Optical and structural effects of aniline intercalation in PbI2

Aniline has been intercalated in lead iodide thin films by exposure to aniline vapors in an evacuated chamber. X-ray diffraction and Raman spectroscopy have confirmed the presence of aniline in the interlayer space of PbI2. Intercalation leads to an increase of 0.5 eV in the optical band gap. The large increase in the band gap can be modeled by computing changes in the band structure resulting from the electrostatic interaction of the -NH2 dipole of aniline with the iodine 5pz electron. This interaction lowers and flattens the valence band along the A direction. The band-gap increase, calculated for various possible configurations of the aniline molecule, is in the range 0.35 0.57 eV.