Two-terminal tandem solar cell with Sb2S3/Sb2Se3 absorber pair: achieving 14% power conversion efficiency

Abstract

Embarking on a journey toward high solar efficiency, this study delves into a two-terminal tandem solar cell (TSC) featuring Sb2S3/Sb2Se3 as an absorber layer. The tandem setup consists of different bandgap (Eg) absorbers to selectively target photon energies: the top cell employs a wide bandgap material to efficiently absorb high-energy photons, while the bottom cell utilizes a lower bandgap material to capture refined photons transmitted from the top cell. This strategy mitigates thermalization and transparent energy losses by assigning distinct photon absorption and conversion roles to the top and bottom cells. Realizing peak efficiency in a tandem configuration rests on the apt choice of active materials for the top and bottom cells. In this regard, a comprehensive study is presented, introducing a TSC architecture that pairs an Sb2S3-based top cell (Eg 1.7 eV) with a Sb2Se3-based bottom cell (Eg 1.2 eV). Through meticulous analysis, the performance of these cells in the tandem setup is analyzed, employing methods such as filtered spectrum analysis and current-matching strategies. The Sb2S3/Sb2Se3 tandem design incorporates a critical tunnel recombination junction facilitated by an ITO layer. Noteworthy is the investigation’s uncovering of impressive metrics for the tandem device, encompassing an open-circuit voltage (VOC) of 1.58 V, a current density (JSC) of 15.50 mA.cm−2, and a fill factor (FF) of 56.90%. This collective attainment culminates in an extraordinary power conversion efficiency of 14%. The insights gleaned from this study hold substantial promise for the future development of monolithic TSC. By adroitly harnessing the distinctive strengths of Sb2S3 and Sb2Se3 materials within a tandem configuration, a clear trajectory is charted toward momentous advancement in solar energy conversion technology.