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 V_MP, and a fixed current injection near I_MP. The EL intensity was integrated across the image to give quantitative values EL_V and EL_I, respectively. Differences in EL_V between different modules reflect differences in average neutral bulk electronic properties (parameterized by carrier diffusion length L_D), while EL_I is related to both neutral bulk and Space Charge Region (SCR) collection (dependent on both L_D 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.