Silicon Photovoltaic Cells
There are three basic types of photovoltaic cells: mono-crystalline cells, polycrystalline cells, and amorphous cells. Crystalline silicon is the most common material for commercial applications. It has a well-known standard process because silicon is abundant. However, it requires expensive highly pure silicon and competes for silicon with electronics industry.
A mono-crystalline ceIn a PV cell that uses silicon as the semiconductor, the most common dopants are boron and phosphorous. Doping silicon with boron creates a material that can easily accept electrons (positive, p-type; the “absorber” layer) and doping silicon with phosphorous creates a material that can easily donate electrons (negative, n-type; the “emitter” layer). In a PV cell, the junction between p-type and n-type regions results in an electric field known as the cell’s positive/negative (P/N) junction. Photons of sunlight energy give electrons the push they need to hop onto the conductors (traces or grid lines) and into the electrical flow of the circuit. The P/N junction helps keep the electrons from simply recombining with an electron hole within the cell itself. The “pull” of the electrons toward the positive layer is what keeps the flow going: Give them a less resistive pathway to follow and they’ll gladly take it.ll is the most efficient, but also the most costly photovoltaic cell.
A polycrystalline cell is more common and less expensive, but also less efficient.
An amorphous cell is relatively inexpensive, but produces much less power. As such, the solar panels made from these photovoltaic cells must be larger to produce the same amount of energy. A UV-sensitive photo cell converts UV radiation to electrical energy.