Researchers have created the most efficient single-molecule diode ever.
Diodes are common in everyday electronic devices, in which they control the current by allowing it to flow in one direction while blocking it in the opposite direction. The researchers, working at the University of Barcelona (UB) and IBEC, have created one of just 1 nanometer in size with a rectification ratio – the ratio of the current that flows in one direction compared to the other – several orders of magnitude higher than previously.
Image: Single-molecule diode formed by sandwiching a molecule between gold and silicon electrodes
The research, which appeared in Nature Communications this month, addresses an emerging problem: that scientists and engineers are approaching the very limit to which they can physically downsize electronic components any further. “To reach the next level of miniaturization, we have to use individual molecules as the active components of circuits,” says Ismael Díez-Pérez, associate professor at the University of Barcelona and UB and senior researcher at IBEC, who led the project.
The method sandwiches an organic molecule between two nano-electrodes, all connected together in a circuit barely 1 nanometer long. The resulting single-molecule diode is smaller and way more efficient than ever before. “This approach will let us assemble thousands of billions of diodes on a tiny silicon chip,” explains Ismael.
The new nanoscale molecular diode can allow 4000 times more current to pass in one direction than the other, a performance that’s comparable to the diodes typically used today, but at a much smaller scale. The team is now working on achieving an even higher current rectification ratio and increasing the lifetime of these single-molecule circuits to bring us a step closer to achieving single-molecule devices.
Aragones, A. C. et al. Single-molecule electrical contacts on silicon electrodes under ambient conditions. Nat. Commun. 8, 15056 doi: 10.1038/ncomms15056 (2017).