11 November 2025
Selenium: the light-sensitive copper by-product used in solar and defence
Key insights from this briefing
Why is selenium useful in light-sensitive and photovoltaic technologies?
Selenium is a semiconductor whose electrical behaviour changes when it absorbs light. Its photoconductive properties enabled early light meters, while selenium-containing compounds such as CIGS can convert incoming photons into electrical power for thin-film solar cells and optical sensing.
Why does selenium purification capacity matter as much as copper production?
Most selenium is recovered from anode slimes produced during electrolytic copper refining, but high-purity selenium still requires specialised recovery and purification. Refining capacity is concentrated in a small number of countries, so supply can tighten even when copper feedstock is available if recovery rates or purification capacity are constrained.
Excerpt from this briefing's Industry Insight
Selenium's strategic value comes from its semiconductor and photoelectric behaviour. It can change conductivity when exposed to light and, in compounds such as CIGS, can convert light into electricity, supporting solar, sensing and defence applications. Yet selenium has almost no primary mining industry: it is recovered mainly from anode slimes generated during copper refining. Supply is therefore tied to copper-smelter activity and specialised purification capacity, making high-purity selenium vulnerable to disruptions that have little to do with its own market price.
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