Impact of (NH4)2SO4 agricultural atmospheric pollutant on the degradation mechanisms of thin layer Cu(In,Ga)Se2 solar cells

Abstract

Chemical environment is usually disregarded in stability evaluations of photovoltaic devices but it can be critical for agrivoltaics (dual land use for energy production and agriculture). This work considers for the first time the effect of (NH₄)₂SO₄ agricultural pollutant on the chemical degradation mechanisms of thin layer solar cells. Cu(In,Ga)Se₂ (CIGS) cells with the architecture SLG/Mo/CIGS/Zn(O,S)/ZnMgO/Al:ZnO/NiAlNi and representative stacks were characterized at different times of temperature/humidity cyclic aging with and without (NH₄)₂SO₄. The pollutant strongly increased degradation rate and modified the key degradation mechanisms. Cu(In,Ga)Se₂-absorber and its interface with Mo-back contact were the most affected by accelerated aging without (NH₄)₂SO₄, while corrosion of front NiAlNi contacts and pitting of window Al-doped ZnO layer was the key degradation mechanism in the presence of (NH₄)₂SO₄. Chemical modifications of the cell and layers were coherent with optoelectrical characteristics loss. The work implies the necessity to take into account specific agricultural pollutants in reliability evaluation of new technologies for agrivoltaic applications.