On the importance of ferroelectric domains for the performance of perovskite solar cells

This work analyzes in detail the effect of ferroelectric polarization patterns in methylammonium lead iodide (MAPbI) thin-films on the J-V characteristics of the corresponding solar cells. The simulations are based on a finite-element discretization of the drift-diffusion equations and take into account the polarization pattern experimentally derived from piezoresponse force micrographs. Based on the knowledge of the crystalline structure, symmetry considerations and electrical simulations, we discuss models for the polarization orientation pattern and magnitude of the ferroelectric domains. We conclude that the in-plane polarization vectors have 45° orientation towards the domain walls and form herring-bone structures. The presence of ordered ferroelectric domains, even with a weak characteristic polarization magnitude enhances the power conversion efficiencies and are mandatory to reproduce the experimental J-V characteristics.