Advances in Perovskite/C60 Interface Engineering for Efficiency and Stability in Perovskite/Silicon Tandem Solar Cells

Abstract

Perovskite/silicon tandem solar cells (TSCs) have emerged as a leading photovoltaic technology to surpass the Shockley–Queisser efficiency limit of single-junction devices. In this architecture, the interfacial properties between the perovskite absorber and the electron transport layer (ETL) critically govern charge extraction, non-radiative recombination losses, and long-term operational stability. Among the various ETL materials, fullerene C60 and its derivatives are widely employed owing to their favorable energy-level alignment with perovskites, high electron mobility, and compatibility with low-temperature processing. Nevertheless, non-ideal interfacial contact, interfacial energy-level mismatch, intrinsic defect states, and ion-induced interfacial degradation at the perovskite/C60 heterointerface remain key bottlenecks limiting the efficiency and stability of tandem devices. This review systematically examines recent advances in interfacial engineering strategies at the perovskite/C60 interface, focusing on approaches that suppress phase segregation, passivate interfacial defects, tailor energy-level alignment, and mitigate ion migration. We further summarize the implementation of these strategies in high-efficiency perovskite/silicon TSCs, covering both small-area devices and scalable large-area modules, with particular emphasis on processing compatibility and operational stability. Finally, we discuss the remaining scientific and technological challenges and outline future research directions toward robust, manufacturable, and industry-compatible perovskite/silicon tandem photovoltaics.