  In this study, the optoelectronic properties of a monolithically integrated
series-connected tandem solar cell are simulated. Following the large success
of hybrid organic-inorganic perovskites, which have recently demonstrated large
efficiencies with low production costs, we examine the possibility of using the
same perovskites as absorbers in a tandem solar cell. The cell consists in a
methylammonium mixed bromide-iodide lead perovskite, CH3NH3PbI3(1-x)Br3x (0 < x
< 1), top sub-cell and a single-crystalline silicon bottom sub-cell. A Si-based
tunnel junction connects the two sub-cells. Numerical simulations are based on
a one-dimensional numerical drift-diffusion model. It is shown that a top cell
absorbing material with 20% of bromide and a thickness in the 300-400 nm range
affords current matching with the silicon bottom cell. Good interconnection
between single cells is ensured by standard n and p doping of the silicon at
5.10^19cm-3 in the tunnel junction. A maximum efficiency of 27% is predicted
for the tandem cell, exceeding the efficiencies of stand-alone silicon (17.3%)
and perovskite cells (17.9%) taken for our simulations, and more importantly,
that of the record crystalline Si cells.
