Hierarchical yolk-shell nanostructure (NiO/Ni/GN@Air@NiO/Ni/GN) derived from Ni-based metal-organic frameworks (Ni-MOFs) is synthesized by solvothermal reactions. After successive carbonization and oxidation treatments, hierarchical NiO/Ni nanocrystals covered with a graphene shell are obtained with the yolk-shell nanostructure intact. The NiO/Ni/GN@Air@NiO/Ni/GN composites are characterized by X-ray diffraction, scanning electron microscopy, and transmission electron micro scopy. The results indicate that the NiO/Ni/GN@Air@NiO/Ni/GN composites exhibit superior electromagnetic wave absorption properties. A minimum reflection loss (RL min ) of −34.5 dB is obtained at 17.2 GHz with the thin thickness of 1.7 mm. In addition, the best microwave absorption properties are achieved with a 2.0 mm absorber layer (RL min = −22.5 dB, bandwidth of 6.0 GHz). The outstanding absorption ability may arise from the unique yolk-shell structure and nanoporous carbon, which can tune the dielectric of the NiO/Ni/GN@Air@NiO/Ni/GN composites to acquire good impedance matching. Moreover, the interspaces can induce interfacial polarization and multiple reflections. Microwave Absorbers

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Various cathode interface materials have been used in organic solar cells (OSCs) to realize high performance. However, most cathode interface materials have their respective weaknesses in maximizing the efficiency or stability of OSCs. Herein, three kinds of alcohol-soluble cathode interfacial materials are combined with bathocuproine (BCP) to serve as multifunctional bilayer cathode buffers for the regular OSCs, and thus greatly enhanced power conversion efficiencies over 10.11% and significantly improved device stability have been achieved. By utilizing double interlayers, both light absorption and light distribution in active layer are improved. Furthermore, double interlayers offer favorable energy-level alignment, alcohol treatment, and duplicate protection of active layer, resulting in significantly reduced leakage current, suppressed recombination, and efficient charge collection. The improved device stability is related to the blocking effect of the complex formed between BCP and the metal electrode and the additional protection effect of the underlying alcohol-soluble materials. In view of the universal use of alcohol-soluble organic electrolyte as cathode buffer layers and by courtesy of the superiority of the double cathode layers relative to the monolayer controls, the double interlayer strategy demonstrated here opens a new way to fully exploiting the potential of OSCs and is believed to be extended to a wider application.

as methylammonium and formamidinium), resulting in the relatively poor long-term stability of PSCs. For another, Au electrodes and organic hole transport layers such as 2,2′,7,7′-Tetrakis(N,N-di-pmethoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) commonly used in organic-inorganic hybrid PSCs are expensive, which weakens the cost advantage of devices. Aiming at these problems, hole transport layer-free, all-inorganic carbonbased PSCs (C-PSCs) with a device structure of fluorine-doped tin oxide (FTO) or tin-doped indium oxide (ITO)/electron transport layer (ETL)/inorganic perovskite/carbon, would be a potential alternative to achieve low cost, high-efficiency, and high stability, simultaneously. [3][4][5][6][7][8][9][10] Among many inorganic perovskites, CsPbI 3 perovskite has the greatest application potential due to its ideal band gap (≈1.70 eV). [11][12][13][14][15][16][17] To pursue highly efficient and stable CsPbI 3 C-PSCs, developing stable and high-quality CsPbI 3 perovskite film with fewer defects is a prerequisite. Xiang et al. discovered air-stable CsPbI 3 film can be obtained by one-step solution deposition method using HPbI 3 instead of PbI 2 , and a PCE of 9.5% was achieved for CsPbI 3 C-PSCs by employing such perovskite film. [18] Then, by doping Natrium in the CsPbI 3 lattice, they further boosted the PCE of CsPbI 3 C-PSCs to 10.7%. [19] Liang et al. boosted the PCE of CsPbI 3 C-PSCs to 12.04% by developing CsPbI 3 :Br:InI 3 , which possesses the same bandgap as CsPbI 3 but has significantly reduced defect density. [20] Wang et al. systematically studied the crystallization of CsPbI 3 films after dimethylammonium iodide (DMAI) treatment, which boosts the efficiency of CsPbI 3 C-PSCs to 14.6%. [21] Recently, Wang et al. adopted the CsPbI 3 film post-processing strategy to form the energy level gradient and generate a 2D Cs 2 PbI 2 Cl 2 nanosheets structure as the electronic blocking layer, which boosts the efficiency of CsPbI 3 C-PSCs to 15.23%. [22] Even though many efforts have been made to achieve high-quality CsPbI 3 films as well as efficient CsPbI 3 C-PSCs, the relatively poor crystallinity is accompanied by many defects of CsPbI 3 film is still the main obstacle for further boosting the PCE of CsPbI 3 C-PSCs.Hole transport layer-free, carbon-based, all-inorganic CsPbI 3 perovskite solar cells (PSCs) have exhibited great potential in photovoltaic applications owing to their low cost and excellent thermal stability. However, the low power conversion efficiency (PCE) hampers its development, mainly due to the existence of defects inside the CsPbI 3 film or at TiO 2 electron transport layer/CsPbI 3 interface. Herein, these issues were addressed through a facile TiO 2 post-treatment strategy using 1-butyl-3-methylimidazole hexafluorophosphate (BMIMPF 6 ) ionic liquid. First, BMIMPF 6 can passivate TiO 2 /CsPbI 3 interface defects by forming strong bond between the electron-rich N atoms and uncoordinated ions. Second, BMIMPF 6 -modified TiO 2 shows reduced hydrophilicity, inducing decreased he...

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A fluorescence inhibitor 1-bromo-4-nitrobenzene was introduced into the PTB7-Th:PC71BM active layer to prepare an organic solar cell that exhibited a high PCE of 8.95%.

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All-polymer solar cells (all-PSCs) have been intensively investigated due to their excellent thermal and mechanical stabilities. However, the efficiency of all-PSCs is still far behind that of organic solar cells (OSCs), which are based on small molecule acceptors. Improving the efficiency of all-PSCs is of great urgency. In this work, the solvent additive named p-anisaldehyde (AA) was introduced to improve the performance of all-PSCs based on PBDB-T:N2200. It is demonstrated that AA helps to form a better network interpenetrating track and more uniform phase separation. With the assistance of AA, which has both an oleophilic methoxy group and a hydrophilic aldehyde group, the interfacial contact between the donor and the acceptor (D/A) is improved, increasing the contact area at D/A and promoting efficient exciton dissociation. More importantly, AA acts as a “bridge” between the oleophilic active layer and the hydrophilic PEDOT:PSS layer, improving the interfacial compatibility between the active layer and the PEDOT:PSS layer, reducing the interfacial resistance, and facilitating the carrier transport. Finally, the all-PSCs based on PBDB-T:N2200 exhibits a superior power conversion efficiency (PCE) of 7.24% which is a record efficiency for the current all-PSCs with the same architecture. In this work, a promising and effective strategy for achieving high efficiency all-PSCs is provided.