A Multifunctional Interfacial Dipolar Molecule: Universal Applicability in Efficient Rigid, Flexible, and Large-Area...

A critical performance gap persists between lab-scale perovskite solar cells (PSCs) and their theoretical efficiency limit, primarily driven by non-radiative recombination at the electron transport layer/perovskite buried interface. Molecular engineering of this interface is a proven mitigation strategy; however, a major limitation of current modifiers is the lack of multifunctional structural design to achieve bifacial passivation, energy level alignment, and interfacial compatibility simultaneously, which typically restricts further improvements in device efficiency and the expansion of applications to large-scale and flexible substrates. To address this challenge, we design a multifunctional dipolar molecule, 2-cyanoethyl phosphate, with three features: a phosphate anchoring group for strong covalent bonding to SnO₂, a terminal cyano group for effective perovskite defect passivation, and a large intrinsic dipole moment of 5.38 Debye to optimize interfacial energy-level alignment for superior charge dynamics. This integrated strategy delivers a champion power conversion efficiency of 26.45% (certified at 26.31%) for small-area rigid PSCs, 23.51% for mini-modules (30 cm²), and 25.09% for flexible PSCs. Our work establishes a general molecular design principle for universal interfacial modifiers, accelerating the commercialization of PSCs that combine high efficiency, scalability, and flexibility.