Four-Terminal All-Perovskite Tandem Solar Cells Achieving Power Conversion Efficiencies Exceeding 23%

We report on fabrication of 4-terminal all-perovskite tandem solar cells with power conversion efficiencies exceeding 23% by mechanically stacking semitransparent 1.75 eV wide-bandgap FA 0.8 Cs 0.2 Pb(I 0.7 Br 0.3 ) 3 perovskite top cells with 1.25 eV low-bandgap (FASnI 3 ) 0.6 (MAPbI 3 ) 0.4 bottom cells. The top cells use MoO x /ITO transparent electrodes and achieve transmittance up to 70% beyond 700 nm.