Effects of PEAI Post-treatments on the Ion Migration in Lead Iodide Perovskites

In recent years, perovskite solar cells (PSCs) have emerged as a new generation of photovoltaic devices, with power-conversion efficiencies (PCEs) now approaching ∼26%. Despite the high PCEs, the unsatisfactory device stability is the main issue preventing the practical applications of PSCs. An organic halide salt, phenethylammonium iodide (PEAI), was reported to be an effective surface passivator used in the post-processing of PSCs for PCE enhancements [1]. The PEAI post-treatment could also improve device stability, which may be affected by various factors including ion migration in the halide perovskite materials. In this work, we investigate the influence of PEAI post-processing on the ion migration processes in FA
1−x
MA
x
PbI
3
perovskite. We find that PEAI post-processing can effectively reduce the ion mobilities from 1.2×10
⁻⁷
cm
²
V
⁻¹
s
⁻¹
to 5.7×10
⁻⁸
cm
²
V
⁻¹
s
⁻¹
in FA
1−x
MA
x
PbI
3
films, and the hysteresis index (HI) from 0.243 to 0.034 in PSCs. The suppression effects of PEAI post-treatment on ion migration exhibit an initial enhancement at low concentrations, followed by a reduction at higher concentrations. Our results may contribute to the understanding of the possible improvements in the long-term stability of PEAI-treated PSCs.