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Synthesis, crystal structure, and properties of a perovskite-related bismuth phase, (NH4)3Bi2I9

last modified Aug 04, 2016 07:24 AM

Synthesis, crystal structure, and properties of a perovskite-related bismuth phase, (NH)BiI

Shijing Sun, Satoshi Tominaka, Jung-Hoon Lee, Fei Xie, Paul D. Bristowe and Anthony K. Cheetham

29th February 2016

Abstract

Organic-inorganic halide perovskites, especially methylammonium lead halide, have recently led to remarkable advances in photovoltaic devices. However, due to environmental and stability concerns around the use of lead, research into lead-free perovskitestructures has been attracting increasing attention. In this study, a layered perovskite-like architecture, (NH)BiI, is prepared from solution and the structure solved by single crystalX-ray diffraction. The band gap, which is estimated to be 2.04 eV using UV-visible spectroscopy, is lower than that of CHNHPbBr. The energy-minimized structure obtained from first principles calculations is in excellent agreement with the X-ray results and establishes the locations of the hydrogen atoms. The calculations also point to a significant lone pair effect on the bismuth ion. Single crystal and powder conductivity measurements are performed to examine the potential application of (NH)BiI as an alternative to the lead containing perovskites.