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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]

Typically, DMSO and DMF are the two most commonly used co-solvents; however, their boiling points differ greatly and the volatilization rate is not consistent when the film is annealed and crystallized, which leads to the inhomogeneity of the components. Herein, the hydrogen isotope effect (HIE) is produced by introducing N,N-dimethylformamide-d7 (DMF-d7) into the CsPbI3 precursor solution for the first time. The introduction of deuterium affects the intermolecular interaction between the solvent molecules and Pb2+, and ameliorates the undesirable situation of excessive uncoordinated Pb2+ remaining on the surface of the film. As a result, the power conversion efficiency (PCE) of the optimized device reached 18.55%. The characterization of the film structure, morphology, and components demonstrates that the addition of DMF-d7 improves the quality of the film. More importantly, according to the apparent change in the atomic ratios of Cs and Pb (Cs/Pb), we speculate that different film crystallization rates eventually lead to two different crystallization termination surfaces, i.e., with PbI2 or CsI, and illustrate their effects on the properties of the film by ab initio simulations. Overall, this study developed a novel solvent system that provides a promising method for the fabrication of high-quality CsPbI3 films. [ABSTRACT FROM AUTHOR]

The two-dimensional (2D) Ruddlesden-Popper (RP) CsPbI 3 with hydrophobic organic spacers can significantly improve the environmental and phase stability of photovoltaic devices by suppressing ion migration and inducing steric hindrance. However, due to the multiple-quantum-well structure, these spacer cations lead to weak interactions in 2D RP CsPbI 3 , which seriously affect the carrier transport. Here, a novel N-H-group-rich phenylhydrazine spacer, namely, PHA, was developed for 2D RP CsPbI 3 perovskite solar cells (PSCs). A series of characterizations confirm that the 2D perovskites using PHA spacers enhanced the N-H ··· I hydrogen-bonding interaction between the organic spacer cations and the [PbI 6 ] 4- inorganic layer and accelerated the crystallization rate of the perovskite film, which was beneficial to the preparation of high-quality films with preferred vertical orientation, large grain size, and dense morphology. Meanwhile, the trap state density of the as-prepared 2D RP perovskite films is significantly reduced to enable efficient charge carrier transport. As a result, the (PHA) 2 Cs 4 Pb 5 I 16 PSCs achieved a performance of 16.23% with good environmental stability. This work provides a simple organic spacer selection scheme to realize interaction optimization in 2D RP CsPbI 3 to develop efficient and stable PSCs.

The continuous advancement of the Internet of Things (IoT) and photovoltaic technology has promoted the development of indoor photovoltaics (IPVs) that powers wireless devices. Nowadays, the CsPbX 3 perovskite has received widespread attention because of its high power conversion efficiency (PCE) in an indoor environment and suitable band gap for IPVs. In this work, we regulated the thickness of the photoactive layer (to optimize the carrier transport process without affecting indoor absorption) and bromine substitution (to adjust the band gap and improve the quality of the film) to reduce trap-assisted carrier recombination. A CsPbI 2.7 Br 0.3 perovskite cell with excellent performance was obtained, which is superior to c-Si cells in a low-light environment. The optimized device achieved PCE values of 32.69 and 33.11% under a 1000 lux fluorescent lamp and white light-emitting diode (WLED) illumination. The J - V hysteresis of the device is also effectively suppressed. Moreover, it has a steady-state output power of 7.76 μW (0.09 cm 2 , and can be enhanced by enlarging the areas), which can meet the consumption of many small wireless devices. It is worth noting that the optimized device has excellent applicability to be used in a complex indoor environment.