In-depth photoluminescence spectra of pure CIGS thin films.

Photoluminescence spectra of pure CIGS thin films with different Ga in-depth gradients are systematically investigated. Pure Na-free films are prepared with an innovative hybrid deposition technique, whose optical luminescence emission is analyzed as a function of the depth and is correlated to the radiative intrinsic defects of the material. Finally, the highlighted features are correlated with the performances of test solar cells prepared with the same growths.