Isomerizing Passivators in Perovskite Solar Cells: The Impact of Molecular Spatial Configuration

Defect passivation, relying on the interaction between passivators and the perovskite lattice, effectively improves the photoelectric performance of perovskite solar cells. Nevertheless, the principles for designing passivators, such as tuning molecular configuration and electrostatic potential, can sometimes be invalid even with those widely reported functional atoms and groups, showing an uncovered missing factor in current passivating mechanisms. Herein, by carefully comparing the isomerism of passivators, we unearth that the spatial position of functional atoms on the passivators plays a key role in determining their passivating capabilities. We find that the passivation becomes stronger when the spacing of functional atoms matches that of lead ions in between the neighboring lattice. Interestingly, by utilizing such a strategy, we achieve strong passivation from a passivator even with weak electrostatic potential. Eventually, we stepwise increase the device performance from a baseline of 22.74% to 23.30%/23.88%/24.60% with improved device stability, showcasing the advantage of optimizing molecular spatial configuration for passivators.