n-type regulation of 2D perovskite interlayers for efficient perovskite-silicon tandem solar cells

Interfacial defects and imbalanced charge extraction at the perovskite/C₆₀ interface in inverted solar cells drive non-radiative recombination, limiting their power conversion efficiencies (PCEs). While two-dimensional (2D) perovskite passivation layers mitigate surface defects, their inherent quantum confinement and poor conductivity hinder carrier transport and energy band alignment. Here, we present an n-type regulation strategy in 2D perovskite interlayers to simultaneously suppress defects and optimize interfacial energetics. By incorporating antimony trichloride (SbCl₃) into phenylethylammonium iodide (PEAI)-based 2D perovskites, we achieved n-type doping in the 2D passivation layer markedly enhancing its electron density, building up a field effect to enhance the passivation at the perovskite/C₆₀ interface. This controlled n-type modulation reshapes interfacial band bending, suppresses hole backflow, and reduces recombination at the interface. The resulting synergy enables efficient carrier extraction with minimal contact loss, yielding a perovskite-silicon tandem efficiency over 33% (certified 32.56%) with improved operational stability.