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

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 (NH 4 ) 2 SO 4 agricultural pollutant on the chemical degradation mechanisms of thin layer solar cells. Cu(In,Ga)Se 2 (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 (NH 4 ) 2 SO 4 . The pollutant strongly increased degradation rate and modified the key degradation mechanisms. Cu(In,Ga)Se 2 -absorber and its interface with Mo-back contact were the most affected by accelerated aging without (NH 4 ) 2 SO 4 , while corrosion of front NiAlNi contacts and pitting of window Al-doped ZnO layer was the key degradation mechanism in the presence of (NH 4 ) 2 SO 4 . 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. • T°C/humidity stability of CIGS solar cell was compromised by (NH 4 ) 2 SO 4 fertilizer. • Different degradation mechanisms occurred during ageing with and without (NH 4 ) 2 SO 4 . • The pollutant affected Na and Mo redistribution at the Mo/CIGS interface and in CIGS. • In presence of (NH 4 ) 2 SO 4 contact’s corrosion led to irreversible conductivity loss. • Pitting corrosion of Al-doped ZnO transparent conductive oxide led to optical losses.