Local mechanical and electrical behavior in CdTe thin film solar cells revealed by scanning probe microscopy

The nanoscale electrical and mechanical properties in the CdTe thin films solar cells were investigated using the scanning probe microscopy. The comparative localized electrical and mechanical properties between as-grown and CdCl2 treated CdTe thin films for the grain and grain boundaries were studied using the conductive atomic force microscopy (cAFM) and force modulation microscopy (FMM). An increased electrical behavior and decreased elastic stiffness in the CdCl2 treated thin films were recorded to elucidate the impact from the grain growth of CdTe grains. On applying a simulated working electrical bias into the CdTe thin-film solar cells, the electric field across the CdTe film can increase the softness of CdTe thin film. The results imply the presence of a potential mechanical failure site in the CdTe grain boundary, which may lead to device degradation.