Addressing Multiple Resistive States of Polyoxovanadates: Conductivity as a Function of Individual Molecular Redox States

The sustainable development of IT-systems
requires a quest for
novel concepts to address further miniaturization, performance improvement,
and energy efficiency of devices. The realization of these goals cannot
be achieved without an appropriate functional material. Herein, we
target the technologically important electron modification using single
polyoxometalate (POM) molecules envisaged as smart successors of materials
that are implemented in today’s complementary metal-oxide-semiconductor
(CMOS) technology. Lindqvist-type POMs were physisorbed on the Au(111)
surface, preserving their structural and electronic characteristics.
By applying an external voltage at room temperature, the valence state
of the single POM molecule could be changed multiple times through
the injection of up to 4 electrons. The molecular electrical conductivity
is dependent on the number of vanadium 3d electrons, resulting in
several discrete conduction states with increasing conductivity. This
fundamentally important finding illustrates the far-reaching opportunities
for POM molecules in the area of multiple-state resistive (memristive)
switching.