Electroluminescence intensity analysis of neutral bulk and space charge region collection effects on large-area CIGS module performance

We perform electroluminescence (EL) intensity analysis on large-area monolithically-integrated Cu(In,Ga)Se2 (CIGS) modules. EL was measured in two modes: a fixed voltage near VMP, and a fixed current injection near IMP. The EL intensity was integrated across the image to give quantitative values ELV and ELI, respectively. Differences in ELV between different modules reflect differences in average neutral bulk electronic properties (parameterized by carrier diffusion length LD), while ELI is related to both neutral bulk and Space Charge Region (SCR) collection (dependent on both LD and non-radiative recombination lifetime parameter τ). Significant differences in EL intensity are observed between modules made with different precursor structures. By conducting large-area EL intensity analysis, we have demonstrated a method for decoupling and comparing neutral bulk and SCR collection properties of the absorbers in large-area monolithically integrated CIGS modules.