Reversible single-molecule switching in an ordered monolayer molecular dipole array.

Making electronic devices using a single molecule has been the ultimate goal of molecular electronics. For binary data storage in particular, the challenge has been the ability to switch a single molecule in between bistable states in a simple and repeatable manner. The reversible switching of single molecules of chloroaluminum phthalocyanine (ClAlPc) dipolar molecules within a close-packed monolayer is demonstrated. By pulsing an scanning tunneling microscopy tip, read-write operations of single-molecular binary bits at ~40 Tb/cm(2) (~250 Tb/in(2)) are demonstrated.