Solar cells work by absorbing light waves, harnessing the photons’ energy to knock electrons off of atoms, thereby generating electricity. Here’s the thing, though: different light waves have different levels of energy, and current solar cells can’t use low-frequency wavelengths of light.
That’s because most solar cells are made using silicon, which isn’t able to “respond to light less energetic than the near infrared.” Although low-frequency waves contain less energy than light with higher frequencies, finding a way for solar cells to absorb all light waves could drastically improve the efficiency of solar panels. Fortunately, there are two new innovations that could help solar cells do just that.
The first solution, published in Nature Photonics, is to use minuscule semiconductors — called quantum dots — to absorb this low-energy light. The quantum dots then use oxygen to upconvert the light waves into higher frequencies, and, voila, you’ve got light that a solar cell can now turn into power.
The other new innovation, published in Nature Energy by a team of researchers based in Japan and China, involves optimizing not the light but the solar cells themselves. Using a type of material called perovskite, these researchers are developing the next generation of solar cells. Perovskites are flexible, lightweight, and — crucially — cheaper to make than the silicon cells currently used. Perovskites have an issue, though: it’s tough to make large solar cells from them.
The researcher’s solution is to use multiple layers of the material in making larger solar cells, keeping energy loss to a minimum, and reducing the risk of toxins leaking from the cells. The next step for the researchers is to test the material on larger panels.