Abstract/Summary

Bismuth-containing chalcohalides are currently under consideration for photovoltaic applications and easily-scalable synthetic routes for these materials are needed. The work presented here demonstrates the feasibility of synthesising large quantities of phase-pure chalcohalides by ball milling. This avoids deviations from stoichiometry due to the volatilisation of halides that can occur during high-temperature synthesis. Bulk polycrystalline samples of BiQI (Q = S, Se) were produced by ball milling and characterised by powder X-ray diffraction, UV-vis diffuse reflectance and thermogravimetric analysis. Rietveld refinements confirm that phase-pure BiSI and BiSeI were produced. These materials were found to be thermally stable up to 270 - 330 °C, and to exhibit optical band gaps of 1.56 and 1.26 eV for BiSI and BiSeI respectively. Preliminary results on the preparation of films by spin-coating slurries of the ball milled powders are also presented.