The methylammonium lead halide perovskites have shown significant promise as a low-cost, second generation, photovoltaic material.Despite recent advances, however, there are still a number of fundamental aspects of their formation as well as their physical and electronic behavior that are not well understood. In this letter we explore the mechanism by which these materials crystallize by testing the outcome of each of the reagent halide salts. We find that components of both salts, lead halide and methylammonium halide, are relatively mobile and can be readily exchanged during the crystallization process when the reaction is carried out in solution or in the solid state. We exploit this fact by showing that the perovskite structure is formed even when the lead salt's anion is a non-halide, leading to lower annealing temperature and time requirements for film formation. Studies into these behaviors may ultimately lead to improved processing conditions for photovoltaic films. © 2014 Author(s).
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUS-C1-018-02
Acknowledgements: The authors acknowledge financial support from the National Science Foundation through Materials World Network grants (DMR-1008125 and DMR 1210304). K. W. T. gratefully acknowledges the Singapore Energy Innovation Programme Office for a National Research Foundation graduate fellowship. This work made use of the research facilities of the Cornell Center for Materials Research (CCMR) with support from the NSF Materials Research Science and Engineering Centers (MRSEC) program (DMR-1120296), Cornell High Energy Synchrotron Source (CHESS) which is supported by the NSF and the NIH/National Institute of General Medical Sciences under NSF Award No. DMR-0936384, and the KAUST-Cornell Center for Energy and Sustainability supported by Award No. KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST). The authors gratefully acknowledge Trent Scott of Cornell University for his experimental assistance.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.