Pyrite iron persulfide is an under-researched extremely promising semiconductor for use as the light-absorbing layer in thin-film photovoltaics (PV). University researchers have invented the first method to produce phase pure colloidal pyrite nanocrystals on a large scale for use in thin film solar cells. Pyrite nanocrystals (NCs) are of particular interest for low-cost solar energy conversion because of the prospect of fabricating inexpensive large-area modules by the roll-to-roll printing or spraying of NC “solar paint” onto flexible metal foils. Nanocrystal-based devices can achieve excellent manufacturing scalability at lower cost ($/Wp) than conventional single-crystal Si and existing thin film technologies. Furthermore university researchers have conceived of all the steps needed to manufacture an efficient low-cost p-n heterojunction solar cell from this pyrite paint. Nanocrystalline pyrite films are made by dip coating inkjet printing or doctor blading the paint/paste onto stainless foil. These films are sintered in special gas mixtures to yield stoichiometric polycrystalline pyrite films with carrier diffusion lengths that are significantly longer than the average optical absorption length. The surfaces of the films are then passivated chemically to increase the surface band gap and reduce the surface recombination velocity. The heterojunction partner is a window layer deposited by chemical bath deposition (CVD) or another method. The transparent top contact is made by sputtering CBD ALD or another method. Since this pyrite cell design mimics commercialized CdTe and CIGS technology this technology can be quickly incorporated into existing production lines. Applications: Terawatt level energy generation.
The great potential of pyrite lies in its superior scalability to terawatt (TW) levels of solar energy conversion than existing thin film technologies and its much lower cost than silicon.