Figure 6.

(a) X-ray diffractogram of the precipitate in the PbI₂ solution and (b) corresponding high-resolution XPS core level scan of the Pb-4f binding energy region, together with the deconvolution into single components. (c) X-ray diffractogram of the precipitate in the SnI₂ solution and (d) corresponding high-resolution XPS core level scan of the Sn-3d binding energy region (blue circles), together with the deconvolution into single components. The spectrum of a degraded Sn-based perovskite film (representing SnI₂) is added as a comparison (black circles). Binding energy reference values can be found in Table S1. Note that there is no binding energy for Pb(OH)I available but it will likely coincide with that of Pb(OH)₂.