Structure and process of ink-jet printed organic memory

An organic memory fabricated by ink-jet printing and thermal evaporation technique is reported. Typically, the device is formed with two buffer layers and one organic layer sandwiched between two metal electrodes. The resulting structure is glass substrate/inkjet printed silver electrode/buffer layer/organic layer/buffer layer/copper electrode positioned in sequence. For the first electrode of the device, a solution with stable dispersions of nanoparticles in a liquid vehicle was used as the printing ink. The ink contains surface modified ultra-fine particles that form stable colloids when dispersed in an appropriate solvent. This ink is jetted by a piezo ink-jet head to a pretreated glass and then thermal cured to afford a low resistive metal film. The width of each printing metal line is about 200 mu m with acceptable roughness to be used as the first electrode of an organic bi-stable device (OBD). Experimental results showed that the organic memory device can be driven by voltage modulation, which causes the nonvolatile memory effect by controlling the Cu+ ion concentration within the organic layer interposed between two metal electrodes. The memory-read operation is demonstrated when the Cu+ concentration is swept to the positive electrode as the applied voltage scans from OV to 3V. The observed on/off ratio can reach more than 10(5).