Unraveling Thermal Accumulation in Perovskite/Silicon Tandems: Structure- and Material-Driven Heating in SHJ, TOPCon, and TBC Bottom Cells

Perovskite/silicon (PVK/Si) tandem solar cells approach 35% efficiency, while near-infrared (NIR)-induced thermal accumulation severely restricts their operational stability. This work reveals structural and material heating origins of three mainstream silicon bottom sub-cells: SHJ, TOPCon, and TBC. Under NIR irradiation, the SHJ bottom cell shows the highest steady-state temperature (65.2 °C) and maximum efficiency loss (7.91% at 150 °C) due to its rear texture extending the NIR optical path and low-thermal-conductivity ITO/a-Si:H layers. In contrast, the TBC bottom sub-cell with a planar rear surface and high-thermal-conductivity SixNy/poly-Si stack presents the weakest heat buildup and best stability with only 5.86% PCE decay. IEC-standard long-term thermal aging tests confirm the serious performance degradation of SHJ bottom sub-cell. COMSOL simulations validate our findings in both 2T and 4T tandem configurations. This work offers useful references for thermally driven bottom-cell selection among the studied architectures, toward efficient, stable, and industrially viable PVK/Si tandem solar cells.