Recall that semiconductors are a class of materials defined by their conductivity properties. Specifically, they have intermediate conductivity properties between those of things that conduct extremely well (like metals) and things that don’t tend to conduct well at all (insulators); this is what makes them so useful. Scientists are able to use semiconductors to control the flow of electricity in circuits, which has been crucial for the development of all of the complicated electronic devices you’re familiar with. Semiconductors can be “doped” with materials containing extra electrons, or with materials that are electron deficient, to control the direction of electron flow through the material. Semiconductors have also played a big role in developing solar energy capture devices. The amount of energy a semiconductor needs to absorb to “release” an electron such that electricity can flow can be finely tuned, allowing scientists to develop materials capable of storing solar energy (from photons of light) in the form of electricity.