Fig. 3: Electronic structure and chemical bonding evolutions during the degradation.
From: Atomic-scale imaging of CH3NH3PbI3 structure and its decomposition pathway
a, b Electronic structures of MAPbI3 and MA0.5PbI3. The Fermi level is set to zero. c Time-series CL spectra showing the bandgap gradually increases from 1.6 eV to 2.05 eV. The dashed lines show the calculated bandgaps at 1.56, 1.69 and 2.15 eV for MAPbI3, MA0.5PbI3 and 6H-PbI2, respectively. d Time-series vibrational spectra under ‘aloof’ mode with the electron probe ~30 nm away from MAPbI3. Black arrows indicate the peaks related with CH3-NH3+ rock, CH3 bend and NH3+ stretch. The background was subtracted by the power-law function. e Evolutions of normalized intensities of CH3 bending (cyan circles) and CH3-NH3+ rock (orange squares) during the degradation. Inset is the schematic diagram of ‘aloof’ mode showing the electron probe is ~30 nm away from MAPbI3 for the vibrational spectroscopy measurements.
