Interfacial passivation of wide-bandgap perovskite solar cells and tandem solar cells

Perovskite/silicon tandem solar cells offer the potential to surpass the power conversion efficiency (PCE) of single-junction solar devices beyond the Shockley-Queisser limit at relatively low costs. However, obtaining wide-bandgap materials that provide improved efficiency and appropriate stability is very challenging due to their increased trap density and frequent phase instability under light. Here we report stable wide-bandgap (similar to 1.7 eV) perovskite devices achieving efficiencies of 19.67%, and open-circuit voltages (V-oc) above 1.2 V via a suitable combination of vacuum-assisted solution processing (VASP) and interfacial passivation. Such a facile approach can be translated to multiple perovskite compositions, enabling the fabrication of efficient and stable wide-bandgap cells and their integration into monolithic silicon tandem structures with 24.01% PCE, one of the highest efficiencies for n-i-p tandem devices reported so far.