Performance Evaluation of Semitransparent Perovskite Solar Cells for Application in Four-Terminal Tandem Cells

The
efficiency of perovskite-based tandem solar cells and the respective
efficiency gain over the single-junction operation of the bottom cell
strongly depend on the performance of the component cells. Thus, a
fair comparison of reported top cells is difficult. We therefore compute
the tandem cell efficiency for the combination of several semitransparent
perovskite top solar cells and crystalline silicon or chalcopyrite
bottom cells from the literature. We focus on four-terminal configurations
but also estimate and discuss the differences between four- and two-terminal
configurations. For each top cell, we thereby determine the tandem
cell performance as a function of the bottom cell efficiency, which
results in a linear relationship. From these data, we extract two
parameters to quantify the suitability of the top cell: (i) the slope
of the tandem vs. bottom cell efficiency, which is the effective transparency
of the top cell, and (ii) the tandem cell efficiency for a targeted
bottom cell. These two figures of merit were calculated for a representative
set of bottom cells and may serve for comparison of semitransparent
perovskite top cells in the future.