Do chili peppers really make solar cells work better???


Well, capsaicin – the “hot” ingredient in chili peppers – apparently does so, according to the BBC.

From fizzy drinks to moreish crisps, many inventions are famed for their unusual and often closely guarded ingredients – but solar panels aren’t usually found at the top of that list. However, several food ingredients have proved to be unexpectedly useful when added to solar cells.

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 chilli peppers their spicy sting, has been found to improve perovskite solar cells – the devices that make up solar panels.

Adding capsaicin expands the grains which make up the active material of the solar cell, allowing it to more effectively transport electricity. More importantly, the material goes from having a deficit of electrons to having an excess, which changes how the cell operates and allows more sunlight to be converted to electricity. In essence, adding capsaicin adds electrons (which may or may not be the same effect you experience on your tongue after a particularly spicy biryani).

. . .

In 2014, I published a paper demonstrating how a compound called magnesium chloride could dramatically reduce the cost of solar energy, albeit in a different type of solar cell. Haven’t heard of magnesium chloride? Well if you’re vegan, you’ve probably consumed it at one time or another.

It’s a salt not too dissimilar to table salt (sodium chloride) and it can be recovered from sea water. It has many uses, but one of its most popular is in Japanese cooking, where it’s known as nigari and used as the coagulant for thickening tofu. My findings led to some media coverage of “tofu solar”, which was fun, and me getting called “tofu boy” at academic conferences (less fun).

. . .

Solar cell research is really a matter of materials science, which sits somewhere between physics and chemistry. The development of new solar cell technologies or processes is very labour-intensive, and the typical approach is to spend a great deal of time testing the performance of a large number of comparable but slightly altered cell designs. Solar cells are comprised of stacked layers of different materials, and it’s hard to predict what will happen to the performance of the entire structure by changing one component.

If I add something to layer A and it changes, then layers B, C and D on top of it will probably change as well. Similarly, if I change layer C, will I need to change how I made A or B? And what will then happen to D? You can probably get a sense of how hard this would be to predict, and this feeds the curiosity behind much of the innovation in this field.

Think of solar cells like cake. To find out what will happen when you add a novel ingredient, it’s far more reliable to bake it and then sample the final concoction than to try to predict what it will look and taste like before you bake it.

In the end, the food we eat, just like solar cells, is a mix of compounds. While we know capsaicin from chilli, it’s really just an organic compound, which, coincidentally, has particular properties that make it suitable for solar cell processing – as well as for spicing up a fajita.

There’s more at the link.

Hmmm . . . that being the case, I wonder whether smothering a solar panel in salsa, adding a touch of sour cream and placing it on a bed of tortilla chips would improve its performance?



  1. There's a lot of "Black Magic" involved in semiconductor manufacturing. The levels of purity the materials require is staggering, while the required amounts of "dopants" are extremely small. A small error or unintended contaminant can cause significant changes to the properties of the semiconductor being made. Process controls are critical, and at one place I worked at that made microwave diodes they could make a batch of diodes that were extremely good, and the next "identical" batch would barely work.

  2. drjim has it right.
    In the late 90's, I worked at a small company in Silicon Valley that was one of three branches. We had a small semiconductor fab that produced a patented, critical component for the main product. The fab dept lost control of the process, and the part was failing before they could finish building the system.

    The company went bankrupt before they could figure out what was being done wrong. Having observed the manager and lead in the breakroom, I suspect they had a cleanliness issue, with cross-contamination of the equipment in the fab.

Leave a comment

Your email address will not be published. Required fields are marked *