Large conductance switching and memory effects in organic molecules for data-storage applications

We have observed a large electrical conductance switching (ON:OFF ratio=10(5)) in single-layer sandwich structures based on organic molecules at room temperature. The switching devices showed an associated memory effect for data-storage applications. We could write or erase a state and read it for many cycles. In switching devices, the active semiconductor retained its high conducting state until a reverse voltage erased it. A high conducting state arose due to restoration of conjugation in the molecule via electroreduction. Such a high ON-OFF ratio in a single layer sandwich structure, as compared to contemporary switching devices, is due to low off-state leakage current. The concept of conjugation restoration has been verified in supramolecular structures by adding donor groups to the molecule, which resulted in increased off-state current and hence lower ON-OFF ratio. Our work set a generalized example of selecting organic molecules to obtain higher ON-OFF ratio in molecular switching devices. (C) 2003 American Institute of Physics.