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Luminescent ferroelectrics are holding exciting prospect for integrated photoelectronic devices due to potential light‐polarization interactions at electron scale. Integrating ferroelectricity and long‐lived afterglow emission in a single material would offer new possibilities for fundamental research and applications, however, related reports have been a blank to date. For the first time, we here achieved the combination of notable ferroelectricity and afterglow emission in an organic‐inorganic hybrid material. Remarkably, the presented (4‐methylpiperidium)CdCl3 also shows noticeable antiferroelectric behavior. The implementation of cationic customization and halogen engineering not only enables a dramatic enhancement of Curie temperature of 114.4 K but also brings a record longest emission lifetime up to 117.11 ms under ambient conditions, realizing a leapfrog improvement of at least two orders of magnitude compared to reported hybrid ferroelectrics so far. This finding would herald the emergence of novel application potential, such as multi‐level density data storage or multifunctional sensors, towards the future integrated optoelectronic devices with multitasking capabilities. [ABSTRACT FROM AUTHOR]

The ability to generate and manipulate photoluminescence (PL) behavior has been of primary importance for applications in information security. Excavating novel optical effects to create more possibilities for information encoding has become a continuous challenge. Herein, we present an unprecedented PL temporary quenching that highly couples with thermodynamic phase transition in a hybrid crystal (DMML)2MnBr4 (DMML=N,N‐dimethylmorpholinium). Such unusual PL behavior originates from the anomalous variation of [MnBr4]2− tetrahedrons that leads to non‐radiation recombination near the phase transition temperature of 340 K. Remarkably, the suitable detectable temperature, narrow response window, high sensitivity, and good cyclability of this PL temporary quenching will endow encryption applications with high concealment, operational flexibility, durability, and commercial popularization. Profited from these attributes, a fire‐new optical encryption model is devised to demonstrate high confidential information security. This unprecedented optical effect would provide new insights and paradigms for the development of luminescent materials to enlighten future information encryption. [ABSTRACT FROM AUTHOR]

There has been broad exploration of organic–inorganic hybrid perovskite (OIHP) materials in the scientific community because they have shown vigorous vitality and compatibility in the fields of photovoltaics, light-emitting diodes, and intelligent switches. Based on the relationship between structure and property, the internal structure of a material often directly affects its physical and chemical properties, such as electrical and optical performances. OIHPs with one solid–solid phase transition behavior have been widely studied and reported. However, multi-functional OIHPs possessing a two-step dielectric response coupled with photoluminescence properties are rarely reported. Herein, we report two multi-functional hybrid materials, [(BTA)2MnCl2.4Br1.6] (compound 1) and [(BTA)2MnCl4] (compound 2)(BTA = 3-bromopropyltrimethylamonium). Both compounds undergo two sequential structural transitions accompanying remarkably bistable dielectric responses. Moreover, compounds 1 and 2 can emit bright green light under 365 nm with photoluminescence decay lifetimes of 0.153 ms and 0.198 ms, respectively. Notably, the photoluminescence quantum yield of compound 1 is further increased compared with that of compound 2. These two-step reversible dielectric switching materials with photoluminescence properties will provide a new case and guidance for further research and exploration of multifunctional materials that undergo multi-step dielectric switching in the application of sensors. [ABSTRACT FROM AUTHOR]

Hybrid organic‐inorganic perovskite (HOIP) have received tremendous scientific attention because of the phase transition and photovoltaic properties. However, achieving the special perovskite structure with both two‐step dielectric response and luminescence characteristics is rarely reported. Herein, we report an organic‐inorganic hybrid perovskite, [(BA)2 ⋅ PbI4] (Compound 1, BA=n‐butylamine) by introducing flexible organic cations (HBA+), with direct mid‐band gap as 2.28 eV. Interestingly, this material exhibits two‐step reversible dielectric response at 350 K and 460 K (in heating process), respectively. Besides, the photoluminescence was found: it emits charming green light under 365 nm lamp (Photoluminescence quantum yield is 9.52 %). The outstanding two‐step dielectric response and luminescence characteristics of this compound might pave the way for the application of dielectric and ferroelectric functional materials in temperature sensors and mechanical switches. [ABSTRACT FROM AUTHOR]

A bistable optical–electrical duple switch belongs to a class of highly satisfying intelligent materials that can transform optical and electrical responses simultaneously in one device. A perovskite-type high-temperature phase transition compound with one-dimensional chain-like crystal structure, ([(CH3)3PCH2OCH3][PbBr3], 1), displays remarkable bistable photoluminescent-dielectric duple switching behaviors. The noteworthy order–disorder transition of the phosphonium cation and the motions of anions contribute to the phase transition, leading to the space group P21/c at a low temperature phase to C2/c at a high temperature phase. 1 exhibits a prominent step-like dielectric anomaly at 401.0 K and demonstrates novel optical properties with a band gap of 3.54 eV. The photoluminescence intensity suddenly declines from 398 K to 408 K, which may be attributed to the occurrence of phase transition. The electron cloud distributions of the frontier orbital in compound 1 have been calculated using a DFT program. [ABSTRACT FROM AUTHOR]

A bistable optical–electrical duple switch belongs to a class of highly satisfying intelligent materials that can transform optical and electrical responses simultaneously in one device. A perovskite-type high-temperature phase transition compound with one-dimensional chain-like crystal structure, ([(CH3)3PCH2OCH3][PbBr3], 1), displays remarkable bistable photoluminescent-dielectric duple switching behaviors. The noteworthy order–disorder transition of the phosphonium cation and the motions of anions contribute to the phase transition, leading to the space group P21/c at a low temperature phase to C2/c at a high temperature phase. 1 exhibits a prominent step-like dielectric anomaly at 401.0 K and demonstrates novel optical properties with a band gap of 3.54 eV. The photoluminescence intensity suddenly declines from 398 K to 408 K, which may be attributed to the occurrence of phase transition. The electron cloud distributions of the frontier orbital in compound 1 have been calculated using a DFT program. [ABSTRACT FROM AUTHOR]