Search

Organic–inorganic hybrid metal halides are widely used in X‐ray detection and imaging due to their high X‐ray absorption efficiency, ease of synthesis, and efficient luminescence. However, the issue of lead toxicity remains a concern. In this study, non‐toxic, 0D 2,2′‐(Ethylenedioxy)bis(ethylamine) manganese (II) bromide (EDBEMnBr4) is synthesized using the simple mechanical grinding method and the solution method that exhibits intense green emission at ≈525 nm. Moreover, the change of structure under the influence of temperature and water significantly affects its fluorescence color under UV light. Scintillator materials with and without moisture exposure showed spatial resolutions of 7 and 4 lp mm−1, and low detection limits of 4.62 and 5.25 µGyair s−1, respectively, meeting medical industry standards (<5.5 µGyair s−1). Furthermore, based on the apparent change in luminescence color triggered by moisture for EDBEMnBr4, a preliminary attempt is made to apply it to humidity monitoring showing that the boundary of color change has a good linear dependence on humidity and time. This work provides new opportunities for Mn‐based metal halides in both X‐ray detection as well as moisture detection. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) Ruddlesden–Popper (RP) CsPbI3 perovskite possesses superior phase stability by introducing steric hindrance. However, due to the quantum and dielectric confinement effect, 2D structures usually exhibit large exciton binding energy, and the charge tunneling barrier across the organic interlayer is difficult to eliminate, resulting in poor charge transport and performance. Here, a multiple‐ring aromatic ammonium, 1‐naphthylamine (1‐NA) spacer is developed for 2D RP CsPbI3 perovskite solar cell (PSC). Theoretical simulations and experimental characterizations demonstrate that the 2D RP CsPbI3 perovskite using 1‐NA spacer with extended π‐conjugation lengths reduces the exciton binding energy and facilitates the efficient separation of excitons. In addition, its cations have a significant contribution to the conduction band, which can reduce the bandgap, promote electronic coupling between organic and inorganic layers, and improve interlayer charge transport. Importantly, the strong π–π conjugation of 1‐NA spacer can enhance intermolecular interactions and hydrogen bonding, and prepare high‐quality films with preferred vertical orientation, resulting in lower defect density, and directional charge transport. As a result, the (1‐NA)2(Cs)3Pb4I13 PSC exhibits a record 16.62% performance with enhanced stability. This work provides an efficient approach to improve charge transport and device performance by developing multiple‐ring aromatic spacers. [ABSTRACT FROM AUTHOR]

Zero‐dimensional Cs3Cu2Cl5 exhibits intriguing optical properties, which can meet the basic requirements of ideal scintillator application. Here, green emitter Cs3Cu2Cl5 nanosheets are successfully synthesized, and by doping with 2% potassium (K+), their photoluminescence quantum yield (70.23% to 81.39%), radioluminescence intensity, and stability are improved. Further experimental and theoretical studies point out that: (1) K+ brings the neighboring [Cu2Cl5]3− dimers groups closer, leading to lattice shrinkage and lower lattice constants; (2) such compact crystal structure results in stronger exciton–photon coupling and reduced phonon–electron coupling strength, which is beneficial to form self‐trapped excitons and enhanced luminescence; (3) lower lattice constants also induce decreased bandgap (2.58 to 2.51 eV) and increased Stokes shift (217 to 223 nm), for less self‐absorption and higher quantum efficiency. Finally, area‐controllable uniform flexible Cs3Cu2Cl5:2%K+–polystyrene film is successfully achieved with excellent X‐ray sensibility. Such flexible film shows low cost (2.8223 $/g), broadband response (20–160 keV), and high spatial resolution (5 lp mm−1) that is comparable to commercial CsI:Tl wafer. Moreover, it fits well with nonplanar surfaces for high‐quality medical and industrial flexible images applications. It is believed that this work can provide a viable tactic to enhance X‐ray detection in metal halide scintillators. [ABSTRACT FROM AUTHOR]