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Note, paper has been accepted, will be published shortly. 

Abstract High power conversion efficiency (PCE) and mechanical robustness are essential for organic solar cells (OSCs) used in wearable electronics. In this paper, we report a polymerized small molecular acceptor, PNH, achieved by incorporating hydrogen-bonding (H-bonding) urea flexible spacers (FS) into a Y5-OD-like polymer backbone. Fourier transform infrared spectroscopy corroborates the formation of strong H-bonding (N-H···O=C) between the carbonyl unit in the donor polymer PBDB-T and the amine group in PNH, as well as within the PNH acceptors. Furthermore, a control Y5-OD polymer (PCO) incorporating a carbonate FS unit, thus incapable of H-bonding with PBDB-T was investigated. Notably, the PBDB-T:PNH blend achieved a power conversion efficiency (PCE) of 12.1% outperforming the PBDB-T:PCO device (10.8%). This improved PCE is attributed to the enhanced molecular aggregation and charge transport induced by H-bonding interactions. Moreover, the introduction of H-bonding via FS incorporation effectively dissipates the strain energy under mechanical deformations. Thus, blend films exhibit an improved crack-onset strain from 12.16% (PBDB-T:PNH) to 18.02% (PBDB-T:PCO). Importantly, intrinsically stretchable OSCs (is-OSCs) based on the PBDB-T:PNH blend retain 70% of its initial PCE under a 25% strain. Our results highlight the role of incorporating H-bonding FS into the PSMA backbone to enhance both PCE and mechanical stretchability. 

Abstract 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. 

Abstract 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.