Apparent ferroelectric-like and dielectric properties of CH3NH3PbI3 synthesized in ambient air

CH3NH3PbI3 (MAPbI3) has attracted great interest of researchers for its impressively high efficiency in solar cells. Researchers have debated whether or not MAPbI3 is ferroelectric for a long time. In this work, the ferroelectric hysteresis loops, dielectric properties, the real part of impedance and domain structure of the samples synthesized in ambient air (not in a glove box) are investigated. No domain switching current is found in the pellets and films at room temperature, but ferroelectric domains are observed in the films with in plane and out of plane conurations. The dielectric constant as a function of temperature shows that there is no ferroelectric to paraelectric phase transition. The complexity and uncertainty concerning the ferroelectricity of the samples synthesized in ambient air are the same as those synthesized in a glove box.