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 Alq3 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.