The domination of ionic conductivity in tetragonal phase of the organometal halide perovskite CH3NH3PbI3-xClx

Organometal trihalide perovskites have recently gained extreme attention due to their high solar energy conversion in photovoltaic cells. Here, we investigate the contribution of iodide ions to a total conductivity of the mixed lead halide perovskite CH3NH3PbI3-xClx with a use of the modified DC Hebb-Wagner polarization method. It has been identified that an ionic conductivity dominates in tetragonal phase which is associated with room temperature. The obtained activation energy for this type of hopping mechanism is equal to (0.87 +/- 0.02) eV, which is in a good agreement with previous literature reports. The high contribution of ionic conductivity at room temperature might be a reason of the observed hysteresis in halide perovskite solar cells.