US Patent 7321503 Method of driving memory device to implement multiple states

A method of driving a multi-state organic memory device which includes an organic memory layer between upper and lower electrodes. The method comprises continuously applying voltages having different polarities to conduct switching into a low resistance state, and applying a single pulse to conduct switching into a high resistance state. A multi-state memory is realized using one memory device, since it is possible to gain three or more resistance states, thus significantly improving integration. The method has excellent reproducibility, and the resistance state induced by multiple pulses has an excellent nonvolatile characteristic.