Over 29%-efficient, stable n-i-p monolithic perovskite/silicon tandem solar cells based on double-sided poly-Si/SiO₂ passivating contact silicon cells

Perovskite/silicon (Si) tandem solar cells (TSCs) continue to rapidly advance. The majority of the monolithic perovskite/Si TSCs have been built on heterojunction (HJT) Si solar cells, which have seen limited industrial uptake due to manufacturing cost and concern over the viability of metal electrodes and transparent conductive oxides (TCOs) incorporating expensive elements. In this work, we demonstrate that high efficiencies of perovskite/Si TSCs can be achieved with Si bottom cells based on a double-side poly-Si/Si dioxide (SiO₂) passivating contact (poly-Si cell) without silver or TCOs, fabricated using mass-production techniques. Meanwhile, a novel low-absorption, dopant-free bilayer-structured hole transport layer (HTL) composed of ultra-thin poly(N,N′-bis-4-butylphenyl-N,N′-bisphenyl)benzidine (Poly-TPD) and 2,2′,7,7′-tetra(N,N-di-p-tolyl)amino-9,9-spirobifluorene (Spiro-TTB) double layers was developed for the perovskite top cell, which passivates the perovskite surface and enhances the near-interface conductivity, thus increasing the open-circuit voltage and fill factor. A power conversion efficiency of more than 29% was achieved, the highest for a perovskite/Si TSC based on poly-Si bottom cells and/or n-i-p perovskite top cells reported to date. Moreover, the tandem cells exhibit exceptional thermal and light stability, retaining their original output without loss after undergoing 1750 hours of light-dark cycles. Under continuous one-sun illumination and a bias near the maximum power point at 55 ± 5 °C, the tandem devices maintained 93% and 89% of their initial PCE after 500 hours and 1782 hours, respectively. These results pave the way for large-scale manufacturing of industrially viable perovskite/Si TSCs in the near future.