Multiphysics Insights into Carrier‐Ion Interactions and Electrochemical Reactions in Perovskite/Silicon Tandem Solar Cells

Abstract Mobile ions, widely present in perovskite devices, play a pivotal role not only in modulating carrier dynamics but also in facilitating electrochemical reactions, ultimately compromising device efficiency and operational stability. However, the intricate multi‐physical mechanisms governing carrier‐ion interactions and multi‐particle‐coupled electrochemical reactions pose substantial challenges to improving device performance. This is particularly relevant for perovskite/silicon tandem solar cells (TSCs), which feature complex multilayer architectures and intricate interfacial interactions. In this study, a self‐consistently coupled multi‐physics simulation model for perovskite/silicon TSCs is developed that integrates carrier transport, ion migration, and electrochemical reactions, with the aim of elucidating the fundamental mechanisms underlying carrier‐ion interactions and proposing viable optimization strategies. The simulations reveal that ionic reactions significantly influence carrier and ion distributions, potentially inducing energy losses that degrade device performance, while also partially compensating for efficiency degradation arising from energy‐band misalignment. Specifically, cations exhibit a pronounced tendency to react with electrons under reverse bias scanning, leading to substantial reaction‐induced losses and severe performance degradation, whereas anions demonstrate stronger reactivity with holes under forward bias scanning. This work provides fundamental insights into the carrier‐ion‐electrochemical interplay in perovskite/silicon TSCs, thereby offering valuable guidance for the development of high‐efficiency and stable perovskite‐based devices.