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

Thin films of layered perovskite compounds (CnH2n+1NH3)(2)(CH3NH3)(m-1)PbmB r3m+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 t hickness in layered perovskites can be achieved by changing the ratio of th e two amines (CnH2n+1NH3/CH3NH3) The layered perovskite films showed a stro ng, clear exciton absorption peak at room temperature due to their large ex citon binding energy. With increasing numbers of inorganic layers, a red sh ift of the exciton absorption was observed due to the decrease in transfer energy. X-ray diffraction patterns clearly demonstrated that the spin-coate d film was highly oriented normal to the surface, which is consistent with 'mono', 'bi', and 'tri' layer structures, respectively. The effect of the a lkyl chain length of the organic part was also investigated. (C) 2000 Elsev ier Science Ltd. All rights reserved.