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Updated: Jun 2, 2025
Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films
Published on: September 8, 2017
Crystal growth, structural phase transitions and optical gap evolution of FAPb(Br1-xClx)3 hybrid perovskites (FA:
Carlos A López1,2, Oscar Fabelo3, Carmen Abia4,3
1Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049, Madrid, Spain. calopez@unsl.edu.ar.
Abstract:
Chemically tuned organic-inorganic hybrid halide perovskites based on bromide and chloride anions CH(NH2)2Pb(Br1-xClx)3 (CH(NH2)2+: formamidinium ion, FA) have been crystallized and investigated by neutron powder diffraction (NPD), single crystal X-ray diffraction (SCXRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. FAPbBr3 and FAPbCl3 experience successive phase transitions upon cooling, lowering the symmetry from cubic to orthorhombic phases; however, these transitions are not observed for the mixed halide phases, probably due to compositional disorder. The band-gap engineering brought about by the chemical doping of FAPb (Br1-xClx)3 perovskites (x = 0.0, 0.33, 0.5, 0.66 and 1.0) can be controllably tuned: the gap progressively increases with the concentration of Cl- ions from 2.17 to 2.91 eV at room temperature, presenting a nonlinear behavior. This study provides an improved understanding of the structural and optical properties of these appealing hybrid perovskites.
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