The existence and impact of persistent ferroelectric domains in MAPbI3

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Lauren M. Garten1,*, David T. Moore1, Sanjini U. Nanayakkara1, Shyam Dwaraknath2, Philip Schulz1,3, Jake Wands4, Angus Rockett4, Brian Newell5, Kristin A. Persson2,6, Susan Trolier-McKinstry7 and David S. Ginley1,*
1National Renewable Energy Laboratory, Golden, CO 80401, USA.
2Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720, USA.
3CNRS, Institut Photovoltaïque d’Île de France, UMR 9006, 30 route départementale 128, Palaiseau 91120, France.
4Colorado School of Mines, Golden, CO 80401, USA.
5Colorado State University, Fort Collins, CO 80523, USA.
6University of California, Berkeley, Berkeley, CA 94704, USA.
7The Pennsylvania State University, University Park, PA 16802, USA.

↵*Corresponding author. Email: david.ginley@nrel.gov (D.S.G.); lmg356@gmail.com (L.M.G.)
Science Advances 25 Jan 2019:
Vol. 5, no. 1, eaas9311
DOI: 10.1126/sciadv.aas9311

Abstract

Methylammonium lead iodide (MAPbI3) exhibits exceptional photovoltaic performance, but there remains substantial controversy over the existence and impact of ferroelectricity on the photovoltaic response. We confirm ferroelectricity in MAPbI3 single crystals and demonstrate mediation of the electronic response by ferroelectric domain engineering. The ferroelectric response sharply declines above 57°C, consistent with the tetragonal-to-cubic phase transition. Concurrent band excitation piezoresponse force microscopy–contact Kelvin probe force microscopy shows that the measured response is not dominated by spurious electrostatic interactions. Large signal poling (>16 V/cm) orients the permanent polarization into large domains, which show stabilization over weeks. X-ray photoemission spectroscopy results indicate a shift of 400 meV in the binding energy of the iodine core level peaks upon poling, which is reflected in the carrier concentration results from scanning microwave impedance microscopy. The ability to control the ferroelectric response provides routes to increase device stability and photovoltaic performance through domain engineering.