Synthesis and Characterization of Tin Halide Perovskites Based on Different Tin(II) precursors

Abstract Tin halide perovskite (CH3NH3SnI3) is an environmentally-friendly substitute for lead perovskite. A common precursor utilized for CH3NH3SnI3 synthesis is SnI2 despite being expensive and impractical for large scale synthesis. Also, SnI2 is prone to tin(IV) contamination, the leading cause of instability and poor performance. Here, tin(II) sulfate (SnSO4) and tin(II) octoate (C16H30O4Sn) are introduced as cheaper and stable precursors. Using the precursors including SnI2, perovskite films were synthesized by the one-step method. X-ray diffraction confirmed perovskite formation irrespective of tin precursor. However, scanning electron microscopy showed a difference in morphology. The samples synthesized with SnSO4 and C16H30O4Sn presented higher bandgaps of 1.42 eV and 1.37 eV, respectively, compared to SnI2 (1.30 eV). Elemental mapping showed that sulfur and carbon are not completely eliminated, thus must be considered when choosing non-halide precursors.