Circularly polarized light (CPL) detection is required in various fields such as drug screening, security surveillance and quantum optics. Conventionally, CPL photodetector needs the installation of optical elements, imposing difficulties for integrated and flexible devices. The established CPL detectors without optical elements rely on chiral organic semiconductor and metal metamaterials, but they suffer from extremely low responsivity. Organic-inorganic hybrid materials combine CPL-sensitive absorption induced by chiral organics and efficient charge transport of inorganic frameworks, providing an option for direct CPL detection. Here we report the CPL detector using chiral organic-inorganic hybrid perovskites, and obtain a device with responsivity of 797 mA W -1 , detectivity of 7.1 × 10 11 Jones, 3-dB frequency of 150 Hz and one-month stability, a competitive combined feature for circularly polarized light detection. Thanks to the solution processing, we further demonstrate flexible devices on polyethylene terephthalate substrate with comparable performance.
Metal halide perovskite quantum dots (QDs) recently have attracted great research attentions. However, blue-emitting perovskite QDs generally suffer from low photoluminescence quantum yield (PLQY) because of easily formed defects and insufficient surface passivation. Replacement of lead with low toxicity elements is also preferred toward potential commercial applications. Here, we apply Cl-passivation to boost the PLQY of MABiBr QDs to 54.1% at the wavelength of 422 nm, a new PLQY record for blue emissive, lead-free perovskite QDs. Because of the incompatible crystal structures between MABiBr and MABiCl and the careful kinetic control during the synthesis, Cl anions are engineered to mainly locate on the surface of QDs acting as passivating ligands, which effectively suppress surface defects and enhance the PLQY. Our results highlight the potential of MABiBr QDs for applications of phosphors, scintillators, and light-emitting diodes.
Lead halide perovskites have recently shown great potential as X-ray scintillators; however, the toxicity of the lead element seriously restricts their applications. Herein we report a new lead-free and self-absorption-free scintillator based on Rb 2 CuCl 3 metal halide. The Rb 2 CuCl 3 exhibits a near-unity photoluminescence quantum yield (99.4%) as well as a long photoluminescence lifetime (11.3 μs). Furthermore, Rb 2 CuCl 3 demonstrates an appreciable light yield of 16 600 photons per megaelectronvolt and a large scintillation response with a linear range from 48.6 nGy air s −1 to 15.7 μGy air s −1 . Notably, the detection limit is as low as 88.5 nGy air s −1 , enabling a reduced radiation dose to the human body when a medical and security check is conducted. In addition, Rb 2 CuCl 3 exhibits good stability against the atmosphere, continuous ultraviolet light, as well as X-ray irradiation. The combination of the decent scintillation performance, low toxicity and good stability suggests the Rb 2 CuCl 3 could be a possible promising X-ray scintillator.
Lead halide perovskites have shown great X-ray scintillation properties. One big challenge is to find nontoxic replacements for practical applications. Moreover, the scintillator should contain less intrinsic radioactivity as possible to suppress the constant background signal. Here, we report K 2 CuBr 3 with ultralow intrinsic radioactivity. The abundance of radioactive isotope 40 K is 0.0118%, while Cu and Br do not contain stable radioactive isotopes. Thanks to the one-dimensional crystal structure and strong electron−phonon coupling, K 2 CuBr 3 exhibits strong carrier confinement and high photoluminescence quantum yield (86.98%) for the violet emission (peak, 391 nm). Such a high PLQY value is among the highest for all kinds of violet emitters. For X-ray scintillation applications, we evaluate the light yield to be 23,806 photons per MeV, and the detection limit is 132.8 nGy air s −1 .
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