Electrical conductivity of CuSnI3, CuPbI3 and KPbI3

Experimental evidence from differential scanning calorimetry, X-ray diffraction and ac and dc electrical conductivity measurements is presented to show that melt-grown CuSnI3 and CuPbI3 samples have hexagonal structure, while KPbI3 has a tetragonal structure at room temperature. It is also shown that other phases of CuPbI3 and KPbI3 exist at high temperature. All samples exhibit conductive properties which are suggestive of anionic vacancy diffusion. The measured room temperature conductivities are 1.11×10−5, 7.1×10−8 and 2.62×10−9 (Ω cm) for CuSnI3, CuPbI3 and KPbI3 respectively. Several interpretations of the results are suggested.