• Hoffmann, Michael J.
• Leonhard, Tobias
• Röhm, Holger
• Schulz, Alexander Deniz
• Colsmann, Alexander
• Wagner, Susanne

Abstract

Whether or not methylammonium lead iodide (MAPbI3) is a ferroelectricsemiconductor has caused controversy in the literature, fueled by manymisunderstandings and imprecise definitions. Correlating recent literaturereports and generic crystal properties with the authors’ experimentalevidence, the authors show that MAPbI3 thin-films are indeed semiconductingferroelectrics and exhibit spontaneous polarization upon transition from thecubic high-temperature phase to the tetragonal phase at room temperature.The polarization is predominantly oriented in-plane and is organized incharacteristic domains as probed with piezoresponse force microscopy.Drift-diffusion simulations based on experimental patterns of polarizeddomains indicate a reduction of the Shockley–Read–Hall recombination ofcharge carriers within the perovskite grains due to the ferroelectric built-in fieldand allow reproduction of the electrical solar cell properties.

Topics

• perovskite
• impedance spectroscopy
• grain
• phase
• thin film
• simulation
• semiconductor
• microscopy