Cadmium Telluride (CdTe) is the material of choice for making thin film solar cells.

Thin film solar cells are only 1/10 the thickness of a human hair, and this allows the cells to be lightweight and flexible. One advantage of this is that they can be integrated directly into roofing material.

So what is Cadmium Telluride? CdTe is a crystalline compound made from Cadmium and Tellurium. Unlike silicon, CdTe does not have widespread commercial uses.

Cadmium Telluride Material
Cadmium Telluride Material

Why is CdTe the material of choice for making thin film solar cells? Here are a few reasons:

  • CdTe has a band gap of 1.45 eV (close to the optimal value of 1.34 eV)
  • The material possesses long term stability of roughly 20 years. While the stability is good enough for most consumers, it is not quite as stable as silicon

Here is what a typical Cadmium Telluride solar cell looks like.

CdTe-Solar-Cell-Diagram
Cadmium Telluride Solar Cell Composition / Image Credit: www.nrel.gov

One concern with CdTe solar cells is the toxicity of Cadmium. The toxicity concern is currently mitigated by recycling the CdTe modules at the end of their life. Current recycling programs can recover up to 95% of the CdTe and 90% of the glass.

If this solar cell technology continues to grow, the usage of rare materials may become a limiting factor. Tellerium is an element that is almost as rare as platinum.