Tin Oxide: The Next Benchmark Transport Material for Organic Solar Cells?

Organic solar cells (OSCs) are one of the most promising emerging photovoltaic technologies due to the rapid increase in efficiency in recent years. While efficiencies over 20% have been reported in laboratory scale devices using the conventional (p-i-n) structure, OSCs with inverted (n-i-p) structures still underperform, reaching values around 18%. Tin oxide (SnO) has recently emerged as a promising transport layer for OSCs. Yet, some reproducibility challenges shown by the literature have hindered the full adaptation of this electron transport layer (ETL) by the organic solar cell community. This Perspective evaluates the current status of investigation for SnO as the transport layer for OSCs, focusing on its integration into state-of-the-art systems and highlighting the challenges toward its implementation. We examine which strategies lead to the most efficient and stable devices using SnO and give a critical view of whether this material can soon become the next benchmark electron transport layer for OSCs.