Restrictive Heterointerfacial Delamination in Flexible Perovskite Photovoltaics Using a Bifacial Linker

Abstract Flexible perovskite solar cells offer significant potential for portable electronics due to their exceptional power density. However, the commercialization of these devices is hampered by challenges related to mechanical flexibility, primarily due to inadequate adhesion between the perovskite absorber layer and the flexible substrate. Herein, this delamination issue is addressed by employing a bifacial linker, potassium benzyl(trifluoro)borate (BnBF 3 K), to enhance adhesion at the SnO 2 /perovskite interface. This approach not only improves the mechanical stability of flexible perovskite devices but also reduces buried surface defects and optimizes energy level alignment. Consequently, a record efficiency of 21.82% (certified at 21.39%) is achieved for a flexible perovskite solar module with an area of 12.80 cm 2 and a high efficiency of 24.15% for a flexible perovskite solar cell. Furthermore, the flexible modules exhibit outstanding mechanical flexibility, retaining 96.56% of their initial efficiency after 6000 bending cycles, demonstrating their suitability for various practical applications.