The unexpected ingredients that improve solar cells

 A number of kitchen cabinet ingredients have found unlikely uses for improving the efficiency of solar panels. Solar cell scientist John Major explains why.

From fizzy drinks to sweeter chips, many inventions are famous for their unusual and often closely guarded ingredients, but solar panels aren't usually at the top of this list. However, some food ingredients were unexpectedly useful when added to solar panels.

Depending on what you like to eat, there's a good chance you can find at least one of them at home. Capsaicin, the chemical that gives chili peppers a sharp sting, has been found to improve perovskite solar cells – the devices that make up solar panels.

The addition of capsaicin expands the grains that make up the active material of the solar cell, allowing it to transport electricity more efficiently. More importantly, the material goes from a shortage of electrons to an excess, which changes how the cell works and allows more sunlight to be converted into electricity. Essentially, adding capsaicin adds electrons (which may or may not be the same effect you experience on your tongue after a particularly sharp biryani).

Why would you even think of adding chili peppers to a solar panel?

The cells laced with capsaicin are among the most effective that have been reported. Adding this chemical from chili peppers may actually be a way to boost the performance of solar panels, rather than a trick to grab headlines.

But why did you decide to add chili peppers to the solar panel in the first place? Unfortunately, the researchers didn't share their thought process. But I have a form in this area as well.

New "Gold Rush" for Green Lithium

Batteries that could make power plants obsolete

Why do some bikers work and others don't

In 2014, I published an article demonstrating how a compound called magnesium chloride can dramatically reduce the cost of solar energy, albeit in a different type of solar cell. Never heard of magnesium chloride? Well, if you're a vegan, you've probably consumed it at one time or another.

It is a salt not too different from table salt (sodium chloride), and can be extracted from seawater. It has many uses, but one of the most popular is in Japanese cooking, where it is known as nigari and is used as a coagulant to thicken tofu. My findings led to some media coverage of "tofu solar", which was funny, and I was called " tofu boy” at academic conferences (less funny).

A popular ingredient in Japanese cooking, nigari, has also shown promise in making solar panels work better – and it tastes good, too (Credit: Alamy)

A popular ingredient in Japanese cooking, nigari, has also shown promise in making solar panels work better – and it tastes good, too (Credit: Alamy)

Does this mean that food chemicals are particularly well tolerated in solar cell research? Not really. This overlap has more to do with the overlap between food and chemistry and the "what if" approach that many materials scientists follow.

Think of solar panels like a cake. To find out what happens when you add a new ingredient, it's much more reliable to bake it and then try the finished mixture

You might think that most solar cell research is done by physicists. This is partly true – I am one of them myself – but the research approach has little to do with the work of particle physicists at the Large Hadron Collider or cosmological research. These areas usually revolve around heavy computing and theoretical work. In other words, a lot of time staring at blackboards.

Solar cell research is really a material science that lies somewhere between physics and chemistry. Developing new solar cell technologies or processes is a very time-consuming process, and the typical approach is to spend a lot of time testing the performance of a large number of comparable but slightly modified cell designs. Solar cells are made up of multi-layered layers of different materials, and it is difficult to predict what will happen to the performance of the entire structure when a single component is changed.

If I add something to layer A and it changes, then layers B, C, and D on top of it will probably change too. Similarly, if I change layer C, will I need to change how I did A or B? And then what will happen to D? You can probably understand how difficult it would be to predict this, and it feeds the curiosity behind many innovations in this area.

We shouldn't be surprised if more of the compounds found in food end up in solar panels in the future, as they are often organic compounds with beneficial properties (Credit: Alamy)

We shouldn't be surprised if more of the compounds found in food end up in solar panels in the future, as they are often organic compounds with beneficial properties (Credit: Alamy)

Think of solar panels like a cake. To find out what will happen when you add a new ingredient, it is much more reliable to bake it and then taste the finished mixture than to try to predict how it will look and taste before baking.

After all, the food we eat, like solar panels, is a mixture of compounds. Although we know capsaicin from chile, it's actually just an organic compound that, coincidentally, has special properties that make it suitable for processing solar cells, as well as for seasoning fajita.

For my part, I developed a process for using magnesium chloride and only later found out when I came to write an article that it was used in tofu. Unfortunately, I wasn't inspired by the vegan food aisle. So these approaches aren't as weird and wacky as they sound when you first read about them. There is usually some initial logic based on the inherent chemistry of these compounds, and these flights of scientific imagination often lead to interesting breakthroughs.

So if you read an article in the near future about solar panels immeasurably improved by the addition of nutmeg or something else, believe that it was done as a result of conscious curiosity about the likely effect, not boredom and the impending bestseller date.