A new hybrid lead(II) halide perovskite, (TzH)₂PbCl₄, ([TzH⁺] = 1,2,4-triazolium), adopts a (001)-oriented layered perovskite structure, which can be considered as derived from the n = 1 Ruddlesden–Popper (RP) type. Variable temperature single crystal X-ray diffraction reveals a structural phase transition in the region 125 K < T < 173 K between a high temperature, high symmetry polymorph, space group Cmcm, and a low temperature, low symmetry chiral polymorph, space group P2₁2₁2₁, which has a tripled unit cell volume. UV-Vis spectra suggest a band gap of 3.30 eV for (TzH)₂PbCl₄. A second polymorph of the bromide analogue, (TzH)₂PbBr₄-II, is also reported, and structural relationships between all three variants are discussed.

中文翻译：

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以（1,2），4-三唑鎓为模板的（001）取向层状卤化铅钙钛矿中的结构变化

一种新的杂化铅（II）卤化物钙钛矿（TzH）₂ PbCl ₄（[[TzH ⁺ ] = 1,2,4-三唑鎓））采用（001）取向的层状钙钛矿结构，可以认为是由所述ñ = 1 Ruddlesden-波普（RP）的类型。可变温度单晶X射线衍射显示在高温高对称多晶型空间群Cmcm和低温低对称手性多晶型空间群P 2之间的125 K < T <173 K区域中结构相变₁ 2 ₁ 2 ₁，其单位细胞体积增加了三倍。UV-Vis光谱表明（TzH）₂ PbCl ₄的带隙为3.30 eV 。还报道了溴化物类似物的第二个多晶型物（TzH）₂ PbBr ₄ -II，并讨论了所有三个变体之间的结构关系。