Enhanced Photovoltaic Performance of Inverted Perovskite Solar Cells Employing a Cerium Oxide Passivation Layer

Metal halide perovskite solar cells (PSCs) have achieved a power conversion efficiency (PCE) of 26.7%, establishing them as strong candidates for next-generation solar cell technology owing to their unique optoelectronic properties and solution processability. However, defects at grain boundaries and interfaces within the perovskite layer limit both stability and performance. Therefore, this study aims to mitigate these challenges by introducing a thin layer of amorphous cerium oxide (CeO_x) as an inorganic passivation layer, offering advantages over conventional organic passivation layers. A thin amorphous CeO_x passivation layer enhances the built-in electric field in the perovskite, improving charge transfer without the increased resistance of thick layers generally used as electron transport layers (ETLs). This approach yielded an inverted PSC with a PCE of 19.30%, securing high performance with photostability. This result highlights the potential of thin CeO_x passivation to enhance the efficiency and stability of PSCs.