@Article{cl.2026.077226,
AUTHOR = {Jun Zhang, Jiayi Song, Wangjian Fu, Jiren Yuan},
TITLE = {Numerical Simulation of High-Performance Lead-Free BaZrS<sub>3</sub>/CIGS Tandem Solar Cells},
JOURNAL = {Chalcogenide Letters},
VOLUME = {23},
YEAR = {2026},
NUMBER = {2},
PAGES = {--},
URL = {http://www.techscience.com/CL/v23n2/66462},
ISSN = {1584-8663},
ABSTRACT = {Tandem solar cells employing lead-free perovskite materials offer a compelling pathway to simultaneously achieve high power conversion efficiency (PCE) and improved environmental sustainability. In this work, we present a comprehensive numerical simulation study of monolithic and mechanically stacked tandem solar cells based on the chalcogenide perovskite BaZrS<sub>3</sub> as the top subcell and Cu(In,Ga)Se<sub>2</sub> (CIGS) as the bottom subcell. For the four-terminal (4-T) configuration, a systematic optimization workflow was implemented, encompassing the thickness of absorber and carrier-transport layers, doping concentrations, and the introduction of a LiF anti-reflection coating. This approach led to a marked reduction in parasitic absorption and reflection losses, ultimately yielding a champion PCE of 34.7%. In the two-terminal (2-T) series-connected tandem, current matching was achieved by tuning the Ga content in the CIGS bottom absorber, which adjusts its bandgap and spectral response. Further co-optimization of doping profiles in the transport layers and the CIGS absorber resulted in a maximum PCE of 32.65%. Our analysis also highlights that the defect density within the BaZrS<sub>3</sub> layer is a critical performance governor; increasing trap densities severely degrade open-circuit voltage and fill factor, underscoring the importance of high-quality perovskite film synthesis. The results demonstrate the considerable potential of the eco-friendly BaZrS<sub>3</sub>/CIGS tandem architecture for next-generation photovoltaics.},
DOI = {10.32604/cl.2026.077226}
}