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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]

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]

Broadband photodetection has shown a great promise for diverse applications, while the realization of plateau photoresponse from ultraviolet (UV) to near‐infrared (NIR) spectral region is very challenging. Herein, we exploit photoexcited pyroelectric effect in a chiral hybrid perovskite, (N, N‐dimethylcyclohexylammonium)PbBr3 (1), serving as a new pathway to drive broadband photoactivities. It is a room‐temperature pyroelectric with large polarization of ≈6.4 μC cm−2 and high pyroelectric figure‐of‐merits (FV=1.0×10−2 cm2 μC−1 and FD=7.1×10−5 Pa−1/2). Strikingly, light‐induced pyroelectric effect arising from spontaneous polarization is observed in 1, which cover UV (266 nm) to NIR‐II (1950 nm) full spectral region. The broadband photoresponses actualized by pyroelectricity break the limit of optical band gap. As the first demonstration of photo‐pyroelectricity covering UV‐to‐NIR spectral region in hybrid perovskites, this work paves a pathway to assemble high‐performance smart devices. [ABSTRACT FROM AUTHOR]

Polarized‐light detection in the deep ultraviolet solar‐blind region is indispensable for optoelectronic applications. 2D hybrid perovskite ferroelectrics with inherent anisotropy and bulk photovoltaic effect (BPVE) have become a robust candidate in this portfolio. We here report a wide band‐gap 2D perovskite ferroelectric, (isobutylammonium)2(methylamium)Pb2Cl7 (1), in which the BPVE behaves as self‐driving source for solar‐blind ultraviolet polarized‐light detection. It exhibits a large dichroism ratio (≈15.7) and superior BPVE‐directed photocurrent (≈3.6 μA cm−2, under 266 nm). These attributes facilitate excellent self‐powered polarized‐light detection of high on/off contrast (≈103) and polarization ratio (≈2.5), beyond those of inorganic oxides (e.g. ZnO, 1.47; GaN, 1.38). This study highlights potential of 2D perovskite ferroelectrics for new optoelectronic application. [ABSTRACT FROM AUTHOR]