Copper zinc tin sulfide (CZTS) is a quaternary semiconducting compound with kesterite structure, which has received increasing interest for applications in solar cells. The class of related materials includes other I-II-IV-VI such as copper zinc tin selenide (CZTSe) and the sulfur-selenium alloy CZTSSe. CZTS offers properties similar to CIGS making it well suited for use as a thin-film solar cell, but unlike CIGS (or CdTe), CZTS is composed of only abundant and non-toxic elements. Solar cell efficiencies above 10% have recently been demonstrated.