Fig. 5: Hardnesss measurements.
From: Nanomechanical signatures of degradation-free influence of water on halide perovskite mechanics
a NI Hardness results. Solid bars represent measurements performed in the dry state; dotted bars represent measurements performed in the humid state. The percentage values here and in c–d represent the difference between dry and humid states for each set (see text and Fig. 2 caption). b Illustration of the indentation process, defining hmax and hf, and explaining the trade-off between the elastic and plastic deformation in FAPbBr3. c Ratio hf/hmax for each of the 5 crystals under the different humidity conditions. As shown schematically in b, hmax is the depth at maximum load, and hf is the residual depth remaining after the indenter unloads to zero load. The ratio for each crystal increases slightly in the humid state, except for FAPbBr3, where the change is dramatic. d Traditional hardness (TH), calculated from the projected area of residual imprints in the AFM images for all 5 crystal types under dry and wet conditions as described in experimental section. Error bars in a,c, and d represent standard deviation in the measurements.
