Ultrafast Dynamics of Complete Sb2S3 Solar Cells Unveiled via a Bifacial Architecture

Charge transfer and recombination dynamics are key to understanding and optimizing photovoltaic devices. However, metallic contacts are typically used to fabricate devices, making them incompatible with transmission spectroscopic techniques such as transient absorption spectroscopy (TAS). Omission of the top contact to avoid this issue results in mismatched results and has limited previous work examining the dynamics in thin-film Sb₂S₃-based devices. In this work, this challenge is overcome by developing a new methodology, adding a protective layer of ZnO over hole transport materials, allowing fabrication of transparent (i.e., bifacial) solar cell devices. Photovoltaic characterization reveals similar J-V curves between reference and bifacial cells. Examination with TAS reveals a modified mechanism that builds off of previously proposed models for similar systems. Optical modeling supports the understanding of several important changes to the mechanism. These results provide a path toward the investigation of photo-driven dynamics under more realistic operating conditions.