Figure 4
In-situ HR-XPS spectra determined under different temperature conditions for (a) Pb 4 f (recorded with an excitation energy of 200 eV), (b) I 4d (200 eV), and (c) N 1 s (500 eV) of MAPbI3. (d) Changes in the N/Pb and I/Pb ratios as a function of heat exposure.
