Efficient and stable industrial-size perovskite/silicon tandems with long-span bisphosphonic self-assembled molecules

<title>Abstract</title> <p> With the blessing of self-assembled molecules (SAMs), the power conversion efficiency (PCE) of perovskite/silicon tandem solar cells (TSC) (~1 cm ² ) has exceeded the Shockley-Queisser limit. However, achieving uniform SAM deposition on industrial-scale textured silicon remains challenging. At present, mono-phosphonic SAMs fail to fully cover the silicon pyramid, whereas polymeric SAMs are prone to aggregation, resulting in inhomogeneous film formation. To overcome this, we designed a long-span bisphosphonic SAM ( <bold>S2</bold> ) featuring an extended π-conjugated framework and flexible C-C bonds that enable conformal coverage over industrial-size-pyramid-textured silicon surfaces. Furthermore, its bisphosphonic anchors provide stronger interfacial bonding to across the pyramid-tips and ridges, while a higher dipole moment further enhances charge transport and energy-level alignment. S2-based lab-scale TSCs deliver 34.3% efficiency (0.98 cm ² , certified 33.8%) and a certified 32.6% for 210 mm-half wafer TSC (196.97 cm ² ). Encapsulated large-size TSCs retain 91% and 93% of initial efficiency after 1000 h damp heat and 200 thermal cycles, respectively. A four-subcell integrated module maintains ~95% of its initial power after one month of outdoor operation. </p>