Optical modelling of tandem solar cells using hybrid organic-inorganic tin perovskite bottom sub-cell

Three optimization algorithms, all based on the transfer matrix method (TMM), have been compared for the optical modeling of series connected tandem solar cells (TSCs). These algorithms differ in (a) the criteria for selecting which of the layers have fixed thicknesses anesses of the rest of the layers are to be varied to arrive at the optimum values. These algorithms have been applied to two organic-inorganic hybrid perovskite (OIHP) based TSCs, both using formadinium tin iodide perovskite (FASnI3) bottom sub-cell. One of these TSCs is an allOIHP device while the other is an organic semiconductor (OS)-OIHP device. The materials for active layers were chosen on the basis of bandgap requirement for high efficiency and the availability of optical constants. The maximum JPH values obtained from the three methods were 13.86, 14.424, and 14.492 mA?cm? 2 respectively for the all-OIHP TSC. The corresponding values for OS-OIHP TSC were 12.36, 12.52, and 12.55 mA?cm? 2 respectively. The effect of each of the non-active layers in the devices, including the recombination interlayer, on the reflection and parasitic absorption losses have been systematically analyzed. To minimize these losses, it has been found that, while a thin interlayer (- 5 nm) is preferable for all-OIHP TSC, a thicker interlayer (- 195 nm) is preferable for OS-OIHP TSC. While the minimized reflection and parasitic absorption losses for all-OIHP TSC were 3.71 and 0.62 mA?cm? 2, the corresponding values for OS-OIHP TSC were 6.59 and 0.73 mA?cm? 2 respectively.Also, the incident light angle dependence of JPH and the required thickness values for its maximization have been calculated. For the all-OIHP and OS-OIHP TSCs, the maximum JPH values have been obtained at the incidence angles of 15? and 0? respectively. The methods developed here are generic and can be directly applied to other TSCs as well.

Automated summary

Three optimization algorithms based on the transfer matrix method were compared for optical modeling of series connected tandem solar cells, showing their effectiveness in improving the efficiency of organic-inorganic hybrid perovskite based TSCs. The algorithms were able to optimize the maximum JPH values for different types of TSCs, demonstrating the potential for enhancing photovoltaic performance.