Materials with an ultralow density and ultrahigh electromagnetic-interference (EMI)-shielding performance are highly desirable in fields of aerospace, portable electronics, and so on. Theoretical work predicts that 3D carbon nanotube (CNT)/graphene hybrids are one of the most promising lightweight EMI shielding materials, owing to their unique nanostructures and extraordinary electronic properties. Herein, for the first time, a lightweight, flexible, and conductive CNT-multilayered graphene edge plane (MLGEP) core-shell hybrid foam is fabricated using chemical vapor deposition. MLGEPs are seamlessly grown on the CNTs, and the hybrid foam exhibits excellent EMI shielding effectiveness which exceeds 38.4 or 47.5 dB in X-band at 1.6 mm, while the density is merely 0.0058 or 0.0089 g cm , respectively, which far surpasses the best values of reported carbon-based composite materials. The grafted MLGEPs on CNTs can obviously enhance the penetration losses of microwaves in foams, leading to a greatly improved EMI shielding performance. In addition, the CNT-MLGEP hybrids also exhibit a great potential as nano-reinforcements for fabricating high-strength polymer-based composites. The results provide an alternative approach to fully explore the potentials of CNT and graphene, for developing advanced multifunctional materials.
In this work, light-controlled bubble-propelled single-component metal oxide tubular microengines have for the first time been demonstrated. For such a simple single-component TiO2 tubular microengine in H2O2 aqueous solution under UV irradiation, when the inner diameter and length of the tube are regulated, the O2 molecules will nucleate and grow into bubbles preferentially on the inner concave surface rather than on the outer surface, resulting in a vital propulsion of the microengine. More importantly, the motion state and speed can be modulated reversibly, fast (the response time is less than 0.2 s) and wirelessly by adjusting UV irradiation. Consequently, the as-developed TiO2 tubular microengine promises potential challenged applications related to photocatalysis, such as "on-the-fly" photocatalytic degradation of organic pollutes and photocatalytic inactivation of bacteria due to the low cost, single component, and simple structure, as well as the facile fabrication in a large-scale.
It is a tough task to greatly improve the working bandwidth for the traditional flat microwave absorbers because of the restriction of available material parameters. In this work, a simple patterning method is proposed to drastically broaden the absorption bandwidth of a conventional magnetic absorber. As a demonstration, an ultra-broadband microwave absorber with more than 90% absorption in the frequency range of 4–40 GHz is designed and experimentally realized, which has a thin thickness of 3.7 mm and a light weight equivalent to a 2-mm-thick flat absorber. In such a patterned absorber, the broadband strong absorption is mainly originated from the simultaneous incorporation of multiple λ/4 resonances and edge diffraction effects. This work provides a facile route to greatly extend the microwave absorption bandwidth for the currently available absorbing materials.
Instant radical polymerization of sterically stabilized magnetically responsive photonic crystal nonaqueous suspensions under magnetic field can obtain flexible thermochromic free-standing films, which display bright iridescent colors strongly sensitive to temperature with good reversibility and durability.
Non-fullerene electron acceptors (NFAs) are recognized as "rising star" in recent years in the organic solar cells (OSCs) community. In contrast to the traditional fullerene electron acceptors, NFAs promise superior feasibility in molecular design with tunable optoelectronic properties, experiencing unprecedented development in the last 5 years with maximum achievable power conversion efficiencies over 18% are acquired in NFA based OSCs. Nevertheless, the stability of NFAs and their OSCs is still problematic and not well understood, and is regarded as the bottleneck toward the commercialization of NFA based OSCs. In this review, recent advances and current understanding of the stability of NFAs and their corresponding OSCs are presented. Specifically, three key factors, including chemical-, photon-, and thermal-, induced degradations in NFAs are analyzed and summarized, with approaches to enhance the stability suggested. This is followed by the discussion of shelf and operational stability of NFA based OSCs, with highlights of operational stabilities in inert, ambient, indoor, and outdoor conditions. It is envisaged that operational lifetime of over 20 years in real world is achievable via the joint efforts from material design, morphology control, interfacial engineering, and encapsulation technology.
Crystallizable, high-mobility conjugated polymers have been employed as secondary donor materials in ternary polymer solar cells in order to improve device efficiency by broadening their spectral response range and enhancing charge dissociation and transport. Here, contrasting effects of two crystallizable polymers, namely, PffBT4T-2OD and PDPP2TBT, in determining the efficiency improvements in PTB7-Th:PC 71 BM host blends are demonstrated. A notable power conversion efficiency of 11% can be obtained by introducing 10% PffBT4T-2OD (relative to PTB7-Th), while the efficiency of PDPP2TBT-incorporated ternary devices decreases dramatically despite an enhancement in hole mobility and light absorption. Blend morphology studies suggest that both PffBT4T-2OD and PDPP2TBT are well dissolved within the host PTB7-Th phase and facilitate an increased degree of phase separation between polymer and fullerene domains. While negligible charge transfer is determined in binary blends of each polymer mixture, effective energy transfer is identified from PffBT4T-2OD to PTB7-Th that contributes to an improvement in ternary blend device efficiency. In contrast, energy transfer from PTB7-Th to PDPP2TBT worsens the efficiency of the ternary device due to inefficient charge dissociation between PDPP2TBT and PC 71 BM. and acceptors, [1,2] controlling and optimizing the nanoscale morphology, [3][4][5] and via interfacial engineering of the device architectures. [6,7] Power conversation efficiency (PCE) metrics for this technology now stand at 13% for lab-scale single junction and tandem devices. [8,9] Ternary photovoltaic blends, [10][11][12][13][14][15] prepared by incorporating a third component into the donor:acceptor active layer, have emerged as a promising strategy for realizing further improvements in PCE by enhancing device spectral response and charge collection efficiency. This method is favorable as it removes the time-consuming and expensive process of synthesizing new conjugated polymers, in addition to the complicated manufacturing steps that are associated with tandem solar cell fabrication. [16,17] Recent work has shown that semicrystalline conjugated macromolecules or small molecules are effective third components when preparing efficient ternary solar cells. [18][19][20] For example, both the crystallinity and face-on preferential polymer orientation in PTB7-Th:PC 71 BM binary blends can be simultaneously enhanced via the addition of a highly crystalline small molecule p-DTS(FBTTH 2 ) 2 , resulting in a high PCE of 10.5% (a relative improvement of 14%). [21] Elsewhere, the incorporation of Si-PCDTBT into the PTB7:PC 71 BM system can result in high device fill factors (FF; up to 77%) through a significant reduction in charge recombination within the active layer. [22] Although these crystallizable additives can be highly ordered in relatively simple pure and binary systems, their ability to undergo ordering in ternary blends is not always realized. [23] Their exact location within the ternary blend morphology-and the cor...
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