High‐Performance Perovskite/Silicon Tandem Solar Cells via Ion Modulation

Low ion migration activation energy in perovskites leads to severe phase separation and structural instability, damaging the perovskite film uniformity and performance of perovskite/silicon tandem solar cells. Here, we demonstrate that ion modulation can elevate the ion migration energy barrier and improve the local structural stability of perovskite at the atomic level via density functional theory calculations and molecular dynamics simulations. High‐resolution transmission electron microscopy (HRTEM) further revealed the correlation between the ion migration activation energy and the lattice, atomic, and crystalline structure of perovskites. Consequently, we achieved multi‐dimensional (horizontal/ vertical/ microscale) uniform deposition of perovskite films through ion modulation. The target device achieved a champion power conversion efficiency of 33.02% compared with 31.12% for control. Notably, the unencapsulated target device demonstrated negligible efficiency degradation over a 1200 s maximum power point tracking test and retained more than 90% of its initial efficiency following 1000 h of ambient air storage.