistance (NDR) were observed in simple tris-(8-hydroxyquinoline) aluminum/bathocuproine (BCP) bilayer devices. The devices could be switched from a low conductance state to a high conductance state when a negative bias was applied and could be restored to an OFF state when a positive bias was applied beyond the NDR region. The memory effect is nonvolatile, and an ON/OFF ratio of over 103 was achieved. The memory effect was observed only in the presence of both Alq3 and BCP layers, and the NDR is attributed to the defects formed in the BCP layer upon evaporation of an Al cathode.