Thin films of organic-inorganic hybrids (CnH2n+1NH3)2PbX4(X=Cl, Br, I; n=4,6,8,10) were prepared by the spin-coating method. The influences of annealing temperature on the crystal structure of the films were analyzed by X-ray diffraction(XRD). The surface morphology of the films were observed using scanning electronic microscope(SEM). The room-temperature UV-Vis absorption spectra of the films were employed to examine the effect on the optical properties of different elements X (X=Cl,Br,I), and varying n from 4 to 10, respectively. The results showed that a significant red shift of the absorption peak was observed for different X in inorganic layers, and the position of the exciton absorption peaks did not shift obviously with the increasing of the alkyl chain length in organic layers. The results suggested that the exciton absorption arise from electronic transitions within the inorganic layer, rather than from the organic layer.

As has been discussed, research on the electronic structure between organic and inorganic atoms in hybrid compounds has become important. In our study, DV-Xα method was employed to calculate the electronic structure of the hybrid compound. The information obtained from the calculation included orbit charge, bonding order, Fermi energy, density of the state, etc. The influence of organic and inorganic parts on the energy band structure of the hybrid compound was discussed based on the calculation results of Fermi energy and density of state. The chemical bonding between organic and inorganic parts in the hybrid compound was also analyzed in detail according to the orbital charges and bond orders.