Synergetically Optimized Perovskite Subcells with a VOC beyond 2 V in Tandem Architecture

The two-terminal all-perovskite tandem cell is simulated using a one-dimensional solar cell capacitance simulator. The device structure introduced in this work utilizes FA0.8Cs0.2Pb(I0.7Br0.3)3 and (FASnI3)0.6(MAPbI3)0.4:Cl perovskite materials with a 1.75 and 1.25 eV band gap as the top and bottom cell, respectively. The top and bottom cell with different electron transport layer and hole transport layer combinations are used to understand the band alignment compatibility along with charge carrier dynamics in the devices to achieve higher performance. The top and bottom cell are first simulated individually and achieved efficiencies of 19.63 and 24.83%, respectively. For the tandem solar cell, current matching conditions are met by varying thicknesses of the absorber layer in both the top and bottom cell. Finally, the simulated optimized all-perovskite tandem solar cell showed a power conversion efficiency of 31.82% with an open circuit voltage of 2.049 V. This work opens a pathway to discuss the strategy to enhance the performance of perovskite tandem solar cells through simulation understanding.