Towards Fool’s Gold Solar Cells: Rietveld Refinement of Mackinawite-like Iron Sulfide Nanocrystals in Pyrite Synthesis for Identification of Phase Evolution

Iron pyrite (FeS₂) is a contender for next-generation photovoltaic materials, but requires band gap engineering to be useful. To engineer the band gap, iron sulfide nanocrystal synthesis must be well understood and controllable. This thesis investigates the phase evolutions of iron sulfide nanocrystals under high and low temperature hot-injection synthetic conditions by analyzing crystal structure from Rietveld refinements on powder X-ray diffraction. Under low temperature conditions, a monolayer of mackinawite-like FeS was generated and under high temperatures, a distorted mackinawite-like structure first crystallized and continuously evolved into pyrite.