Finding junction partners for CsPbI3 in a two-terminal tandem solar cell: A theoretical prospect

Abstract Screening ideal partner materials for the CsPbI3 perovskite is crucial for developing all-inorganic perovskite-based tandem solar cells. Here, we quantize the performance of all-inorganic tandem solar cells combining the CsPbI3 perovskite with c-Si, GaAs, CdTe, CIGS, and CsSnI3, by analyzing the measured spectral efficiencies and developing macroscopic continuum device (MCD) model. Firstly, we integrate the MCD model and the principles of detailed balance (Shockley-Queisser limit model, SQM) to investigate the top CsPbI3 solar cell with varying thickness and the rear sub-cell with different bandgaps. Without considering the nonradiative recombination and absorptivity in the rear sub-cell, an efficiency of over 32% can be reached by selecting the low bandgap materials (Egap ~ 1.1 eV) as the rear sub-cell. Furthermore, after the simulation by MCD model that takes the charge recombination, absorptivity and optimal thicknesses for both sub-cells in tandem architectures into account, CIGS is found to be one of the best junction partners for CsPbI3. During the simulations, a unique bisection search algorithm is used to guarantee that the continuity of electric potential near the junction layer and the current matching of sub-cells in the tandem solar cells. As a result, a CsPbI3(470 nm)/CIGS(2000 nm) tandem solar cell with the best-modeled efficiency of 24.40% can be achieved, which is affirmed by a recent experimental result. Finally, we simulate the corresponding bifacial tandem photovoltaic device, and the optimal modeled efficiency can be further enhanced to 25.58%.