PV Gap

Elmer Said:

Would someone like to give me their two sense of this chemistry problem?

We Answered:

the actual equation is 2 Mg(s) + SiCl4(l)---> 2 MgCl2 + Si(s)

a) There are 4 electrons per atom of pure silicon because silicon is coing from a Si4+ charge to an Si with a neutral charge. Therefore 4 electrons are transferred.

b) the product of pure silicon is a reduction reaction. This is because Silicon is gaining electrons and reduction is the gain of electrions (an easy way to remember that is OIL RIG = Oxidation is loss, reduction is gain)

P.S. it's give your two "cents" not sense

Karl Said:

consider ideal solar cells made of Ge, Si, and GaAs with Voc of 0.35V, 0.65V, and 1.05V. calculate FF?

We Answered:

The Fill Factor is related to the squareness of the IV curve. The link below says it all, with diagrams, formula etc far better than I could.

Erin Said:

why a Si solar cell would not work without a p-n junction?

We Answered:

Because you need the built-in electric field created by the depletion region to sweep and separate the photo-generated excess electron-hole pairs to the opposite sides of the device, this is essentially what "pushes" the current that drives the load attached to the cell. The imbalance of e-h pairs due to the absorbed light is what creates the EMF.

If you only have either a p only or an n material only, you generate electron-hole pairs alright, but there is no build in electric field to separate them; what you would get is a plain photoconductor (a light sensitive resistor) which will not generate emf.