Fabrication and characterization of organic-inorganic perovskite films containing fullerene derivatives

The layered perovskite, (RNH3)2PbX4 (R = alkyl group, X = halogen), which contained the fullerene ammonium derivative, N-methyl-2-(4-aminophenyl)-fulleropyrrolidine iodide (AmPF), in the organic layers, was fabricated as a thin solid film. X-ray diffraction measurement of the obtained films revealed that AmPF molecules were introduced to the organic layers, however, the obtained film was heterogeneous. The homogeneous perovskite films were fabricated by addition of dodecylammonium iodide as a supporting material to AmPF. It was found that the layered structures of two-dimensional perovskites changed depending on the rate of AmPF in the organic ammonium layers from the results of X-ray diffraction. UV-vis absorption spectra of the films were also changed by incorporation of AmPF molecules. By increasing the rate of fullerene, new peak at 560 nm was appeared while the exciton peak at 511 nm of the conventional layered perovskite diminished. This suggested that the exciton binding energy was transported from the exciton state of the conventional perovskites to the lower energy state formed by fullerene derivatives in the organic layers.