Innovations in Interconnecting Layers for Perovskite-Based Tandem Solar Cells

Monolithic tandem solar cells (TSCs) are the most practical design to surpass the Shockley–Queisser limit in single-junction photovoltaics. The metal halide perovskites have provided a new option for combining photoabsorbers in TSCs, and various types of perovskite-based TSCs have been developed so far. The performance of TSCs heavily relies on the properties of interconnecting layers (ICLs), which bond two adjacent subcells while providing electrical, optical, and mechanical interconnections. Herein, we present a comprehensive analysis of the ICLs within perovskite-based TSCs. The discussion commences with a definition of ICLs and, subsequently, the evolution of ICLs in various kinds of perovskite-based TSCs is described. The following sections delve into the progress made in flexible TSCs and large-area modules. The cost of ICLs is then analyzed to optimize their efficiency for TSCs while minimizing the expenses. The paper concludes with a summary and presents the future prospects for developing robust ICLs for TSCs.