Free exciton and bound excitons on Pb and I vacancies and O and I substituting defects in PbI2: Photoluminescence and DFT calculations

•Structure, chemical composition, morphology and photoluminescence of mechanically exfoliated multilayer PbI2.•The direct free exciton peak at 2.44 eV and defect-related bound exciton peaks at 2.41, 2.35, 2.19 and 2.04 eV are found.•DFT and experimental results allow to clarify peaks: 2.41 eV to OI, 2.35 eV to VPb and 2.19/2.04 eV to IPb.•The known absorption transition at ∼ 1.55 eV is related to VI, which behaves as a nonradiative recombination center.•The thermal dissociation energy of free exciton in PbI2 is 0.22 eV.