Suppressing ion migration in metal halide perovskite via interstitial doping with a trace amount of multivalent cations

Cations with suitable sizes to occupy an interstitial site of perovskite crystals have been widely used to inhibit ion migration and promote the performance and stability of perovskite optoelectronics. However, such interstitial doping inevitably leads to lattice microstrain that impairs the long-range ordering and stability of the crystals, causing a sacrificial trade-off. Here, we unravel the evident influence of the valence states of the interstitial cations on their efficacy to suppress the ion migration. Incorporation of a trivalent neodymium cation (Nd3+) effectively mitigates the ion migration in the perovskite lattice with a reduced dosage (0.08%) compared to a widely used monovalent cation dopant (Na+, 0.45%). The photovoltaic performances and operational stability of the prototypical perovskite solar cells are enhanced with a trace amount of Nd3+ doping while minimizing the sacrificial trade-off. Ion migration has a detrimental effect on the performance and stability of halide perovskite optoelectronics. Here, the authors incorporated a small dosage of high-valence neodymium cation to suppress this, with a minimal impact on the lattice microstrain.

Automated summary

Cations with suitable sizes can inhibit ion migration and improve the performance and stability of perovskite optoelectronics. However, interstitial doping leads to lattice microstrain and sacrifices long-range ordering and stability. The valence states of interstitial cations have a significant influence on their efficacy to suppress ion migration.