December 17, 2007 – Researchers at Taiwan’s National Chung Hsing U., working with the Industrial Technology Research Institute, say they have created a nonvolatile organic memory device (16b), made stable by using gold nanoparticles mixed with a polymer.
Organic memory devices tend to break down after many read-write cycles, as well as prolonged exposure to air, the scientists explain in a statement. Other nonvolatile memory devices used plastics and other flexible carbon-based chemicals to simplify production and lower costs.
In the new devices, a mixed combination of gold nanoparticles and a polymer, dubbed “PCm,” is wedged between two aluminum electrodes. In a dormant state the structure produces little current, but with a 2V voltage the current jumps 10,000-fold — presumably because some electrons hopping from one nanoparticle to another get trapped, providing a conductive path to make the device functional, they note. Smaller voltages will carry and store the higher current (i.e, the “1” stage); the bit can be wiped away by applying a negative voltage.
Adding the gold nanoparticles stabilizes the organic memory and helps it endure up to 1000 switches, retaining data for roughly 10 days, though theoretically retention times can reach 30 days, according to the original report in Cellular-News. Instead of clumping together, the gold nanoparticles are connected to polymer chains that “act as fingers that get entangled with the host polymer,” noted prof. Zingway Pei, ensuring stability even if high-voltage stress is applied.
The university and ITRI plan to incorporate the device into smart cards, with other possible use in RFIDs and flexible displays for mobile devices.