Abstract
Organo-metal halide perovskites can exhibit co-existed electrical polarizations and semiconducting
properties respectively from organic and inorganic components. Here, we find that the Seebeck coefficient
can be changed between positive and negative values when the concentration of chloride ions is
varied between single-halide (CH3NH3PbI3) and mixed-halide structures (CH3NH3PbIxCl3x). This indicates
that varying the concentration of chloride ions can tune the semiconducting properties between
the n-type and p-type regimes in the organo-metal halide perovskites. Our temperature-dependent
capacitance measurement shows that increasing temperature can cause a change on internal electrical
polarization. As a result, we can propose that the internal polarization functions as the underlying
mechanism responsible for large temperature-dependent Seebeck coefficients in organo-metal halide
perovskites operating between n-type and p-type regimes.
