Rough Hole‐Transport Layer for Nucleation Control Enables High‐Efficiency Perovskite/Silicon Tandem Solar Cells on Fully Textured Silicon

Achieving complete perovskite coverage on commercial fully textured silicon photovoltaics remains a critical challenge for high‐efficiency perovskite/silicon tandem solar cells. Here, we report a hole‐transport‐material (HTM) nanoparticle‐guided nucleation strategy by uniformly decorating micrometer‐scale pyramids with spray‐coated NiO x nanoparticles. A spray‐on‐hot‐substrate process enables conformal deposition of NiO x nanoparticles across pyramid tips, sidewalls, and valleys, forming a rough HTM layer. An optimized NiO x thickness of 20–30 nm simultaneously provides sufficient surface roughness to regulate perovskite nucleation while preserving efficient charge transport. The NiO x nanoparticles effectively tailor local morphology angles, suppressing valley‐preferred nucleation and enabling spatially uniform perovskite nucleation and growth. Consequently, ∼1 µm‐thick perovskite films achieve complete coverage of micrometer‐scale pyramids without exposed tips. Leveraging this approach, perovskite/silicon tandem solar cells deliver a champion efficiency of 32.98%. This work demonstrates a scalable pathway toward high‐performance tandem photovoltaics by utilizing the HTM itself as an effective nucleation‐regulating layer.