Youre "structure " of a PV cell, hasnt used tellurides and/ or indium compounds for like 35 years . We use Phosphorus or Arsenic (they are both, along with Selenium , very similar acting in a crystal)as Doping agents for the P material and Boron for the N(ALSO, the structure of the P and N materials incorporate the above elements into the silica tertahedra itself, the elemenst dont lay around on the surface to get leaxhed out. (we call em defect lattices) Thats where many noble metals come from. DEFECT LATTICES contain a few percent of the "doping" element incorporated into the crystal. (That is why LEAD crystal is a polyscrystalline silica (Silane/trydimite) with lead at about 5 to 6 % lead qnd is safe to store any kinds of food or acid drinks. The lead does not leach because its incorporated within a silica crystal structure and is "Locked" inplace never to move,neither does any element doped into the glass "P" and "N" material.[For information purposes, the USDOE has looked at "melting spent U with trydimite to create great crystallattices to contain and dispose Uranium from nuke plants). It will emit radiation but will NOT chemically leach.
The N material (in todays world)is almost always boron.
This is the way almost PV cells are cast in 2010 They dont need any rare eartjhs anymore, thats why PV cells have come down in price precipitously in the last 30 years. (Sometimes more complex isnt better)
PS polycryastalline silica and microcrystalline silica ARE REALLY NOT glass, they are an actual crystalline tetrahedron of SiO2- and SiOh. Glass is an amorphous compound (its actually a liquidus).
The layers of a PV cell are as follows:
Solar Cell Structure:
A. Encapsulate - The encapsulate, made of glass or other clear material such clear plastic, seals the cell from the external environment.
B. Contact Grid- The contact grid is made of a good conductor, such as a metal, and it serves as a collector of electrons.
C. The Antireflective Coating (AR Coating)- Through a combination of a favorable refractive index, and thickness, this layer serves to guide light into the solar cell. Without this layer, much of the light would simply bounce off the surface.
D. N-Type Silicon - N-type silicon is created by doping (contaminating) the Si with compounds that contain one more valence electrons* than Si does, such as with either Phosphorus or Arsenic. Since only four electrons are required to bond with the four adjacent silicon atoms, the fifth valence electron is available for conduction.
E. P-Type Silicon- P-type silicon is created by doping with compounds containing one less valence electrons* than Si does, such as with Boron. When silicon (four valence electrons) is doped with atoms that have one less valence electrons (three valence electrons), only three electrons are available for bonding with four adjacent silicon atoms, therefore an incomplete bond (hole) exists which can attract an electron from a nearby atom. Filling one hole creates another hole in a different Si atom. This movement of holes is available for conduction.
F. Back Contact - The back contact, made out of a metal, covers the entire back surface of the solar cell and acts as a conductor.