Design and Multiphysics Modeling of Robust SWCNT/NiO Core–Shell Hole Transport Layers in All‐Perovskite Tandem Solar Cells

This study employs advanced 3D opto‐electro‐thermal (OET) simulations based on the finite element method to analyze and optimize perovskite tandem solar cells (TSC) featuring CsPbI ₃ /MASnI ₃ active layers. The study includes a comprehensive physical analysis of the OET behavior within the device, providing deep insights into electromagnetic wave interactions, carrier dynamics, and heat management. The main challenge is enhancing bottom subcell (BS) performance by integrating a single wall carbon nanotube (SWCNT)/NiO core–shell as the hole transport layer (HTL). The reference TSC initially exhibits a power conversion efficiencies (PCE) of 19.55%. After thickness optimization of the active layers, the PCE increases to 22.88%, with balanced J _sc and slightly reduced V _oc . Subsequently, incorporation of the SWCNT/NiO core–shell HTL further enhances device performance, leading to a maximum PCE of 25.11% with improved thermal management in the BS. Comprehensive OET analysis shows reduced thermal losses, while useful output power in the BS increases from 14.13% to 20.28% of the incident power. Furthermore, parametric sensitivity analyses show that the SWCNT/NiO core–shell HTL maintains robust performance under realistic parameter variations, demonstrating that precise nanostructured HTL engineering enhances electrical efficiency, thermal stability, and the durability of perovskite TSCs.