In this letter, methylammonium lead iodide (MAPbI3) thin films were examined via piezoresponse force microscopy (PFM) and nanoindentation (NI) to determine if long range atomic order existed across the full width of the apparent grains. From the PFM, the piezoelectric response of the films was strongly correlated with low-index planes of the crystal structure and ferroelectric domains in macro-scale solution-grown MAPbI3 crystals, which implied long-range order near the top surface. From the NI, it was found that the induced cracks were straight and extended across the full width of the apparent grains, which indicated that the long-range order was not limited to the near-surface region, but extended through the film thickness. Interestingly, the two MAPbI3 processes examined here resulted in subtle differences in the extracted electro-mechanical and fracture properties, but exhibited similar power conversion efficiencies of > 17 % in completed devices.
Citation: ACS Applied Materials and Interfaces
Pub Type: Journals
Perovskite, photovoltaic, piezoresponse force microscopy, nanoindentation