The Bocarsly Group works with the Cava Group on a class of p-type semiconductors with a chalcopyrite, tetragonal crystal structure; namely, copper-indium-gallium dichalcogenides (diselenides or disulfides) [Cu(In,Ga)(S,Se)2], abbreviated as CIGS. This direct bandgap semiconductor is attractive for photoelectrochemical (PEC) processes due to its high optical absorption coefficient, tunable bandgap (ranging from 1.0–2.4 eV), and appropriate conduction band edges positioned more negative than the thermodynamic redox potentials of most CO2 reduction products and hydrogen evolution.
Current work on CIGS includes: (1) fundamental studies on the crystallographic orientation of the exposed photocathode surface and (2) synthesis and PEC analysis of new CIGS materials by substitution or addition of elements in the ABX2 chalcopyrite structure.
