Temperature-Dependent Reversible Optical Properties of Mn-Based Organic–Inorganic Hybrid (C<sub>8</sub>H<sub>20</sub>N)<sub>2</sub>MnCl<sub>4</sub> Metal Halides
Tong Chang, Yarui Dai, Qilin Wei, Xing Xu, Sheng Cao, Bingsuo Zou, Qinglin Zhang, Ruosheng Zeng
Abstract
Organic–inorganic metal halides (OIMHs) have abundant optical properties and potential applications, such as light-emitting diodes, displays, solar cells, and photodetectors. Herein, we report zero-dimensional Mn-based OIMH (C 8 H 20 N) 2 MnCl 4 single crystals synthesized by a simple slow evaporation method, which exhibit intense green emission at 520 nm originating from 4 T 1 – 6 A 1 transition of Mn 2+ ions. Large organic cations in the crystal structure result in the isolated [MnCl 4 ] 2– tetrahedrons, and the closest Mn–Mn distance reaches 9.07 Å, which effectively inhibits the migration of excitation energy between adjacent Mn 2+ emission centers, thus achieving a high quantum yield (∼87%) and a long photoluminescence (PL) lifetime (3.42 ms). The different optical and structural properties at low and high temperatures are revealed by temperature-dependent PL and X-ray diffraction spectra. The PL spectra and lifetimes under the heating and cooling processes indicate that the optical property transitions are reversible at 220/240 K. Our work provides a promising strategy for building multifunctional optoelectronic materials and insights into the understanding convertible photophysical properties from isomers of metal halides.