title: Temperature-Dependent Electric Field Poling Effects in CH3NH3PbI3Optoelectronic Devices.
abstract: Organo-lead halide perovskites show excellent optoelectronic properties; however, the unexpected inconsistency in forward-backward I-V characteristics remains a problem for fabricating solar panels. Here we have investigated the reasons behind this "hysteresis" by following the changes in photocurrent and photoluminescence under electric field poling in transverse CH3NH3PbI3-based devices from 300 to 10 K. We found that the hysteresis disappears at cryogenic temperatures, indicating the "freeze-out" of the ionic diffusion contribution. When the same device is cooled under continuous poling, the built-in electric field from ion accumulation brings significant photovoltaic effect even at 10 K. From the change of photoluminescence upon polling, we found a second dipole-related mechanism which enhances radiative recombination upon the alignment of the organic cations. The ionic origin of hysteresis was also verified by applying a magnetic field to affect the ion diffusion. These findings reveal the coexistence of ionic and dipole-related mechanisms for the hysteresis in hybrid perovskites.
authors.affiliation: Department of Physics and Astronomy, University of Utah , Salt Lake City, Utah 84112, United States.
authors.forename: Chuang
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Physics, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Dali
authors.initials: D
authors.lastname: Sun
authors.affiliation: Department of Physics and Astronomy, University of Utah , Salt Lake City, Utah 84112, United States.
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Physics and Astronomy, University of Utah , Salt Lake City, Utah 84112, United States.
authors.forename: Chuan-Xiang
authors.initials: CX
authors.lastname: Sheng
authors.affiliation: Department of Physics and Astronomy, University of Utah , Salt Lake City, Utah 84112, United States.
authors.forename: Zeev Valy
authors.identifier: http://orcid.org/0000-0002-2298-398X
authors.initials: ZV
authors.lastname: Vardeny