Solar Tech Basics
Solar cells are devices that convert sunlight into electricity that can be used to power other items. The cells are made using semiconductors — materials that work between insulators and conductors and move electricity through them — to produce what is called the photovoltaic effect.
Whatever material the cell is made of is prepared for the effect by doping, which introduces another element into the main semiconductor to destabalize its electrons. For example, in silicon cells, boron and phosphorus are often introduced to produce p-type (when doped with boron) and n-type (when doped with phosphorus) semiconductors. These are placed very closely together cell, producing an electric field, and there is only a thin junction layer between them. The junction has a postive charge on one side and a negative charge on the other and acts as a one-way barrier.
As sunlight hits the cell, each particle of light (each photon) dislodges an electron within the n-type semiconductor layer and moves that electron through an electric current into the p-type layer. Once the current has taken the electron across the junction over to the p-type layer, that electron cannot cross the way it came. Instead, the electron will detour through an external path within the cell and this movement generates electricity.
While short and simple, this video from the Learning Lounge offers a good illustration of the concept:
Nuts & Bolts
A lot goes into making a solar cell, but two key things to know are: what kind of cell is it? and what materials is it made of?