Fig. 5: The 13C CPMAS spectra and PXRD spectra of 2D OIHP crystals (n = 2).

The 13C CPMAS spectra of a 2D (BA)2(13C,15N-MA)Pb2I7 (n = 2) and b 2D (PEA)2(13C,15N-MA)Pb2I7 (n = 2) recorded at various temperatures, ranging from 308 to 243 K. The PXRD patterns of c 2D (BA)2MAPb2I7 (n = 2) and d 2D (PEA)2MAPb2I7 (n = 2) measured at 300 K (black colour) and 250 K (blue colour). The red dashed boxes highlight the obvious changes of the 13C CPMAS and PXRD spectra during cooling.