Doping Cu(In,Ga)Se2 (CIGS) thin films with Sb can provide large grains at lower processing temperatures than are normally required. In this study, we incorporated Sb into the precursor of a two-step selenization process. We saw enhanced grain size and improved device performance compared to similarly processed CIGS films made without Sb. The optoelectronic properties of the Sb-doped CIGS films were examined with photoluminescence (PL) and admittance spectroscopy. These techniques allowed us to evaluate the origin of a lower-energy PL peak that is not typically seen in CIGS.