Buried Interlayer Induced 1D Perovskite Seeds Enable Over 31%‐Efficiency Perovskite/TOPCon Tandem Solar Cells

Regulating the crystallization of wide-bandgap perovskite films through 1D perovskite engineering is an effective strategy to enhance the efficiency and stability of perovskite/TOPCon tandem solar cells. However, the formation of 1D perovskite at the buried interface to regulate crystallization and optimize interface contact is an attractive and challenging research topic. Tetra-n-butylammonium dichlorobromide (TBADCB) at the buried interface is introduced. The larger dipole moment and higher binding energy promote the preferential formation of 1D perovskite at the buried interface, allowing 1D seeds to form below the thermodynamic phase transition temperature. The 1D seeds provide the crystal nucleus and induce the FA-based perovskite to crystallize from bottom to top under solvent annealing, releasing the residual stress. The results show that the open circuit voltage (V_OC) and fill factor (FF) of single-junction wide bandgap perovskite solar cells are significantly improved, and the power conversion efficiency (PCE) reaches 21.45%. The initial efficiency of the packaging device is maintained at 80% after continuous illumination for 700 h (AM 1.5G) under 50-60% humidity conditions. In addition, this method enables the certification efficiency of perovskite/TOPCon tandem solar cells to exceed 31%.