Analysis and characterization of iron pyrite nanocrystals and nanocrystalline thin films derived from bromide anion synthesis

We use a solution-based hot injection method to synthesize stable, phase pure and highly crystalline cubic iron pyrite (FeS₂) nanocrystals, with size varying from ∼70 to 150 nm. We use iron(ii) bromide as an iron precursor, elemental sulfur as the sulfur source, trioctylphosphine oxide (TOPO) and 1,2-hexanediol as capping ligands, and oleylamine (OLA) as a non-coordinating solvent during the synthesis. We report on the influence of hydrazine treatment, and of thermal sintering, on the morphological, electronic, optical, and surface chemical properties of FeS₂ films. Four point probe and Hall measurements indicate that these iron pyrite films are highly conductive. Although they are unsuitable as an effective photovoltaic light-absorbing layer, they offer clear potential as a conducting contact layer in photovoltaic and other optoelectronic devices.