Efficiency evaluation for triple-junction solar cells in five tandem configurations

For triple-junction solar cells (3J SCs), five tandem configurations have been successively put forward, including two-terminal serial, six-terminal, parallel/serial, bottom-cell-independent and top-cell-independent configurations. However, comprehensive studies on efficiencies of 3J SCs in the five configurations are few, and comparisons of the above five configurations are scarcer. This work evaluates efficiencies of 3J SCs in all the five configurations, and meanwhile analyzes the strong and weak points of the five configurations in spectral robustness and efficiencies. The limiting efficiencies for 3J SCs with three direct-bandgap subcells are firstly calculated based on the detailed balance theory. Previous works mainly provided the highest efficiencies and the corresponding subcell bandgaps. In this work, along with the highest efficiencies, efficiency contour plots for all the five configurations are offered. Then the emphasis is focused on 3J SCs with a crystalline silicon (c-Si) bottom cell. Organic cation lead halide perovskite materials have shown a huge development potential in photovoltaic field. Possessing the wide tunable bandgap ranges, perovskite materials are promising candidates for the top and middle cells. Hence, simulations and recommendations for practical approaches of the perovskite/perovskite/c-Si 3J SC are given, where the perovskite subcells have appropriate bandgaps according to the above calculated results.