Transport, optical, and magnetic properties of the conducting halide perovskite ch₃nh₃sni₃

A low-temperature (T ≤ 100°C) solution technique is described for the preparation of polycrystalline and single crystal samples of the conducting halide perovskite, CH3NH3SnI3. Transport, Hall effect, magnetic, and optical properties are examined over the temperature range 1.8-300 K, confirming that this unusual conducting halide perovskite is a low carrier density p-type metal with a Hall hole density, 1/RHe ≃ 2 × 1019 cm-3. The resistivity of pressed pellet samples decreases with decreasing temperature with resistivity ratio ρ(300 K)/ρ(2 K) ≃ 3 and room temperature resistivity ρ(300 K) ≃ 7 mΩ-cm. A free-carrier infrared reflectivity spectrum with a plasma edge observed at approximately 1600 cm-1 further attests to the metallic nature of this compound and suggests a small optical effective mass, m* ≃ 0.2. © 1995 Academic Press.