Ensuring nuclear safety has become of great significance as nuclear power is playing an increasingly important role in supplying worldwide electricity. β-ray monitoring is a crucial method, but commercial organic scintillators for β-ray detection suffer from high temperature failure and irradiation damage. Here, we report a type of β-ray scintillator with good thermotolerance and irradiation hardness based on a two-dimensional halide perovskite. Comprehensive composition engineering and doping are carried out with the rationale elaborated. Consequently, effective β-ray scintillation is obtained, the scintillator shows satisfactory thermal quenching and high decomposition temperature, no functionality decay or hysteresis is observed after an accumulated radiation dose of 10 kGy (dose rate 0.67 kGy h −1). Besides, the two-dimensional halide perovskite β-ray scintillator also overcomes the notorious intrinsic water instability, and benefits from low-cost aqueous synthesis along with superior waterproofness, thus paving the way towards practical application.

Recently, lead halide perovskite (PVSK) polycrystalline films have drawn much attention as photoactive material and scored tremendous achievements in solar cells, photodetectors, light‐emitting diodes, and lasers owing to their engrossing optoelectronic properties and facile solution‐processed fabrication. However, large amounts of grain boundaries unfavorably induce ion migration, surface defect, and poor stability, impeding PVSK polycrystalline film‐based optoelectronic devices from practical application. In comparison with the polycrystalline counterparts, PVSK single crystals (SCs) with lower trap density serve as a better platform for not only fundamental research but also device applications. In light of this, the idea of using PVSK single crystals (SCs) to construct the optoelectronic devices is then proposed. Since then, a series of synthesis methods of PVSK SCs have emerged. In this review, recent progress of synthesis method of PVSK SCs is tried to be summarized and their advantages and limitations are analyzed. And then, the optoelectronic properties including carrier dynamic, defects, ion migration, and instability issues in these 3D and 2D PVSK SCs are overviewed and accordingly the proper device configurations of corresponding solar cells, photodetectors, X‐ray, γ‐ray detectors, etc., are proposed. It is believed that this review can provide the guidance for the further development of PVSK SCs and their applications.

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.201905362. Fluorescence imaging with photodetectors (PDs) toward near-infrared I (NIR-I) photons (700-900 nm), the so-called "optical window" in organisms, has provided an important path for tracing biological processes in vivo. With both excitation photons and fluorescence photons in this narrow range, a stringent requirement arises that the fluorescence signal should be efficiently differentiated for effective sensing, which cannot be fulfilled by common PDs with a broadband response such as Si-based PDs. In this work, delicate optical microcavities are designed to develop a series of bionic PDs with selective response to NIR-I photons, the merits of a narrowband response with a full width at half maximum (FWHM) of <50 nm, and tunability to cover the NIR-I range are highlighted. Inorganic halide perovskite CsPb 0.5 Sn 0.5 I 3 is chosen as the photoactive layer with comprehensive bandgap and film engineering. As a result, these bionic PDs offer a signal/ noise ratio of ≈10 6 , a large bandwidth of 543 kHz and an ultralow detection limit of 0.33 nW. Meanwhile, the peak responsivity (R) and detectivity (D*) reach up to 270 mA W −1 and 5.4 × 10 14 Jones, respectively. Finally, proof-ofconcept NIR-I imaging using the PDs is demonstrated to show great promise in real-life application.Near-infrared photodetectors (NIR PDs) toward distinct photon signal from 700-900 nm (NIR-I) have attracted much attention in the past decades due to their tremendous potential in medical instruments. [1] Benefitting from merits including low

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Photodetectors selective to the polarization empower breakthroughs in sensing technology for target identification. However, the realization of polarization‐sensitive photodetectors based on intrinsically anisotropic crystal structure or extrinsically anisotropic device pattern requires complicated epitaxy and etching processes, which limit scalable production and application. Here, solution‐processed PEA2MA4(Sn0.5Pb0.5)5I16 (PEA= phenylethylammonium, MA= methylammonium) polycrystalline film is probed as photoactive layer toward sensing polarized photon from 300 to 1050 nm. The growth of the PEA2MA4(Sn0.5Pb0.5)5I16 crystal occurs in confined crystallographic orientation of the (202) facet upon the assistance of NH4SCN and NH4Cl, enhancing anisotropic photoelectric properties. Therefore, the photodetector achieves a polarization ratio of 0.41 and dichroism ratio (Imax/Imin) of 2.4 at 900 nm. At 520 nm, the Imax/Imin even surpasses the one of the perovskite crystalline films, 1.8 and ≈1.2, respectively. It is worth noting that the superior figure‐of‐merits possess a response width of 900 kHz, Ion/Ioff ratio of ≈3 × 108, linear dynamic range from 0.15 nW to 12 mW, noise current of 8.28 × 10−13 A × Hz−0.5, and specific detectivity of 1.53 × 1012 Jones, which demonstrate high resolution and high speed for weak signal sensing and imaging. The proof of concept in polarized imaging confirms that the polarization‐sensitive photodetector meets the requirements for practical application in target recognition.