Thienyl Self-Assembled Molecule Enabled Stable Perovskite/TOPCon Silicon Tandem

In mixed-component wide bandgap (WBG) perovskites, the elusive (111) crystal orientation confers enhanced operational stability compared to the conventional (100) orientation, yet typically compromises photovoltaic performance, presenting a critical stability-efficiency trade-off that remains unresolved. We report a thienyl-based self-assembled monolayer (SAM) as an additive in perovskite inks that templates preferential (111) perovskite crystallization. Besides, this SAM is found to spontaneously segregate at perovskite grain boundaries, where strong Pb-S bonding establishes a stable passivating interlayer while the conjugated thienyl moiety facilitates the regulation of energy band alignment. Implemented in perovskite/TOPCon tandem solar cells, this approach yields a champion power conversion efficiency of 33.00% (certified 32.56%). Crucially, the tandem devices demonstrate substantially improved operational stability, especially for photothermal stress, retaining > 89.8% of initial performance after 1000 h of continuous operation at 65°C under 1-sun illumination, validating the critical role of thienyl-based SAM in stabilizing perovskite-based tandem photovoltaics.