Production of Solidified Body from a Melt and Its Electrical Conductivity of CsSnBr<sub>3</sub> Using Precursor Prepared by Mechanochemical Reaction Process

Cesium-tin-bromide perovskite (CsSnBr3) has focused on as a candidate material for all-inorganic perovskite solar cell and thermoelectric energy converter because of its optical, electrical, and thermal properties. On the other hand, the electrical properties have not been clarified yet because of several inconsistent reports. In this paper, we produced CsSnBr3 bulk from a melt using the precursor powder prepared by a mechanochemical process. From powder X-ray diffraction analysis, main phase of the precursor was CsSnBr3 perovskite, and minor impurities were Cs2SnBr4 and CsSn2Br5. Although main phase of the bulk produced from a melt was CsSnBr3, small amount impurity, CsSn2Br5 was confirmed. From the electrical conductivity (σt) measurement, irreversible temperature dependence of σt was observed at first time increasing temperature. The conductivity measured from room temperature to 443 K at the first time showed metallic behavior. On the other hand, the temperature dependence is changed into opposite with decreasing temperature. At this operation, σt decrease with decreasing temperature. This semiconductor like behavior was found to be reversible after first increasing temperature operation. These results indicate that post anneal as well as production process of CsSnBr3 would be important to control its electric property.