  Successful commercialization of Perovskite/Si tandem solar cells (P/Si TSCs)
need a-priori estimation of technological benchmarks to outperform c-Si based
technologies under field conditions. To this end, through detailed numerical
simulations and analytical modeling, here we identify the limits of ion
migration and lifetime degradation till which P/Si TSCs remain competitive. Our
results unravel a unique scaling law for the evolution of the efficiency and
the temperature coefficient of P/Si TSCs which allows us to anticipate the
limiting annual degradation rates. Interestingly, we find that 4T cells are
potentially more immune to the ill effects of ion migration as compared to 2T
cells. These insights are of broad relevance for material/interface engineering
approaches and physics based accelerated tests which are focused towards long
term stability and module reliability.
