Cadmium telluride
A semiconductor that absorbs sunlight in a layer a few microns thick — the only thin-film solar technology to have taken serious market share from silicon.
Cadmium telluride absorbs sunlight about a hundred times more strongly than silicon does, which means a working solar cell can be a few microns thick rather than a couple of hundred. Less material, less energy to make, and a panel that can be deposited onto glass in a continuous process rather than assembled from sawn wafers.
Its band gap of roughly 1.5 electronvolts is also close to the theoretical best for a single-junction cell under sunlight, which is a piece of luck rather than a design.
Economic significance
It is the only thin-film photovoltaic technology to have taken and held a meaningful share of a market that silicon otherwise dominates, and it performs relatively better in heat and in diffuse light — which matters more in the field than peak efficiency does.
The constraint is tellurium. It is one of the rarest stable elements in the crust, has no ore body of its own, and reaches the market only as a by-product of copper refining — so the technology's ceiling is set by how much copper the world refines rather than by anything about solar demand.
The cadmium is a persistent public objection and a manageable industrial one. The compound is far more stable and far less bioavailable than the metal, panels are sealed in glass, and the manufacturers run take-back recycling — but a technology that puts a cumulative poison on millions of roofs has to keep making that argument.
How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.
How this connects
Where a connection has been confirmed by an outside reference, that reference is named beside it.
contains
- Cadmium — element · half the atoms — and the persistent public objection to the technology, though the compound is far more stable and less bioavailable than the metal Wikidata
- Tellurium — element · the other half, and the technology's real ceiling: tellurium has no ore body and arrives only as a by-product of copper refining Wikidata
is used as
- Photovoltaics — application · the only thin-film technology to have taken and held real market share from silicon
is produced by
- Vapour deposition — process · deposited straight onto glass in a continuous line — the reason a thin-film panel is cheaper to make than a silicon one is that it is never a wafer
is used in
- Energy generation — industry · thin-film photovoltaics, the principal commercial alternative to crystalline silicon
is an alternative to
- Polysilicon — material · the thin-film alternative in photovoltaics: far less material and far less energy per panel, at a lower efficiency and with cadmium and tellurium to account for — it holds a steady minority share rather than losing
Sources
- Material WorldOur own writing
- Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)