Exploring the device structure of next-gen Cu₂BaSn(S,Se)₄ solar cells

We are excited to share groundbreaking advancements in the realm of solar energy technology, particularly highlighting an emerging thinner-film solar cell: Cu₂BaSn(S,Se)₄. This innovative solar cell design has been capturing significant attention for its remarkable properties, but it has faced challenges in reaching the market due to a current power conversion efficiency (PCE) of just 6.17%.

The need for improved device structuring has been a critical factor holding back its commercialization. What could be done next? Waste materials and time experimenting? Not necessary anymore.

Our dedicated research group at the Autonomous University of Querétaro (UAQ) is actively exploring new strategies to enhance the performance of these emerging solar cells. Utilizing the SCAPS-1D simulation software from the University of Ghent, we recently published a comprehensive study in the Journal of Alloys and Compounds, focusing on optimizing the Cu₂BaSn(S,Se)₄ solar cell structure.

Our journey began by developing a baseline model that mirrors the experimental device structure: Al:ZnO/Mg:ZnO/Zn_1-xCd_xS/ZnS/Cu₂BaSn(S,Se)₄/Mo/glass. Achieving a theoretical PCE that aligns with experimental results was highly rewarding and validated our simulations.

We made strategic enhancements, such as incorporating an anti-reflection coating to minimize light loss, replacing molybdenum (Mo) with nickel (Ni) to facilitate ohmic contact, and adding a copper iodide (CuI) layer as a back surface field (BSF) to strengthen the electric field at the junction.

These modifications collectively improved the PCE from 6.17% to an impressive 10%. While this is a significant advancement, more work is needed to meet commercialization standards.

To further elevate the PCE, we focused on finding optimal transport layers for the solar cell. Our team meticulously simulated about 780 unique configurations utilizing various inorganic buffer and back surface field layers, including ZnSe, SnS₂, TiO₂, and more. By refining the thickness and carrier density of each layer, we achieved a remarkable PCE of 28% with the AZO/ZMO/TiO₂/Cu₂BaSn(S,Se)₄/CuI/Ni configuration, an outstanding result that showcases the potential of this technology.

One key area we focused on was the role of the BSF within the solar cell structure. Our in-depth analysis revealed that the BSF significantly influences the built-in potential, depletion width, and overall energy efficiency of the Cu₂BaSn(S,Se)₄ solar cell, highlighting its essential role in enhancing PCE.

In conclusion, our research significantly contributes to the photovoltaic community’s understanding of the Cu₂BaSn(S,Se)₄ solar cell’s design and optimization. We hope this work serves as a theoretical foundation for experimental scientists to explore potential advancements in this promising solar technology. Together, we are moving toward a new era of sustainable and high-performance solar solutions, propelling photovoltaics into a future where they can play a crucial role in our energy landscape.

This story is part of Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about Science X Dialog and how to participate.

Dr. Latha Marasamy is a Research Professor at the Faculty of Chemistry at UAQ, where she leads an innovative team of international students and researchers. Her diverse research interests encompass carbon and graphene, chalcogenide semiconductors, metal oxides, MOFs, as well as plasmonic metal nitrides and phosphides, all aimed at energy and environmental applications. Additionally, her team provides theoretical insights into solar cells through the use of SCAPS-1D simulation.