5.15.3 Availability of raw materials
Large-scale manufacture of some types of photovoltaic cells could use significant fractions of the world supply of some raw materials. The principal elements in question are indium and, to a lesser extent, tellurium.
Thin film technologies are potentially affected by limited supplies of indium and similar elements because of the use of indium tin oxide for the transparent front contact layer. Whether lack of indium resources becomes a limiting problem depends on the price of these elements on the world market. A clever conservation approach is to recycle modules at the end of their life by etching off the active material, leaving the indium tin oxide intact ready for reuse with a fresh film of semiconductor. Even so, there are now many research groups around the world looking for alternative transparent conductors, such as for example fluorine-doped tin oxide.