Bifacial Chalcogenide Thin-Film Solar Cells: Concepts, Challenges, and Opportunities

Abstract

Bifacial solar cells effectively increase photovoltaic energy generation by harnessing light from both the front and rear surfaces. In the realm of thin-film technology, inorganic chalcogenides specifically (Cu (In, Ga)Se2, S), CdTe, Cu2ZnSn (S, Se)4, and Sb2(S, Se)3 exhibit significant potential owing to their adjustable band gaps, robust absorption characteristics, and scalable manufacturing processes. This review emphasizes current advancements in chalcogenide-based bifacial photovoltaics, concentrating on device principles, absorber appropriateness, and performance limitations. Numerical and experimental investigations demonstrate that bifacial illumination not only alleviates interfacial band bending under specific conditions but also produces power outputs that surpass the cumulative contributions of single-side illumination, while exhibiting resilience to diffuse rear illumination. Nevertheless, actual albedo levels indicate that reductions in front-side efficiency cannot be entirely compensated for rear-side improvements, highlighting the necessity for clear low-recombination contacts, efficient light management, and robust device interfaces. We end with an overview of strategies spanning back contact engineering to outdoor durability that are crucial for advancing bifacial chalcogenide photovoltaics from laboratory demonstrations to initial commercialization. Bifacial solar cell configurations are particularly advantageous for tandem applications. This offers a promising pathway to further enhance overall device efficiency.