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Luminescent solar concentrators (LSCs) have the advantages of translucency, color tunability, wide incident light angles, and high weak light sensitivity, so they are attractive for practical applications. Reducing the reabsorption loss and increasing the photoluminescence quantum yield (PLQY) are effective strategies to improve the efficiency of LSCs. However, materials possessing small reabsorption and high PLQY simultaneously are rare. In this work, we demonstrate a strategy to overcome the reabsorption obstacle by the Stokes shift synergistic engineering of active materials. For the first time, we designed and synthesized three new quasi-2D perovskite/PVDF composite films by a room temperature solution processing method. The composite films are able to combine energy-funneling and a positive transient Stark shift to achieve a high PLQY and large Stokes shift. The composite films exhibit high water stability and improved ultraviolet (UV) stability. The large area LSC device with a size of 10 × 10 cm2 exhibits a remarkable external optical efficiency (ηext) of up to 4.9%, which is the highest value reported among organic–inorganic hybrid perovskite LSCs. This work demonstrates that the Stokes shift synergistic engineering of quasi-2D perovskite/PVDF composites is an ideal strategy for constructing efficient and stable LSC devices. [ABSTRACT FROM AUTHOR]

The compelling demand for laser protection both for civil and defense use calls for new‐generation nonlinear optical materials. Chemical vapor deposition (CVD) techniques provide extra tricks to modulate crystal optical nonlinearity through fractal growth. The synthesized 2D NbSe2 and its fractal structures exhibit giant, broadband laser attenuation behaviors extending into the near Infrared (NIR) range. Particularly, the optical limiting performance generally correlates with the fractal dimension, where Fractal NbSe2 demonstrates enhanced third‐order optical nonlinearity at a huge nonlinear absorption coefficient of 9.7 × 10−4 m W−1 and an ultralow starting threshold of 5 mJ cm−2 at 532 nm. Various techniques include femtosecond spectroscopy, Density functional theory (DFT) calculation and Kelvin probe force microscopy disclose the origin of the strong nonlinearity of the 2D NbSe2 crystals, and suggest the formation of edge states and overall faster carrier dynamics, larger surface contact potential difference NbSe2 fractals contribute to their even augmented nonlinear responses. Fractal engineering thus opens new avenues to fabricate highly efficient laser protection materials, and the blocking of intense beam (a large attenuation factor over 13.3 dB at 532 nm) while allowing transmission of weak one (a high linear optical transmittance over 80%) fulfills the much desired "smart" defense. [ABSTRACT FROM AUTHOR]

Employing naturally abundant bio-materials in fabrication of electronic devices is promising for the development of an eco-friendly community. Herein, we report that tea polyphenols (TPs) can be used as small molecule active materials for the fabrication of flexible bio-memristors. The good water solubility of TPs enables simple solution deposition of a uniform Ag+ doped TP layer, while the pyrogallol and catechol groups in TPs can reduce Ag+ into Ag nanoparticles that facilitate the growth of conductive filaments. The TP-based memristor exhibited reversible volatile switching characteristics associated with the ion diffusive dynamics in the dielectric layer, and simulated synaptic plasticity and integrate-and-fire properties of neurons. Moreover, we successfully obtained flexible memristors, which exhibited good resistive switching properties under mechanical pressure and could operate as artificial neurons. This work paves a promising way for developing eco-friendly and biocompatible wearable neuromorphic computing systems using sustainable natural materials. [ABSTRACT FROM AUTHOR]

Fully non-fused ring acceptor (NFRA) materials have higher structural diversity than their fused ring counterparts, which have the potential to further promote the performance of organic solar cells and reduce the materials cost. However, owing to their non-fused structural nature, it is difficult for NFRAs to achieve the desirable fully planar state during film formation, which ultimately impedes the device performance. To date, the lack of efficient control over the molecular conformation in both solution and solid states remains a major challenge in the material design of NFRAs. Here, we propose a novel "belt" strategy for construction of a high performance NFRA, which is based on installing a bulky cyclic side chain for more efficient tailoring of the molecular conformation. The molecule with a cyclic "belt" (CSO4TIC) shows a more desirable 3D network packing structure and conformation stability as compared with the molecule with conventional linear side chains (LSO4TIC). Notably, the device based on CSO4TIC achieved a power conversion efficiency of 14.22%, placing it among the top efficiencies reported to date for NFRAs. It is believed that this is the pioneering instance of incorporating a cyclic "belt" into NFRA materials, providing a new route towards low cost and high performance organic photovoltaic materials design. [ABSTRACT FROM AUTHOR]

Chiral molecules play important roles in advanced materials and technologies owing to their unique chiroptical properties. How to design and construct the best chiral molecules with intrinsically strong chiroptical properties is still a great challenge since there is an intrinsic contradiction between the large absorption dissymmetry factor and oscillator strength. In this work, through a systematic theoretical investigation, it is found that chiral cylindrical molecules could overcome this problem through accumulating the electric and magnetic transition dipole moment along the cylindrical axis direction while canceling them in other directions. Among all the investigated structures, (M)‐[8]CC2,8 is found to exhibit the best chiroptical properties with gabs of 0.71 and oscillator strength of 0.032. To the best of our knowledge, this is the best chiral molecule with both large dissymmetry factor and oscillator strength. Further increasing the repeating units, the gabs can even reach the theoretical limit of 2 for (M)‐[28]CC2,8, together with a large oscillator strength of 0.134. The result offers the exciting opportunities for designing and synthesizing chiral materials with truly large intrinsically chiroptical properties toward real applications in chiroptoelectronic and chiro‐spintronic devices. [ABSTRACT FROM AUTHOR]

Chiral hybrid organic–inorganic metal halides have attracted wide attention owing to their superior chiroptoelectronic and chirospintronic properties. Here, a new class of chiral lead‐free metal halides, (R/S‐MBA)3Ru2Br9 (MBA = methylbenzylammonium), with unique magnetic properties is reported. (R/S‐MBA)3Ru2Br9 is composed of a surface‐shared octahedron dimer separated by chiral cations and crystallizes into the Sohncke space group of P212121. The crystal structures, chiroptical, magnetic properties, and magnetic circular dichroism of (R/S‐MBA)3Ru2Br9 are systematically investigated. Owing to the strong antiferromagnetic coupling between the Ru atom through bromine bridge in the [Ru2Br9]3− dimer and the weak ferromagnetic coupling between the neighboring [Ru2Br9]3− dimer, (R/S‐MBA)3Ru2Br9 exhibits antiferromagnetic property with Néel temperature at 7 K. Considering the unique magnetic property of ruthenium, together with the rapid progress of antiferromagnetic spintronics and optospintronics recently, this work provides a novel multifunctional lead‐free chiral magnetic candidate toward chiral optoelectronics and antiferromagnetic spintronics. [ABSTRACT FROM AUTHOR]