A Comprehensive Study of Carrier Transport Mechanisms and Interface Recombination in Perovskite-Silicon Tandem Solar Cells for High-Efficiency Applications

Background: Perovskite-silicon tandem solar cells represent the most promising near-term pathway to exceed the Shockley-Queisser single junction limit, yet interface recombination at the perovskite-silicon heterojunction remains a primary barrier to theoretical efficiency limits. Aim: This study comprehensively investigated carrier transport mechanisms and interface recombination in perovskite-silicon tandem solar cells through combined experimental and modelling approaches. Methods: Four-terminal and two-terminal tandem cell configurations were fabricated using methylammonium lead iodide perovskite top cells and passivated emitter and rear silicon bottom cells. Temperature-dependent current-voltage and admittance spectroscopy characterised carrier transport mechanisms. Drift-diffusion simulations using SCAPS-1D modelled interface recombination effects. Interface passivation by self-assembled monolayers was evaluated. Results: Interface recombination velocity at the perovskite-silicon junction was measured at 340 cm/s in unpassivated cells, reduced to 85 cm/s by self-assembled monolayer treatment. Tandem efficiency improved from 23.1% to 27.4% after interface passivation. Dominant carrier transport was identified as trap-assisted tunnelling at the interface. Conclusion: Interface passivation through self-assembled monolayers is the most effective strategy for suppressing recombination in perovskite-silicon tandems. The mechanistic understanding developed enables rational optimisation of tandem cell architectures. Keywords: perovskite-silicon tandem, carrier transport, interface recombination, self-assembled monolayer, solar cell efficiency.