Bilayer memory device based on a conjugated copolymer and a carbon nanotube/polyaniline composite

A write-once read-many- times (WORM) memory device based on two layers of electroactive polymers sandwiched between an aluminum electrode and an indium-tin-oxide (ITO) electrode was fabricated. The electroactive polymer bilayer consisted of a conjugated copolymer film of 9,9-dihexylfluorene and Eu-complexed benzoate (P6FBEu) and a composite film of soluble self-aligned carbon nanotubes/polyaniline (PAN + CNT). At CNT contents above 1 wt %, the bilayer WORM memory device exhibited a low turn-on voltage of similar to 2 V and a high ON/OFF current ratio of 105, in comparison to a turn-on voltage of 3.8 V and an ON/OFF current ratio of 103 for the corresponding CNT-free ITO/PAN/P6FBEu/Al bilayer device. The ON and OFF states endured up to 106 read cycles at a read voltage of 1 V. The introduction of the PAN + CNT composite film as an electroactive layer in the memory device has resulted in a reduction in switching voltage, as well as an increase in ON/OFF current ratio, compared to those of the CNT-free single-layer and bilayer devices. (C) 2008 The Electrochemical Society.