Determination of the miscibility gap in the solid solutions series of methylammonium lead iodide/chloride. Issue 5 (30th August 2018)

• Record Type: Journal Article
• Authors: Franz, Alexandra; Többens, Daniel M.; Steckhan, Julia; Schorr, Susan
• Is Part Of: Acta crystallographica. Volume 74:Issue 5(2018:Oct.)
• Page Start: 445
• Page End: 449
• Publication Date: 2018-08-30
• Subjects: powder diffraction -- hybrid perovskites -- miscibility gap -- MAPbX3
• DOI: 10.1107/S2052520618010764
• Languages: English
• ISSNs: 2052-5206

Abstract

Abstract : The determination of the miscibility gap and of the maximum degree of Cl substitution in the hybrid perovskite solid solution series CH3 NH3 Pb(I, Cl)3, relevant for photovoltaic applications, based on high‐resolution synchrotron powder X‐ray data, is presented Abstract : Perovskites are widely known for their enormous possibility of elemental substitution, which leads to a large variety of physical properties. Hybrid perovskites such as CH3 NH3 PbI3 (MAPbI3 ) and CH3 NH3 PbCl3 (MAPbCl3 ) are perovskites with an A [XII] B [VI] X [II] 3 ‐structure, where A is an organic molecule, B is a lead(II) cation and X is a halide anion of iodine or chlorine. Whereas MAPbCl3 crystallizes in the cubic space group, MAPbI3 is in the tetragonal space group I 4/ mcm . The substitution of I by Cl leads to an increased tolerance against humidity but is challenging or even impossible due to their large difference in ionic radii. Here, the influence of an increasing Cl content in the reaction solution on the miscibility of the solid solution members is examined systematically. Powders were synthesized by two different routes depending on the I:Cl ratio. High‐resolution synchrotron X‐ray data are used to establish values for the limits of the miscibility gap which are 3.1 (1.1) mol% MAPbCl3 in MAPI and 1.0 (1) mol% MAPbI3 in MAPCl. The establishment of relations between average pseudo‐cubic lattice parameters for both phases allows a determination of the degree of substitution from the observed lattice parameters.