A tris(8-hydroxyquinoline) aluminum-based organic bistable device using ITO surfaces modified by Ag nanoparticles

A tris (8-hydroxyquinoline) aluminum (Alq₃)-based organic bistable device (OBD) using Al electrode and ITO electrode modified by Ag nanoparticles (NPs) was reported. The OBD exhibits high ON/OFF switching ratios in the range of 10²-10³ and long retention time over 10⁴ s. The influence of the Ag NPs densities, as well as the Alq ₃ film thickness on the switch performance current-voltage (I-V) of the OBDs was studied. Correlation between filament formation mechanism and charge storage mechanism was observed by analysing the I-V characteristics of OBDs with different Alq₃ film thickness. As for the Alq₃ film with thickness of 300 nm, the trapping effect of Ag NPs leads to both ON and OFF states for OBD; for 100 nm thick Alq₃ film, the effect of filamentation dominates in the ON and OFF states of OBD. For the case of 200 nm thick Alq₃ film, however, the ON state results from the filamentation effect, while trapping effect is responsible for the OFF state. In addition, the diffusion effect of Al atoms in Alq₃ film in the devices was discussed and was expected to explain this thickness-dependence relationship.