Toward High-Performance HTL-Free All-Perovskite Tandem Solar Cells: SCAPS Simulation

Perovskite tandem solar cells have met attractive concentrations with the potential to break through the Shockley–Queisser limit in single-junction photovoltaics. However, the efficiency of all-perovskite tandem solar cells is still challenging due to the deficiency of low-bandgap Pb–Sn mixed perovskite solar cells. In this work, high-performance hole-transporting layer free (HTL-free) low-bandgap perovskite (1.29 eV) tandem solar cells are simulated with 1-D solar cell capacitance simulator. By optimizing work function, thickness, and doping concentration of the perovskite layer, the power conversion efficiency (PCE) of HTL-free perovskite device reached to 19.14%. Furthermore, the all-perovskite tandem solar cell combined this HTL-free solar cell with MAGeI ₃ (1.9 eV) top solar is studied and the current matching condition between two subcells is obtained by the optimum thicknesses of perovskite layers, which are 700 and 350 nm for the bottom and top absorbers, respectively. The all-perovskite tandem solar cell reaches a PCE of 29.1%, which is among one of the top efficiency in perovskite-based solar cells.