Rationally designed universal passivator for high-performance single-junction and tandem perovskite solar cells

Interfacial trap-assisted nonradiative recombination hampers the development of single junction and tandem perovskite solar cells (PSCs). Herein, we report a rationally designed universal passivator to realize highly efficient and stable single junction and tandem PSCs. Multiple defects are simultaneously passivated by the synergistic effect of anion and cation. Moreover, the defect healing effect is precisely modulated by carefully controlling the number of hydrogen atoms on cations and steric hindrance. Due to minimized interfacial energy loss, L-valine benzyl ester 4-toluenesulfonate (VBETS) modified inverted PSCs achieve a power conversion efficiency (PCE) of 25.26% (certified 25.15%) for PSC devices and 21.00% for the modules with an aperture area of 32.144 cm². The efficiency values both are the record PCEs ever reported for the inverted PSCs using vacuum flash technology in ambition conditions. Further, by suppressing carrier recombination, the perovskite/Si tandem solar cells coupled with VBETS passivation deliver a PCE of 30.98%. This work highlights the critical role of the number of hydrogen atoms and steric hindrance in designing molecular modulator to advance the PCE and stability of PSCs.