Preparation and characterization of natural lower dimensional layered perovskite-type compounds

Thin films of layered perovskite compounds (CnH2n+1NH3)(2)(CH3NH3)(m-1)PbmBr3m+1 (m = 1, 2 and 3) were prepared by the spin-coating method from their DMF (N,N-dimethylformamide) solutions. The control of the inorganic layer thickness in layered perovskites can be achieved by changing the ratio of the two amines (CnH2n+1NH3/CH3NH3) The layered perovskite films showed a strong, clear exciton absorption peak at room temperature due to their large exciton binding energy. With increasing numbers of inorganic layers, a red shift of the exciton absorption was observed due to the decrease in transfer energy. X-ray diffraction patterns clearly demonstrated that the spin-coated film was highly oriented normal to the surface, which is consistent with 'mono', 'bi', and 'tri' layer structures, respectively. The effect of the alkyl chain length of the organic part was also investigated. (C) 2000 Elsevier Science Ltd. All rights reserved.