Infrared reflection−absorption spectroscopy (IRRAS) was used to investigate a thin alkane-thiol overlayer on pyrite, and the experimental IRRAS results were compared to calculated spectra. The work was motivated by the importance of understanding the surface chemistry of pyrite single crystals because surface chemistry has previously been linked to solar-to-electrical energy conversion efficiency through both computational and experimental efforts. Angle-dependent IRRAS studies together with computational efforts showed a dependence of absorption strength on the angle of the incident light and showed that the combination of angle-dependent studies and computational efforts are a powerful tool for studying thin overlayers on pyrite.

Pyrite (FeS2) has recently attracted significant interest as a photovoltaic material due to its promising optical properties, high photon to electron conversion yield, and lowcost raw materials. However, hopes have been tempered by recent discoveries that suggest the presence of hard to remove bulk sulfur defects. This research was focused on engineering and implementing the crystallization of pyrite from a sulfur rich solution to counteract the material's natural tendency to form bulk sulfur defects. Homoeptiaxial layers and single-crystal samples have been grown from tellurium sulfur melts with an Fe:S ratio of 1:4 using both natural and synthetic substrates. The homoepitaxial layer has been characterized using scanning electron microscopy (SEM), transmission electron v