High-Temperature Ferroelasticity and Photoluminescence in a 2D Monolayer Perovskite Compound: (C<sub>5</sub>NH<sub>8</sub>Br)<sub>2</sub>PbBr<sub>4</sub>
Hao Zhang, Qinglian Li, Yu‐Hui Tan, Yun‐Zhi Tang, Xiao‐Wei Fan, Jin-Lin Luo, Fang‐Xin Wang, Ming‐Yang Wan
Abstract
Hybrid organic–inorganic perovskites (HOIPs) have attracted much attention due to their excellent properties and easy synthesis. As far as we know, most documented ferroelastics mainly focus on the 3D (three-dimensional) perovskites, the 2D monolayer perovskite ferroelastics are rarely reported before. In this work, we synthesized a 2D lead-based perovskite (C 5 NH 13 Br) 2 PbBr 4 ( 1 ) (C 5 NH 13 Br = 5-bromoamylamine cation) by introducing flexible chain organic cations. The evolution of ferroelastic domains observed by a polarized light microscope confirms that compound 1 undergoes a ferroelastic phase transition at 392/384 K. In addition, its direct band gap is 2.877 eV. Interestingly, the material emits an attractive blue light (quantum yield 5.06%) under UV light. Three structural descriptors are introduced to quantitatively analyze the relationship between structural distortion and the shape of emission peak. This work provides a way to design multifunctional perovskite-type materials.