Paper TF+AS-WeA1
Studying the Microstructure of Cu2ZnSn(S,Se)4 Thin Film Solar Cells

Wednesday, October 31, 2012, 2:00 pm, Room 11

To advance the next generation photovoltaic technology, the new ink-based Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have attracted rapid growth attention in the thin film photovoltaic areas. As a potential alternative to CIGS, the CZTSSe technology offers a non-vacuum based and likely low manufacturing cost process with active area efficiency above 9%. In particular, the fact that CZTSSe utilizes only earth abundant elements enables the sustainability & renewability for future green energy demand.

The overall CZTSSe solar cell developed by DuPont scientists consists of multi-layer inorganic structures of ITO/ ZnO/ CdS / CZT(S,Se) / Mo on sodalime glass substrate. A novel synthetic method has been developed to produce the active CZTSSe layer. During the process, binary and ternary chalcogenide nanoparticles are first synthesized as starting materials, formulated into a precursor ink, applied onto a substrate, and then converted into CZTSSe upon a thermal annealing process. To aid product development for optimum efficiency, chemical and structural characterization of the active CZTSSe layer and interfaces between different layers are performed using multiple analytical techniques. For example, sputter depth profiling with XPS and Auger, and cross-section SEM/EDX helped us to visualize the structural chemistry at specific locations in the films which enabled the team to adjust ink formation as well as processing conditions for better and more efficient cell production. This presentation will cover the characterization of CZTSSe solar cells, including the study of film composition and morphology, inter-layer diffusion, and their correlation with device performance.