Hysteresis related to ion migration rather than ferroelectric polarization in MAPbI3

Understanding ferroelectric characteristic is crucial, especially for elucidating the existence of ferroelectric and its relationship with hysteresis in hybrid organic–inorganic perovskites. Our focus is to evaluate the ferroelectric properties of MAPbI3 perovskite films by suppressing the rotation of the MA+ ions through the substitution of TMA+ cations. Our findings indicate that both MAPbI3 and MA0.85TMA0.15PbI3 exhibit non-ferroelectric properties at room temperature, which persist even after external polarization treatment. Further analysis reveals that the hysteresis in J–V characteristics is associated with ion migration phenomena. The external polarization treatment aids in releasing electrons from defect states, enabling them to revert to their original lattice sites. As a result, devices subjected to polarization treatment exhibit reduced hysteresis and enhanced photovoltaic performance.