Molecular electronics and neural network functions

A description is presented of electrooptical properties of iron tetrasulfonated (Fe-TsPc) and oxygen bridged silicon (SiPcO)_n phthalocyanines, where n is the number of Pc molecules organized in a stacking-ring configuration. Cyclic voltammetry alters the redox state of the adsorbed molecules and provides current-voltage characteristics describing redox currents and potentials. If one observes intensity change of the optical signal, then a light detector records optical changes. This mode of operation is an analog one and is relatively slow, since it requires intramolecular charge transfers to be performed by electrical means involving an interfacial capacitance effect. On the other hand, if intramolecular charge transfer is caused by optical methods, e.g., by illuminating molecules with lights which fall in the light absorption bands at about 330 and 660 nm, then the optical output changes in a digital fashion. In another mode of operation, the experimental results are very similar to the Hopfield energy curve, with a multiplicity of minima representing stable states of a neural network