Correlating multiple spatially-resolved techniques (LBIC/Raman/PL/Reflectance/SEM/AFM) in the study of microscopic inhomogeneity of thin-film solar cells: Cu2ZnSnSe4 as an example

An array of correlated spatially-resolved techniques, including μ-LBIC/Raman/PL/Reflectance in conjunction with SEM and AFM were applied to study the spatial inhomogeneity in the optical and electrical properties of a CZTSe thin film solar cell. Together these tools allow us to identify the origin of the imperfections and their impacts on device performance. We find that in μ-LBIC mapping the external quantum efficiency (EQE) and its variation with illumination density depend sensitively on the CdS thickness. The thicker CdS region is found to exhibit much less EQE reduction or droop at high illumination level, indicating that the CZTSe/CdS interfacial property is sensitive to the CdS layer thickness.