Data-storage devices based on layer-by-layer self-assembled films of a phthalocyanine derivative

Abstract

An organic dye, namely nickel phthalocyanine, has been used in data-storage devices. A "high state" has been written by applying a voltage pulse. The state of the device has been "read" by applying a small probe voltage. The dye embedded in an inert polymer matrix retained the high state for more than an hour, which can be refreshed or erased at will. Hysteresis-type behaviour has been observed in the current-voltage characteristics. The space charges at the metal/semiconductor interfaces, stored under the voltage pulse, have been found to control the charge injection and hence the current in these devices. The formation of space charges near the interfaces, and relaxation have been studied in the data-storage devices. The space charges' slow relaxation process has been shown to result in the memory device applications of the semiconducting dyes.