COMSOL simulation of non-radiative recombination heat and joule heat in CZTSSe thin film solar cells

Abstract

A detailed coupled simulation model has been developed to analyze the impact of defect, voltage, and temperature on heat generation rate in CZTSSe thin film solar cells. This has been simulated by mapping the non-radiative recombination heat and Joule heat due to increased defect and voltage across the bulk of this solar cell. Both non-radiative recombination heat and Joule heat depend on defect density and voltage. The non-radiative recombination in solar cells includes the Auger recombination and the Shockley-Read-Hall (SRH) recombination due to mid-gap defects. Increasing the defect density from 1012 cm−3 to 1018 cm−3 increased the heat generation from 105 W/m3 to 109 W/m3. Also, voltage is an effective parameter in heat generation in solar cells. Increasing the voltage from 0 to 0.6 V (near the open-circuit voltage of the cell) has flattened out the profile of non-radiative recombination heat across the cell and the spike of heat generation at the junction has significantly reduced. In any case, the heat generation (due to defect or voltage increment) shows a maximum peak at CZTSSe/CdS junction and a smaller increase at (Mo(S,Se)2/CZTSSe) interface. Finally, the non-radiative recombination heat was calculated at both room temperature (initial run) and at secondary temperature distribution (coupled run).