PV Gap

Janet Said:

Photovoltaic cell question?

We Answered:

Actually p-type is the side more number of holes and thus has a tendency to accept electrons, and similarly the n-type has more electrons so tends to accept holes.
So the p-type layer is not negative. I think you are referring to the case of a p-n junction diode. The p-type layer has a tendency to accept electrons and the n-type repels electrons(as its high on electrons) so the electron travels from outer circuit to the p-side. The reason why electron goes from the outer circuit and not directly is because in between the 2 layers an immobile non conducting layer is present.
And as per the question of why the electron moves to n-type in the first place is that, we create a deficiency of holes and not excess of electrons. The n-type is usually produced by adding a pentavalent atom(like phosphorous) to tetravalent atom(like Silicon). This cause bonding of 4 electron-hole pairs and leaves 1 electron free and hence the n-type nature.
Similarly for p-type we use a trivalent atom which leaves 1 hole free.
So we never introduce extra electrons instead they are made free.