Enhancing Interfacial Contact in Perovskite/Silicon Tandem Solar Cells Through TaO _X Passivation

Perovskite/silicon tandem solar cells demonstrating tremendous potential for commercialization that position them as a transformative technology in photovoltaics. However, the poor interface contact between perovskite and C₆₀ has long been a critical factor limiting the power conversion efficiency (PCE) of top perovskite solar cells. Here, a multifunctional inorganic tantalum oxide (TaO_X) film as a passivation layer is introduced, which not only suppresses recombination across the interface but also improves energy level alignment and enhances charge extraction at the perovskite/C₆₀ interface. More importantly, TaO_X demonstrates exceptional thermal stability, which significantly enhances the overall stability of the device. These synergistic effects enable the fabrication of a single-junction cell with a PCE of 21.0% at a bandgap of 1.68 eV. Furthermore, when combined with a double-sided tunnel oxide passivated contact silicon bottom cell, a tandem cell with a PCE of 29.5% at 1 cm² is achieved. Furthermore, the unencapsulated TaO_X-based devices exhibited significantly improved stability when subjected to ISOS-L-1 accelerated aging conditions.