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Emerging wearable devices would benefit from integrating ductile photovoltaic light-harvesting power sources. In this work, we report a small-molecule acceptor (SMA), also known as a non–fullerene acceptor (NFA), designed for stretchable organic solar cell (s-OSC) blends with large mechanical compliance and performance. Blends of the organosilane-functionalized SMA BTP-Si4 with the polymer donor PNTB6-Cl achieved a power conversion efficiency (PCE) of >16% and ultimate strain (ε_u) of >95%. Typical SMAs suppress OSC blend ductility, but the addition of BTP-Si4 enhances it. Although BTP-Si4 is less crystalline than other SMAs, it retains considerable electron mobility and is highly miscible with PNTB6-Cl and is essential for enhancing ε_u. Thus,s-OSCs with PCE > 14% and operating normally under various deformations (>80% PCE retention under an 80% strain) were demonstrated. Analysis of several SMA-polymer blends revealed general molecular structure–miscibility–stretchability relationships for designing ductile blends.

 

Hybrid metamaterials (HMs) have attracted significant research interests owing to their unique optical properties and their ability to manipulate light‐matter interaction in a novel and controlled fashion beyond what any single material offers. Especially 3D HMs are of great interest due to their potential to provide advanced and precise control of such light‐matter interaction in nanoscale. In this study, a set of 3D HM nanocomposite films are designed by integrating three phases, i.e., vertically aligned CoFe₂nanosheets within the matrix of TiN/TaN multilayers. By increasing the number of TiN/TaN multilayers from 2 to 19, a high degree of tunability in optical property has been demonstrated, including well‐tailored optical permittivity, and tunable hyperbolic dispersion from Type‐II to Type‐I. Ferromagnetic CoFe₂nanosheets introduces novel magnetic responses, such as magnetic anisotropy and enhanced coercivity. Furthermore, in situ heating X‐ray diffraction (XRD) suggests good thermal stability of the 3D nanocomposite films up to the measured temperature of 600 °C. This three‐phase 3D nanocomposite design offers more flexibility in HM designs, multifunctionalities, and phase stability, compared with the typical two‐phase HMs toward future metamaterials by design.

 

C-axis aligned BaZrO₃(BZO) nanorods formed via strain-mediated self-assembly in BZO-doped YaBa₂Cu₃O_7-x(BZO/YBCO) nanocomposite films can provide strong pinning to the quantized magnetic vortices. While the strain initiated from the BZO/YBCO lattice mismatch plays a critical role in nucleation and evolution of the BZO nanorods, it also leads to a highly defective BZO/YBCO interface and hence reduced pinning efficiency of BZO nanorods. This work reports a recent study in probing the effect of BZO/YBCO interface on the pinning efficiency of the BZO nanorods as the interface is repaired dynamically during the BZO nanorod growth using Ca doping. Within the BZO doping range of 2-8 vol.%, significantly enhanced pinning efficiency of the BZO nanorods have been observed. A peak enhancement up to five-fold of critical current density at 9.0 T and 65-77 K has been obtained in the 6 vol.% BZO/YBCO nanocomposites after the interface repair. This result not only illustrates the critical importance of the BZO/YBCO interface in the pinning efficiency, but also provides a facile scheme to achieve such an interface to restore the pristine pinning efficiency of the BZO nanorods.

 

One-dimensional artificial pinning centers (1D-APCs) in YBa2Cu3O7-x nanocomposite films provide strong collective pinning at magnetic field B//c-axis. In this work, we reveal a 1D-APC/YBa2Cu3O7-x interface is preferred for high pinning efficiency of individual 1D-APCs including BaHfO3 and BaZrO3. The coherent 1D-APC/YBa2Cu3O7-x interface may be obtained via either growth of the nanocomposite films at optimal condition or Ca-diffusion to dynamically reduce the interface strain during the nanocomposite film growth. Interestingly, the high pinning efficiency of the 1D-APCs with coherent interfaces with YBCO not only lead to a high critical current density (Jc) in magnetic fields up to 9.0 T at H//c-axis but also enhanced Jc over a larger angular range when H is away from H//c-axis up to θ=60-80 degree than that in the case the interface is defective. This result suggests the importance of understanding and engineering the APC/YBCO interface for optimal pinning in nanocomposite films. 

High-power electronics, such as GaN high electron mobility transistors (HEMTs), are expected to perform reliably in high-temperature conditions. This study aims to gain an understanding of the microscopic origin of both material and device vulnerabilities to high temperatures by real-time monitoring of the onset of structural degradation under varying temperature conditions. This is achieved by operating GaN HEMT devices in situ inside a transmission electron microscope (TEM). Electron-transparent specimens are prepared from a bulk device and heated up to 800 °C. High-resolution TEM (HRTEM), scanning TEM (STEM), energy-dispersive x-ray spectroscopy (EDS), and geometric phase analysis (GPA) are performed to evaluate crystal quality, material diffusion, and strain propagation in the sample before and after heating. Gate contact area reduction is visible from 470 °C accompanied by Ni/Au intermixing near the gate/AlGaN interface. Elevated temperatures induce significant out-of-plane lattice expansion at the SiNx/GaN/AlGaN interface, as revealed by geometry-phase GPA strain maps, while in-plane strains remain relatively consistent. Exposure to temperatures exceeding 500 °C leads to almost two orders of magnitude increase in leakage current in bulk devices in this study, which complements the results from our TEM experiment. The findings of this study offer real-time visual insights into identifying the initial location of degradation and highlight the impact of temperature on the bulk device’s structure, electrical properties, and material degradation.

 

C–H bond activation enables the facile synthesis of new chemicals. While C–H activation in short-chain alkanes has been widely investigated, it remains largely unexplored for long-chain organic molecules. Here, we report light-driven C–H activation in complex organic materials mediated by 2D transition metal dichalcogenides (TMDCs) and the resultant solid-state synthesis of luminescent carbon dots in a spatially-resolved fashion. We unravel the efficient H adsorption and a lowered energy barrier of C–C coupling mediated by 2D TMDCs to promote C–H activation and carbon dots synthesis. Our results shed light on 2D materials for C–H activation in organic compounds for applications in organic chemistry, environmental remediation, and photonic materials. 

C–H bond activation enables the facile synthesis of new chemicals. While C–H activation in short-chain alkanes has been widely investigated, it remains largely unexplored for long-chain organic molecules. Here, we report light-driven C–H activation in complex organic materials mediated by 2D transition metal dichalcogenides (TMDCs) and the resultant solid-state synthesis of luminescent carbon dots in a spatially-resolved fashion. We unravel the efficient H adsorption and a lowered energy barrier of C–C coupling mediated by 2D TMDCs to promote C–H activation and carbon dots synthesis. Our results shed light on 2D materials for C–H activation in organic compounds for applications in organic chemistry, environmental remediation, and photonic materials.