A new paper in the journal Environmental Science & Technology assesses the requirements for scaling solar photovoltaic systems to the terawatt levels needed to supply electric power on a global scale. The authors identify iron pyrite, FeS2, as an attractive but unconventional alternative: The raw materials for pyrite aren’t scarce, and both the energy and monetary costs of production could be low.
In addition to having an outstanding Klm value, pyrite is a strongly light-absorbing semiconductor with a band gap in the right range for use in composite materials systems for photovoltaics. This provides ample reason to study and learn to control pyrite growth processes at the atomistic level.
Biological examples show that protein molecules can guide crystal growth by selectively binding to crystal surfaces and surface features, and pyrite can grow under conditions that are compatible not just with proteins, but with living organisms. Development of a good crystal-shaping molecular toolkit could provide a route to a useful class of atomically precise fabrication techniques, and pyrite is an attractive target.
Pyrite may be relatively new as a serious candidate for photovoltaic applications, but pyrite basking in sunlight is a very old phenomenon, older than Earth itself. Pyrite crystals were an ingredient of the solar nebula from which Earth formed.