Improved modeling of the effect of sulfur on optical and electrical properties in a calibrated simulation model of a CIGSSe solar module

Abstract

A 1D single-cell simulation model for a laminated Ga-rich cm2 n-ZnO/ZnOS/Cu(In,Ga)(S,Se)2/Mo(Se,S)2-based solar module with a power conversion efficiency of close to 19% is developed and calibrated on its current–voltage (IV), capacitance–voltage (CV), external quantum efficiency(EQE) and measurement data. A careful discussion of the simulation parameters is presented, from which three main results are found: (a) a discrepancy between the band gaps calculated from glow discharge optical emission spectroscopy (GDOES) and EQE measurement data is ascribed to the segregation behavior of sulfur in the Cu(In,Ga)(S,Se)2 crystal and can be solved by a modification of the sulfur GDOES profile in accordance with grain sizes, (b) the saturation current density and the diode factor can be calibrated by electron and hole capture cross-sections of the absorber to match the measured IV data, and (c) a modification of the illumination spectrum corresponding to reflection losses can account for missing real part values of the complex refractive index. The resulting interplay of recombination mechanisms in the simulation model is then verified by a generation-dependent V oc measurement.