Computational design of high performance hybrid perovskite on silicon 2-T tandem solar cells based on a tunnel junction

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 methyl ammonium mixed bromide-iodide lead perovskite, CH
₃
NH
₃
PbI
_3(1-x)
Br
_3x
(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
¹⁹
cm
^-3
in the tunnel junction. A maximum efficiency of about 27% is predicted for the tandem cell exceeding both the efficiencies of stand-alone silicon and perovskite cells taken for our simulations, which amount to 17,3% and 17,9%, respectively.