Efficient Carrier Separation and Intriguing Switching of Bound Charges in Inorganic–Organic Lead Halide Solar Cells

We fabricated a mesoporous perovskite solar cell with a ∼14% conversion efficiency, and we investigated its beneficial grain boundary properties of the perovskite solar cells through the use of scanning probe microscopy. The CH₃NH₃Pb­(I_0.88,Br_0.12)₃ showed a significant potential barrier bending at the grain boundary and induced passivation. The potential difference value in the <i>x</i> = 0.00 sample is ∼50 mV, and the distribution of the positive potential is lower than that of the <i>x</i> = 0.12 sample. We also investigated the polarization and hysteretic properties of the perovskite thin films by measuring the local piezoresponse. Specifically, the charged grain boundaries play a beneficial role in electron–hole depairing and in suppressing recombination in order to realize high-efficiency perovskite solar cells