Dielectric Studies on CH3NH3PbX3(X = Cl and Br) Single Cystals

Dielectric dispersion measurements have been performed on CH 3 NH 3 PbX 3 (MAPbX 3 , X = Cl and Br) single crystals at frequencies between 50 Hz and 1 MHz. Significant dielectric dispersion was observed in the cubic and tetragonal II phases for MAPbCl 3 and in the cubic, tetragonal I and tetragonal II phases for MAPbBr 3 . The apparent dielectric dispersion was attributed to the ionic conductivity in the crystals. The static bulk conductivity was expressed by the Arrhenius-type formula σ= ( A / T ) exp (-Δ E / k T ). The activation energies for the ionic conduction along [100] axis for each phase are estimated to be 0.13 eV (cubic phase) for MAPbCl 3 and 0.132 eV (cubic phase) and 1.60 eV (tetragonal I phase) for MAPbBr 3 .