Incorporating Guanidinium as Perovskitizer-Cation of Two-Dimensional Metal Halide for Crystal-Array Photodetectors

Thermal/Water-Induced Phase Transformation and Photoluminescence of Hybrid Manganese(II)-Based Chloride Single Crystals

Mn(II)-based hybrid halides have attracted great attention from the optoelectronic fields due to their nontoxicity, special luminescent properties, and structural diversity. Here, two novel organic-inorganic hybrid Mn(II)-based halide single crystals (1-mpip)MnCl4·3H2O and (1-mpip)2MnCl6 (1-mpip = 1-methylpiperazinium, C5H14N2+) were grown by a slow evaporation method in ambient atmosphere. Interestingly, (1-mpip)2MnCl6 single crystals exhibit the green emission with a PL peak at 522 nm and photoluminescence quantum yields (PLQYs) of ≈5.4%, whereas (1-mpip)MnCl4·3H2O single crystals exhibit no emission characteristics. More importantly, there exists a thermal-induced phase transformation from (1-mpip)MnCl4·3H2O to emissive (1-mpip)2MnCl6 at 372 K. Moreover, a reversible luminescent conversion between (1-mpip)MnCl4·3H2O and (1-mpip)2MnCl6 was simply achieved when heated to 383 K and placed in a humid environment or sprayed with water. This work not only deepens the understanding of the thermal-induced phase transformation and humidity-sensitive luminescent conversion of hybrid Mn(II)-based halides, but also provides a guidance for thermal and humidity sensing and anticounterfeiting applications of these hybrid materials.

Chlorine Substitution in Spirocyclic Derivatives Triggers SHG Response in Noncentrosymmetric Crystal

Organic-inorganic hybrid phase transition materials with switchable properties have important potential applications in smart devices such as dielectric switches and storage. Nevertheless, it remains challenging to modify molecular structures efficiently to obtain materials simultaneously possessing multiple responsive properties. Herein, different from ordinary halogen substitutions in Metal Halide, we report a halogen regulation design of organic molecular strategy: (ASD) 2 MnBr 4 (ASD=5-azonia-spiro [4.5] decane) to (CASD) 2 MnBr 4 (CASD=8-chloro-5-azonia-spiro [4.5] decane). After organic molecular halogen regulation, the SHG response was excited and the dielectric phase transition temperature ( T c ) has also been greatly improved. Furthermore, under the irradiation of UV lamp, both showed green light with quantum yields above 50%. This work is of great significance for further exploration of multifunctional molecular switch materials through halogen modification strategies.

A bilayered two-dimensional hybrid perovskite with a cage-templated secondary cation for high efficiency photodetection

A novel two-dimensional hybrid perovskite (IA)2(DMA)Pb2Br7 was obtained by introducing a large secondary cation DMA+ into the PbBr6 framework. A highly efficient array photodetector has been assembled using its crystal.

2D Hybrid perovskite incorporating cage-confined secondary ammonium cations toward effective photodetection

By confining the secondary dimethylammonium (DMA) cation in a distorted perovskite cavity, we assembled a new 2D Ruddlesden-Popper metal halide perovskite of (i-BA)₂(DMA)Pb₂Br₇ (i-BA = n-isobutylammonium), in which the DMA cation templates its inorganic perovskite framework and the quantum-well motif renders a fascinating photoresponse. Crystal-based planar arrays exhibit effective photodetection behaviors, including a notable detectivity (∼5.6 × 10¹² Jones), a high responsivity (∼1.25 A W^-1) and a large switching ratio (∼1.5 × 10³). These properties result from its low dark current restricted to the hopping barrier of the insulated organic bilayer and a strong in-plane photoresponse correlated with the perovskite network. This work throws light on the targeted exploration of photosensitive candidates in the family of organic-inorganic hybrid perovskites, as well as high-performance devices.