Synthesis, characterization and optoelectronic properties of chemically stable (CH3)3SPbI3-xBrx and (CH3)3SPbI3-xClx (x=0, 1, 2, 3) perovskites

We report on the novel series of (CH3)(3)SPbI3-xBrx and (CH3)(3)SPbI3-xClx (x = 0, 1, 2, 3) perovskite compounds, X-ray diffraction analysis shows that the solid solutions of (CH3)(3)SPbI3-xClx (x = 0, 1, 2, 3) and (CH3)(3)SPbI3-xClx (x = 0, 1, 2) crystallize in hexagonal symmetry (space group P6(3)mc, No. 186) with 1D columns of face-sharing [PbX6] octahedra. (CH3)(3)SPbCl3 crystallizes in orthorhombic symmetry (space group Pnma, No. 62) forming 3D network of vertex- and face-sharing [PbCl6] octahedra. Optical and vibrational properties were investigated using UV-vis reflectance, photoluminescence and Raman spectroscopy at room temperature. The compounds show high chemical stability in ambient air at temperatures up to 80 degrees C and under solar simulator, in contrast to the hygroscopic CH3NH3PbI3 or CH(NH2)(2)PbI3 that are commonly used in perovskite solar cells. First principles theoretical ab initio and efficient semiempirical extended Huck&calculations were performed to evaluate the energy band gap values, whose results are in good agreement with the experimentally determined values. (C) 2017 Elsevier Ltd. All rights reserved.