  Flexible solution processed memristors show different behaviour dependent on
the choice of electrode material. Use of gold for both electrodes leads to
switchable WORM (Write Once Read Many times) resistive devices. Use of
aluminium for both electrodes increases the richness of behaviour allowing both
curved and triangular memristive switching resistance memories. A comparison
device with an aluminium bottom electrode and gold top electrode only exhibited
significant memristive resistance switching when the aluminium electrode was
the cathode, suggesting that the electrode is acting as a source/sink of oxygen
anions. When the gold electrode was the cathode this electrode was deformed by
oxygen evolution. These results demonstrate that aluminium is helpful for
stabilising and promoting memristive behaviour in sol-gel TiO$_2$ devices and
that changing electrodes from aluminium to gold creates fundamentally different
device characteristics.
