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2D Dion–Jacobson (DJ) perovskites recently have attracted extensive attention for X‐ray detection owing to their structural rigidity and environmental stability. The chemical incorporation of π‐conjugation aromatic spacing cations into DJ phase perovskites will increase the rigidity of cation and electron cloud density between adjacent inorganic slabs, thus facilitating structural rigidity and charge transport. However, it is still a challenge to synthesize high‐quality single crystals of DJ phase perovskite with aromatic spacers for detecting X‐ray applications. Here, a new DJ phase perovskite by introducing π‐conjugated aromatic cation spacer, (4ABA)PbI4 (1, 4ABA = 4‐aminobenzylamine), eliminating the van der Waals gap is designed. High‐quality single crystals of 1 are grown via the facile solution method, exhibiting high resistivity (1.97 × 1011 Ω cm), low trap density (3.36 × 109 cm−3), and large carrier mobility‐lifetime product (1.03 × 10−3 cm2 V−1) under X‐ray illumination. Such remarkable physical characteristics endow single crystal 1 detector with high‐performance X‐ray detection including a high sensitivity of 572 µC Gyair−1cm−2, an ultralow detection limit of 7.50 nGyair s−1 and exceptional radiation stability. The X‐ray detection limit of 1 is over 700 times lower than that of routine medical diagnosis (5500 nGyair s−1), demonstrating potential applications in medical examination. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive materials, showing bistable behaviors between two distinct states under external stimuli, can be potentially applied as basic components of modern electrical and electronic devices. 2D hybrid perovskites hold a promise to switch and tune dielectric bistability based on their solid‐state phase transitions. Here, strong dielectric enhancements are successfully actualized by virtue of light illumination in a Dion–Jacobson (DJ) type 2D hybrid perovskite, (HDA)(MA)2Pb3Br10 (1, where HDA is 1,6‐hexanediammonium and MA is methylammonium). Upon heating, 1 exhibits an ordered–disordered phase transition ≈ 324 K (Tc), accompanying a transition from its low to high dielectric state. Strikingly, its light‐induced dielectric constant changes are greatly enhanced with a magnitude up to 250% near the Tc, superior to most traditional inorganic phase transition materials. This process closely relates to the photoexcited dielectric effect that is caused by the interband photo‐excitation. Benefitting from the stability of DJ‐type perovskite structure, the switching cycles of dielectric enhancement display operational stability with superior anti‐fatigue characteristics. As per the knowledge, the findings of this strong dielectric enhancement are unprecedented in the family of 2D DJ‐type hybrid perovskites, which will facilitate broad interest in exploiting new stimuli‐responsive materials to assemble high‐performance smart electronic devices. [ABSTRACT FROM AUTHOR]

The photopyroelectric effect in ferroelectrics has shown great potential for application in infrared detection and imaging. One particular subclass is broadband with dielectric bistability, which allows for large pyroelectric figures‐of‐merit (FOMs). Herein, an improper high‐Tc perovskite ferroelectric, (IA)2(EA)2Pb3Cl10 (1, where IA is isoamylammonium and EA is ethylammonium) is presented, in which spontaneous polarization (Ps) stems from the dynamic ordering of organic cations and the tilting of distorted PbCl6 octahedra. Notably, 1 displays unusual dielectric bistability with small variations in the temperature‐dependent dielectric constants near Tc = 392 K; this bistable attribute endows large pyroelectric FOMs with peak voltage efficiency (FV = 1.7×10−2 cm2 µC−1) and sensitivity (FD = 3.9×10−4 Pa−1/2). These FV and FD parameters, beyond those of their proper counterparts, make 1 a promising candidate for infrared photodetection. As expected, the broadband photopyroelectric effects observed in 1 covered the ultraviolet to infrared‐II spectral region (266–1950 nm). Such Ps‐directed photoactivities overcome the optical bandgap limitation and allow for wide‐wave photodetection. As an innovative study on improper ferroelectricity, light is shaded here on the targeted engineering of new electrically ordered candidate materials for smart optoelectronic devices. [ABSTRACT FROM AUTHOR]

Layered heterostructures of different 2D building blocks have invigorated the booming of 2D materials toward high‐performance optoelectronic devices. However, contrary to the typical artificial multi‐component form, the engineering of non‐artificial layered heterostructure into single‐phase crystals and resultant properties are largely overlooked. Here, for the first time, an inch‐sized single crystal of a non‐artificial layered heterostructure is exploited, (PbBr2)2(AMTP)2PbBr4 (1, AMTP is 4‐ammoniomethyltetrahydropyran), serving as polarization‐sensitive candidate. Notably, it adopts an interleaved architecture of 2D perovskite slabs with the distinct non‐perovskite lattice, thus forming a self‐assembled perovskite‐intergrowth layered heterostructure. This motif leads to new electronic transitions distributed across two sublattices and affords an inherent in‐plane anisotropy ratio of ≈1.6, beyond some known inorganic materials (e.g., GeSe: 1.44; GeAs: 1.49). Combining this in‐plane anisotropy and wide bandgap (≈2.9 eV), lateral crystal array of 1 enables shortwave polarized‐light detection with ultrahigh responsivity and detectivity under weak illumination compared to some inorganic polarized detectors. As the first demonstration of inch‐sized single crystals of non‐artificial layered heterostructure, this study affords a new platform to explore candidates toward high‐performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

Dion–Jacobson (DJ) phase of 2D hybrid perovskites has recently attracted intensive attention owing to their remarkable optoelectronic properties and superior structural stability. In spite of great endeavors, only a few DJ‐type multilayered hybrid perovskites are obtained and most of them are constructed by very small organic spacer cations (e.g., Cs+ and CH3NH3+). It is still challenging to incorporate larger spacing moieties inside the perovskite cages for accomplishing excellent photoelectric properties. Herein, a newly tailored member of DJ‐type 2D perovskites, (HIS)(DMA)Pb2Br7 (1, where HIS2+ is histammonium and DMA+ is dimethylammonium), of which the perovskite cavities display a remarkable structural distortion to accommodate relatively larger secondary DMA+ cation as the "perovskitizer" is acquired. The monolayers of divalent HIS2+ organic cations directly link to inorganic sheets through NH∙∙∙Br hydrogen bonds, thus eliminating the van der Waals gap in 2D Ruddlesden–Popper counterparts and enabling superior phase stability. As a result, crystal‐based array photodetector of 1 shows fascinating photoactive activities of high detectivity (1.2 × 1013 Jones), large responsivity (18.1 A W−1), and antifatigue behavior, along with polarization‐sensitive detection based on the intrinsic anisotropy. Such findings disclose the potential of 1 for efficient photodetection, and definitely enrich the booming family of 2D hybrid perovskites. [ABSTRACT FROM AUTHOR]

Metal-free antiferroelectric materials are holding a promise for energy storage application, owing to their unique merits of wearability, environmental friendliness, and structure tunability. Despite receiving great interests, metal-free antiferroelectrics are quite limited and it is a challenge to acquire new soft antiferroelectric candidates. Here, we have successfully exploited binary CMBrxI1-x and CMBrxCl1-x solid solution as single crystals (0 ≤ x ≤ 1, where CM is cyclohexylmethylammonium). A molecule-level modification can effectively enhance Curie temperature. Emphatically, the binary CM-chloride salt shows the highest antiferroelectric-to-paraelectric Curie temperature of ~453 K among the known molecular antiferroelectrics. Its characteristic double electrical hysteresis loops provide a large electric polarization up to ~11.4 μC/cm2, which endows notable energy storage behaviors. To our best knowledge, this work provides an effective solid-solution methodology to the targeted design of new metal-free antiferroelectric candidates toward biocompatible energy storage devices. Molecular ferroic materials receive considerable interest in view of field-induced switchable polar/magnetic orders. Here, the authors exploit metal-free antiferroelectrics in molecular solid solutions to assemble high-performance ferroic materials. [ABSTRACT FROM AUTHOR]