The interfacial molecular dipole enhances the photovoltaic performance of perovskite solar cells (PSCs) by facilitating improved charge extraction. However, conventional self-assembled monolayers (SAMs) face challenges like inadequate interface coverage and weak dipole interactions. Herein, we develop a strategy using a self-assembled ferroelectric layer to modify the interfacial properties of PSCs. Specifically, we employ 1-adamantanamine hydroiodide (ADAI) to establish robust chemical interactions and create a dipole layer over the perovskite. The oriented molecular packing and spontaneous polarity of ferroelectric ADAI generate a substantial interfacial dipole, adjusting band bending at the anode, reducing band misalignment, and suppressing charge recombination. Consequently, our formamidinium lead iodide-based conventional PSC achieves efficiencies of 25.13% (0.06 cm²) and 23.5% (1.00 cm²) while exhibiting enhanced stability. Notably, we demonstrate an impressive efficiency of 25.59% (certified at 25.36%) in a 0.06 cm² area for the inverted champion device, showcasing the promise of ferroelectric SAMs for PSCs performance enhancement.

The instability of hybrid wide-bandgap (WBG) perovskite materials (with bandgap larger than 1.68 eV) still stands out as a major constraint for the commercialization of perovskite/silicon tandem photovoltaics, yet its correlation with the facet properties of WBG perovskites has not been revealed. Herein, we combine experiments and theoretical calculations to comprehensively understand the facet-dependent instability of WBG perovskites. We find that the (111) facet, which owned higher ion-migration activation energy and lower diffusion constant, endured instability better than the (100) facet in multi-component 1.68 eV perovskites under electron beam or light irradiations, where excess charge carriers facilitate halide migrations and thereafter phase segregations. By introducing trioctylphosphine oxide into the WBG perovskite, a strong oriented growth of the (111) facet for the WBG perovskite film was realized which exhibited enhanced operational stability against light illumination. The fabricated one square centimeter area perovskite/silicon tandems with n-i-p and p-i-n configurations deliver efficiencies of 28.03 % and 30.78 % (certified 30.26 %), respectively, with both configurations exhibiting excellent operational stability at the maximum power point (MPP) with T₉₅ > 1000 h.

Tunnel oxide passivated contact (TOPCon) silicon solar cells are rising as a competitive photovoltaic technology, seamlessly blending high efficiency with cost-effectiveness and mass production capabilities. However, the numerous defects from the fragile silicon oxide/c-Si interface and the low field-effect passivation due to the inadequate boron in-diffusion in p-type polycrystalline silicon (poly-Si) passivated contact reduce their open-circuit voltages (V_OCs), impeding their widespread application in the promising perovskite/silicon tandem solar cells (TSCs) that hold a potential to break 30% module efficiency. To address this, we have developed a highly passivated p-type TOPCon structure by optimizing the oxidation conditions, boron in-diffusion, and aluminium oxide hydrogenation, thus pronouncedly improving the implied V_OC (iV_OC) of symmetric samples with p-type TOPCon structures on both sides to 715 mV and the V_OC of completed double-sided TOPCon bottom cells to 710 mV. Consequently, integrating with perovskite top cells, our proof of concept of 1 cm² n-i-p perovskite/silicon TSCs exhibit V_OCs exceeding 1.9 V and a high efficiency of 28.20% (certified 27.3%), which paves a way for TOPCon cells in the commercialization of future tandems.