title: Enhanced Grain Size, Photoluminescence, and Photoconversion Efficiency with Cadmium Addition during the Two-Step Growth of CH3NH3PbI3.
abstract: Control over grain size and crystallinity is important for preparation of methylammonium lead iodide (MAPbI3) solar cells. We explore the effects of using small concentrations of Cd2+and unusually high concentrations of methylammonium iodide during the growth of MAPbI3in the two-step solution process. In addition to improved crystallinity and an enhancement in the size of the grains, time-resolved photoluminescence measurements indicated a dramatic increase in the carrier lifetime. As a result, devices constructed with the Cd-modified perovskites showed nearly a factor of 2 improvement in the power conversion efficiency (PCE) relative to similar devices prepared without Cd addition. The grains also showed a higher degree of orientation in the ⟨110⟩ direction, indicating a change in the growth mechanism, and the films were compact and smooth. We propose a Cd-modified film growth mechanism that invokes a critical role for low-dimensional Cd perovskites to explain the experimental observations.
authors.affiliation: Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States.
authors.forename: Suneth C
authors.identifier: http://orcid.org/0000-0001-8728-9561
authors.initials: SC
authors.lastname: Watthage
authors.affiliation: Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States.
authors.forename: Zhaoning
authors.identifier: http://orcid.org/0000-0002-6677-0994
authors.initials: Z
authors.lastname: Song
authors.affiliation: Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States.
authors.forename: Niraj
authors.initials: N
authors.lastname: Shrestha
authors.affiliation: Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States.
authors.forename: Adam B
authors.initials: AB
authors.lastname: Phillips
authors.affiliation: Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States.
authors.forename: Geethika K
authors.initials: GK
authors.lastname: Liyanage
authors.affiliation: Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Roland
authors.affiliation: Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States.
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Ellingson
authors.affiliation: Wright Center for Photovoltaics Innovation and Commercialization, School of Solar and Advanced Renewable Energy, Department of Physics and Astronomy, University of Toledo , Toledo, Ohio 43606, United States.
authors.forename: Michael J
authors.identifier: http://orcid.org/0000-0002-3788-3471
authors.initials: MJ
authors.lastname: Heben
keywords: cadmium incorporation; carrier lifetime; grain growth; low-dimensional perovskites; nonradiative recombination; perovskite; two-step deposition