メカノケミカル反応によるCsSnBr₃前駆体合成と前駆体から製造した溶融凝固体の電気伝導度

抄録

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 Cs₄SnBr₆ and CsSn₂Br₅. Although main phase of the bulk produced from a melt was CsSnBr₃, small amount impurity, CsSn₂Br₅ was confirmed. From the electrical conductivity (σ_t) measurement, irreversible temperature dependence of σ_t 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, σ_t 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.