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Updated: Jan 10, 2026

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films
Published on: September 8, 2017
Synthesis and SHG properties of the melamine-based material (C3N6H7)ZnX3(C3N6H6) (X = Cl, Br)
Melena Groß1, Catharina Darine Brand1, Patrick Schmidt1
1Section of Solid State and Theoretical Inorganic Chemistry, Institute of Inorganic Chemistry, Eberhard Karls University Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany. juergen.meyer@uni-tuebingen.de.
None:
The zinc halide-melamine system was investigated by conducting exploratory solid-state reactions and hydrothermal syntheses, yielding Zn3(OH)2Cl4(C3N6H6)3 and (C3N6H7)ZnX3(C3N6H6) with X = Cl and Br. All compounds were characterized by single-crystal X-ray diffraction, revealing that there are two modifications of the melaminium-zinc-chloride-melamine compound, crystallizing with non-centrosymmetric space groups (Pna21 and P21). The presence of delocalized π-electron systems in compounds containing cyclic (B3O6)3-, (C3N3O3)3-, or melamine derivatives is known to give rise to significant second harmonic generation (SHG) properties, provided that the given structure has no inversion center. All crystal structures feature Zn2+ in a tetrahedral coordination environment, forming layered structures. Spectroscopic measurements on phase-pure orthorhombic (C3N6H7)ZnBr3(C3N6H6) resulted in direct and indirect band gaps of 4.74 eV and 4.46 eV respectively. Measurements of the nonlinear optical response performed on single crystals of three different compounds revealed significant intensities following the sequence monoclinic (C3N6H7)ZnCl3(C3N6H6) > orthorhombic (C3N6H7)ZnBr3(C3N6H6) > orthorhombic (C3N6H7)ZnCl3(C3N6H6). Their SHG properties are compared with those of KTP, one of the most widely used SHG materials.
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