Solar power is projected to become the largest single global source of electricity generation by 2050, with photovoltaic devices constituting the majority of this market share . Next generation materials based on material systems with direct band gaps fabricated in thin films are predicted to make considerable contributions to this market with the promise of significantly reducing materials costs and solar cell bulk. At present, one of the most promising thin film absorber material is CuInxGa(1-x)Se2 (CIGS), which has been shown to achieve a solar conversion efficiency in the laboratory of 21.7% . However, the high cost of the raw materials in this system has driven research to find more cost effective alternatives .
One such alternative material system based on the crystallographic kesterite family Cu2ZnSn(S,Se)4 promises to be highly cost competitive due to the use of earth abundant elements. However, this system is currently less mature than CIGS with a record solar conversion efficiencies of 12.6%  or 11.6%  if no sulphur is used. The challenges impeding improvement are related to chemical and nanoscale structural inhomogenities that lead to a reduction in the open circuit voltage of the system . A full understanding of these defects and, hence, progression in fabrication of these materials thus requires a characterization technique capable of spatially mapping out compositional, structural, and electronic trends with nanoscale spatial resolution.
In this contribution, we present our progress towards the development of a methodology that will allow researchers to directly address these challenges with nanometer spatial resolution over micron sized areas of sample. We accomplish this through two stages. First, a sample preparation methodology enabling a very large field of view while retaining a reasonable lamellae thickness utilizing the Focused Ion Beam is presented. Preliminary results of this methodology are presented in figure 1, revealing a field of view of many microns over a sample that is under 80 nm thick in the absorber layer. Second, we employ correlative EDX and EELS spectroscopic imaging techniques over large areas, focusing on features such as grain boundaries and pores. The simultaneous use of both spectroscopy techniques allows for two independent quantitative assessments of composition, reducing systematic errors. It also assists in the identification and elimination of artifacts that may arise through the data treatment. The result is large area maps with optimized uncertainties from a materials system containing many difficult and overlapping spectroscopy edges. These techniques are then applied to state-of-the-art samples with very high efficiencies .
 International Energy Agency: Technology Roadmap: Solar Photovoltaic Energy. 2014.
 Jackson, P. et al.: Properties of Cu(In,Ga)Se2 solar cells with new record efficiencies up to 21.7%. Phys. Status Solidi RRL 9 (2015) 28.
 European Comission: Report on critical raw materials for the EU. 2014.
 Wang, W. et al.: Device Characteristics of CZTSSe Thin-Film Solar Cells with 12.6% Efficiency. Adv. Energy Mater. 4 (2014) 1301465.
 Lee, Y.S. et al.: Cu2ZnSnSe4 Thin-Film Solar Cells by Thermal Co-evaporation with 11.6% Efficiency and Improved Minority Carrier Diffusion Length. Adv. Energy Mater. 5 (2015) 1401372.
 Mitzi, D.B. et al.: Prospects and performance limitations for Cu–Zn–Sn–S–Se photovoltaic technology. Phil. T. Roy. Soc. A 371 (2013) 20110432.
 Giraldo, S. et al.: Large Efficiency Improvement in Cu2ZnSnSe4 Solar Cells by Introducing a Superficial Ge Nanolayer. Adv. Energy Mater. (2015) 1501070.
 Hubert, M. et al.: ROBPCA: A New Approach to Robust Principal Component Analysis. Technometrics 47 (2005) 64.
To cite this abstract:Thomas Thersleff, Sergio Giraldo, Haibing Xie, Paul Pistor, Edgardo Saucedo, Klaus Leifer; Quantitative compositional mapping on the nanoscale over large fields of view in thin film solar cells from earth abundant elements. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/quantitative-compositional-mapping-on-the-nanoscale-over-large-fields-of-view-in-thin-film-solar-cells-from-earth-abundant-elements/. Accessed: January 21, 2022
EMC Abstracts - https://emc-proceedings.com/abstract/quantitative-compositional-mapping-on-the-nanoscale-over-large-fields-of-view-in-thin-film-solar-cells-from-earth-abundant-elements/