When you hear the word organic, what do you think of? Whole Foods? Healthy eating?
And when you hear the term organic electronics … now what do you think?
In scientific parlance, “organic” refers not to something grown without fertilizer, but to something that contains carbon. This includes all living things, like us. Organic electronics, then, are electronics with parts created using carbon-based materials, unlike the traditional silicon.
Why use carbon?
There are a number of attractive benefits of plastic electronics that keep scientists interested in researching them. The finished products are light, thin to the point of being transparent, and much more flexible than traditional devices. They are also much cheaper to make and don’t require specialized plants to manufacture in the same way that traditional computer chips do. Since scientists are still working on conducting properties of these materials, the process is still in its early stages, as compared to traditional electronics — especially because silicon is a better conductor than carbon.
If you think back to your basic electricity lessons, things are conductors, meaning they carry electricity really well, semiconductors, meaning they can carry some electricity but not nearly as much, or insulators meaning they don’t carry electricity. Silicon works well in electronics because it carries electricity really well. Carbon does not conduct electricity like silicon, so using carbon in electronics means figuring out a way to conduct electricity better.
This is where scientists in Russia and Germany have made recent scientific progress. Organic electronics are also called plastic electronics, because the materials that make the circuits are usually printed onto sheets of plastic. This plastic is made up of large molecules called polymers. As mentioned before, these polymers are only semiconductors. So scientists add substances called dopants, which make it easier for electricity to travel through the polymers. Traditionally the dopant for plastic electronics has been fluorine. But the European scientists decided that they wanted to discover an entirely new dopant, and so they did. They discovered that a previously known molecule called -radialene successfully transforms polymers into better conductors.
How it works
If you remember back to your basic lessons on electricity again, you’ll remember that electricity is created when electrons move between different atoms. Fluorine serves as a good dopant for polymers because it pulls electrons away from the central part of a molecule and move them to the fluorine atom. -radialene has relatively empty orbitals (space where the electrons hang out) meaning that it can also easily pull electrons away from other molecules in the polymer.
But there are dozens of other molecules that probably have empty orbitals, right? Why not use those? It turns out that -radialene’s structure also combines in a really interesting and suitable way with the polymers that it is printed onto. If electricity is formed by transferring electrons between atoms, those atoms have to be touching for the electrons to transfer. This was a problem with some of the other materials that the researchers tried as dopants, because they would crystalize and lose contact with the polymers that they were supposed to be in contact with. The structure of -radialene is different, though, because it integrates really well into the existing crystal structure of the polymers that the scientists used, instead of forming its own crystals. In other words, its structure only enhanced its natural ability to pass electrons.
Since these devices can be printed onto see-through sheets, and can conduct electricity, they may be most useful in combination with light in various ways. Scientists envision them as a key part of solar panels that might greatly reduce their cost, or as a part of organic light fixtures. Plastic devices are kind of revolutionary in the realm of electronics and technology. It’ll be interesting to see what comes of this in the future, especially if solar energy becomes a major source of energy.