title: Chemical Pathways Connecting Lead(II) Iodide and Perovskite via Polymeric Plumbate(II) Fiber.
abstract: Despite tremendous progress in optoelectronic devices using lead perovskite (CH3NH3(+)PbI3(-)), there has been a paucity of mechanistic information on how photoactive micron-sized crystals of lead perovskite grow from a mixture of a layered crystal of lead(II) iodide and methylammonium iodide mediated by a polar solvent, DMSO or DMF. We report here that the whole process of the lead perovskite synthesis consists of a series of equilibria driven by reversible solvent participation involving a polymeric strip of plumbate(II) oligomer as a key intermediate. A significant finding includes quick decomposition of perovskite crystal upon exposure to DMSO or DMF at room temperature, where the solvent molecules act as a base to remove acidic ammonium iodide from the perovskite crystal. This observation accounts for the difficulty in controlling perovskite solar cell fabrication. Overall, the polar solvent is indispensible first to degrade a 2-D sheet of crystals of lead(II) iodide into 1-D fibrous intermediates and then to promote Oswald ripening of perovskite crystals. The detailed chemical information provided here will help to rationalize the photovoltaic device studies that have so far remained empirical and to open a new venue to a developing field of microscale lead perovskite devices, as illustrated by fabrication of photovoltaic devices and photodetectors.
authors.affiliation: Department of Chemistry, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Department of Chemistry, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Shoyama
authors.affiliation: Department of Chemistry, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Sato
authors.affiliation: Department of Chemistry, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Matsuo
authors.affiliation: Department of Chemistry, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Kento
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Department of Chemistry, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Harano
authors.affiliation: Department of Chemistry, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Chao
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Chemistry, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: Department of Chemistry, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Nakamura