Optical analysis and optimizations of semi-transparent triple cation perovskite solar cells for tandem applications

4-terminal tandem solar cells with an efficiency of 21.7% was synthesized and modelled, combining a semitransparent perovskite solar cell (PSC) as top cell with an efficiency of 16.6% and a commercially-available Aluminium Back Surface Field (Al-BSF) silicon bottom cell. In order to further improve the efficiency of the tandem solar cell, the parasitic optical losses in the PSC have to be minimized, mostly in the near infrared region (NIR), in order to optimize the efficiency of the silicon cell. The modelling of the optical path into the PSC was obtained with the transfer matrix method in order to identify precisely the losses and to optimize the tandem cells. Two interfaces with the air appear critical to decrease parasitic reflection, and the TCO layers and the substrate are mainly responsible for absorption in the NIR. A first optimization allow to improve the efficiency at 23.2% by replace the soda-lime glass, using an anti-reflection coating on the glass-air interface and a interlayer between the silicon and the perovskite cell. A second improvement concerns the two FTO and ITO electrodes, and show that a reduction of their absorption by 10 allow to reach 23.7% (+2%). Finally, the simulated tandem cell reaches 25.5% (+3.8%) when all the improvements are combined. Thus, this work aims to quickly test the interest of various materials, by the prediction of the optical properties of the PSC and their impact on the efficiency of the bottom silicon cell and in consequently the complete tandem cell.