Synthesis, vibrational and optical properties of a new three-layered organic-inorganic perovskite (C4H9NH3)4Pb3I4Br6

An organic-inorganic hybrid perovskite (C4H9NH3)4Pb3I4Br6 was synthesized and studied by X-ray diffraction, Raman and infrared spectroscopies, optical transmission and photoluminescence. The title compound, abbreviated (C4)4Pb3I4Br6, crystallises in a periodic two-dimensional multilayer structure with P21/a space group. The structure is built up from alternating inorganic and organic layers. Each inorganic layer consists of three sheets of PbX6 (X=I, Br) octahedra. Raman and infrared spectra of the title compound were recorded in the 100-3500 and 400-4000 cm−1 frequency ranges, respectively. An assignment of the observed vibration modes is reported. Optical transmission measurements, performed on thin films of (C4)4Pb3I4Br6, revealed two absorption bands at 474 and 508 nm. Photoluminescence measurements have shown a green emission peak at 519 nm.