Solar cells are large area p-n junctions. An N-type solar cell consists of a thin p-type silicon (doped with boron) layer over a much thicker n-type silicon (doped with phosphorus) layer. Electrical contacts are applied to both sides. The p-side is the front side facing the sun. It is given an antireflective coating, over which is pasted a clear adhesive (for instance EVA) which holds the front protective glass layer.Note: Do not be alarmed. This dope is legally recommended, not by doctors, but by engineers!
Why N-type solar cells are less common
Currently most of the crystalline solar cells are p-type. This is because of a lower cost of production of p-type. The reasons are probably attributable to history of development of solar cells. But performance wise, n-type solar cells can give much better efficiency compared to p-type solar cells. Two main factors account for this. Firstly, p-type material has boron (trivalent) doping. In the presence of light and oxygen boron undergoes some undesirable action, which reduces efficiency of conversion. This is called Light Induced Degradation or LID.