Charge Compensating Defects in Methylammonium Lead Iodide Perovskite Suppressed by Formamidinium Inclusion.

J Phys Chem Lett

Department of Physics and Astronomy, Wright Center for Photovoltaics Innovation and Commercialization , University of Toledo, Toledo , Ohio 43606 , United States.

Published: January 2020


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Article Abstract

Temperature-dependent photoluminescence (PL) spectroscopy measurements have been performed over a range from 9 K to room temperature on polycrystalline methylammonium (MA)/formamidinium (FA) lead iodide (MAFAPbI) perovskite thin films. Our low-temperature PL analysis reveals the existence of charge compensating defects in MAPbI, which may explain the lower net free carrier concentration in MAPbI perovskite. More interestingly, we observe the suppression of the PL emission associated with the charged defects by appropriate FA inclusion. Furthermore, FA incorporation into MAPbI has been found to slow the phase transformation of MAFAPbI from orthorhombic to tetragonal phase, which occurs with increasing temperature. Our analyses of the FA concentration's impact on defect density and structural phase transformation provide beneficial insights that improve the understanding of the photovoltaic properties and application of organic-inorganic metal halide perovskites.

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http://dx.doi.org/10.1021/acs.jpclett.9b03234DOI Listing

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