Rational Interface Design Toward Mechanically Durable Flexible Perovskite Solar Cells

Owing to distinctive properties of lightweight, thin, high energy-to-mass ratio and bendability, flexible perovskite solar cells (f-PSCs) are expected to extend the application scenarios of photovoltaics, while the defective and fragile interface within the devices seriously restricted their mechanical stability and practical deployment. Herein, the origin of the flexibility of the perovskite lattice is explored and historic progress of the f-PSCs is briefly summarized. Then, the fracture mechanics of the f-PSCs and relevant mechanical characterizations are introduced. Recent strategies to boost the mechanical durability of the f-PSCs are systematically reviewed from the aspect of interface design, including the regulation of perovskite crystallization with optimum crystallinity and suppressed lattice strain, construction of grain boundary patches to eliminate the difference of mechanical properties between grain and grain boundaries, facilitating energy dissipation from fragile perovskite to adjacent elastic layers, and strengthening interfacial contact with improved fracture resistance. In the end, perspectives in the further development toward efficient and mechanically robust f-PSCs are provided.