Redefining Crystalline Silicon: Unlocking New Horizons in Transparent and Flexible Photovoltaics

Crystalline silicon ( c ‐Si) underpins the global photovoltaic industry owing to its high efficiency, material abundance, and proven field reliability. This maturity, however, reinforces the view that silicon is intrinsically tied to rigid, opaque module formats. This review revisits that assumption and surveys how advances in optical and mechanical design transform c ‐Si into a transparent and mechanically compliant photovoltaic platform. First, the design principles of selective light‐transmission architectures are elucidated, in which geometrically defined micro‐apertures and module‐level optical management decouple visible transparency from photovoltaic absorption, enabling neutral‐color appearances suitable for architectural integration. Subsequently, stress‐redistribution strategies—including ultrathin wafer engineering, neutral‐axis and hierarchical structuring, and microstructured interconnects—are examined, which address the intrinsic brittleness of the silicon lattice and permit substantial flexibility while maintaining high electronic quality. Beyond structural concepts, emerging routes such as singlet‐fission–based spectral conversion and tandem integration are discussed, which, at least at the theoretical level, offer pathways to surpass the conventional single‐junction efficiency limit in transparent or flexible silicon‐based devices. Together, these developments recast c ‐Si from a mature but static technology into an evolving, versatile semiconductor platform for transparent and flexible photovoltaics, with the potential to integrate power generation directly into the built environment and other form‐factor‐constrained systems.