  Tandem solar cells are at the forefront of extending the efficiency limits of
solar cell technology. Among two-terminal tandems, current-matched (CM) tandem
solar cells are of particular interest, owing to their relative ease of
fabrication. Though CM tandems have been extensively studied, an analytical
framework based on the detailed balance for N-layer CM tandems with area
de-coupled subcells has not been addressed. Current matching constraints can be
alleviated with the addition of area de-coupled subcells/modules at each layer
appropriately. In this work, we propose an analytical framework for modeling
the performance limits of an N-layer CM tandem solar cell with subcells across
layers. Radiative coupling among cells is taken into account. Analytical
expressions for the optimal number of subcells across layers are presented.
This may provide design guidelines for designing and estimating the performance
limits of advanced solar cell architecture and can be extended to
voltage-matched and bifacial devices as well.
