A Photoswitch made using just one Photosensitive Molecule

A Photoswitch made using just one Photosensitive Molecule
Schematic of a graphene-diarylethene-graphene junction that highlights the expansion of the molecular bridge by methylene groups. Credit: (c) Science (2016). DOI: 10.1126/science.aaf6298

Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light. The term photosensitivity refers to a sensitivity to electromagnetic radiation, particularly light. The particular effect considered as a change in refractive index persuaded by exposure to light.

A photoswitch, or photo-electric switch, is a sensor that detects the presence in or change of light, for example, Azobenzene. Photoswitch is one type of molecular machine that can switch between minimum two distinct thermodynamically stable forms. It is because of using of an external stimulus.

These photoswitches can be used in several places from scientific applications to residential light timers.

A team of researchers with members from institutions in China and the U.S. has successfully developed a photo switch from a single photosensitive molecule. They did some changes in previous versions of the switch that permits it to perform successfully for an entire year.

Scientists are looking for to develop fastest computers. For that purpose, they want some ways to make them smaller. The smaller the parts, the less distance information in such a machine must travel. Instead of electricity, they have preferred to use light to carry information. It is because it travels much faster. For this, several teams have attempted to create single molecule switches that can be turned on and off by exposure to light.

Before this, such attempts have not worked well tills now because switches have often become tight. Therefore, they lasted only for few hours, days or weeks.

In this new research, researchers have improved a previous technique by repairing a sticking problem. They just not only fixed the problem but have created a switch that was able to operate for over a year.

One of the previous attempts to use a single photosensitive molecule results in failure because of the tightening of the molecules in a single state. When it is open, it allows electrical conduction and during closed condition, it acts as an insulator. Here, the problem was unwanted interactions that occur between the electrode and the molecule.

To fix this problem, scientists placed three Methylene groups between a Graphene electrode and the molecule. This prevents the interactions from occurring. This results in a photoswitch can be turned ON due to exposure to normal light and can be turned OFF by exposing it to UV light.

The team has developed 46 such switches. All switches operate hopefully and dutifully by turning on and off on demand. All of the switches perform successfully for over a year.

The team is now processing of looking closer at their switches to learn more about their quantum properties. They also planning to check whether it might be possible to combine such switches to create multi-level switching devices.