Dynamic Disorder Restriction of Methylammonium (MA) Groups in Chloride-Doped MAPbBr3 Hybrid Perovskites: A Neutron Powder Diffraction Study |
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| Authors: | Dr. Carlos Alberto López Dr. María Consuelo Álvarez-Galván Dr. María Victoria Martínez-Huerta Dr. María Teresa Fernández-Díaz Dr. José Antonio Alonso |
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| Affiliation: | 1. Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain;2. Instituto de Catálisis y Petroleoquímica, CSIC, Cantoblanco, 28049 Madrid, Spain;3. Institut Laue Langevin, 38042 Grenoble Cedex, France |
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| Abstract: | The hybrid methylammonium (MA) lead halide MAPbX3 perovskites present an appealing optoelectronic behavior with applications in high-efficiency solar cells. The orientation of the organic MA units may play an important role in the properties, given the degrees of freedom for internal motion of MA groups within the PbX6 network. The present neutron powder diffraction study reveals the dynamic features of the MA units in the hybrid perovskite series MAPb(Br1−xClx)3, with x=0, 0.33, 0.5, 0.67, and 1. From difference Fourier maps, the H and C/N positions were located within the PbX6 lattice; the refinement of the crystal structures unveiled the MA conformations. Three different orientations were found to exist as a function of the chlorine content (x) and, therefore, of the cubic unit-cell size. These conformations are stabilized by H-bond interactions with the halide ions, and were found to agree with those reported from theoretical calculations. |
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| Keywords: | methylammonium lead halides neutron diffraction perovskite phases solar cells |
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