Molecular Bridge in Wide-Bandgap Perovskites for Efficient and Stable Perovskite/ Silicon Tandem Solar Cells

Perovskite/silicon tandem solar cells (TSCs) attract intensive attention because of their potential to deliver power conversion efficiencies (PCE) beyond those of their single-junction counterparts. However, the performance and stability of tandem devices are limited by defect-assisted non-radiative recombination and light-induced halide segregation in wide-bandgap (WBG) perovskite sub-cells. Here, 2-aminoethanesulfonamide hydrochloride (AESCl), with multi-point chelation sites and bridging capability, is incorporated into a 1.68 eV WBG perovskite to comprehensively passivate defects at grain boundaries and surfaces. As a result, AESCl-treated perovskite films show suppressed halide segregation and a champion WBG single-junction solar cell achieves an impressive efficiency of 22.80% with an open-circuit voltage of 1.286 V due to reduced non-radiative recombination. The efficient WBG perovskite sub-cells enable perovskite/silicon TSCs to reach a champion PCE of 30.36% over 1 cm2. Moreover, the tandem devices retain over 96% of their initial efficiency after operation for 1068 h under continuous AM 1.5G illumination at 25 degrees C in ambient air.