Real-time transmission Mueller polarimetry on hydrogenated polymorphous silicon under current injection

We report on the use of an innovative optical characterization technique - real-time Mueller polarimetric imaging in transmission - for the characterization of thin-film silicon solar cells. In this work, we used this technique to monitor the evolution of optical retardance induced by the mechanical stresses in hydrogenated amorphous and polymorphous silicon (a-Si:H and pm-Si:H) p-i-n (PIN) solar cells. Under current injection of 200 mA cm-2, the retardance of the pm-Si:H PIN solar cells decreased, while that of the a-Si:H PIN solar cells showed no significant change. After the current injection, the pm-Si:H PIN solar cells showed dramatic macroscopic changes on a scale of tens of micrometres, such as local peel-off and delamination from the substrate. Our results demonstrate that current injection introduces local stress relaxation, which can be efficiently monitored prior to irreversible damage from a decrease in the retardance of the pm-Si:H PIN solar cells.