The performance of a photovoltaic device is strongly dependent on the light harvesting properties of the absorber layer as well as the charge separation at the donor/acceptor interfaces. Atomically thin two-dimensional transition metal dichalcogenides (2-D TMDCs) exhibit strong light-matter interaction, large optical conductivity, and high electron mobility; thus they can be highly promising materials for next-generation ultrathin solar cells and optoelectronics. However, the short optical absorption path inherent in such atomically thin layers limits practical applications. A heterostructure geometry comprising 2-D TMDCs (e.g., MoS2) and a strongly absorbing material with long electron-hole diffusion lengths such as methylammonium lead halide perovskites (CH3NH3PbI3) may overcome this constraint to some extent, provided the charge transfer at the heterostructure interface is not hampered by their band offsets. Herein, we demonstrate that the intrinsic band offset at the CH3NH3PbI3/MoS2 interface can be overcome by creating sulfur vacancies in MoS2 using a mild plasma treatment; ultrafast hole transfer from CH3NH3PbI3 to MoS2 occurs within 320 fs with 83% efficiency following photoexcitation. Importantly, our work highlights the feasibility of applying defect-engineered 2-D TMDCs as charge-extraction layers in perovskite-based optoelectronic devices.

In this paper, nearly monodispersed urchinlike Ni powders were synthesized by a simple hydrogen-thermal reduction method. Electromagnetic and absorption characteristics were then investigated at 0.5–18 GHz. The permeability spectra present four resonance peaks over the whole frequency range. The resonance absorption property was discussed by fitting the permeability spectrum using the well-known Landau-Lifshitz-Gilbert equation and Maxwell-Garnett mixing rule. Correspondingly, the magnetic loss of the first band observed is attributed to the natural resonance, while the other three bands are considered to originate from non-uniform exchange resonance in the permeability spectra. The maximum reflection loss can reach −43 dB at about 10 GHz with 2 mm in absorber thickness.

Animals such as chameleons possess a natural ability to adjust their skin color as a preventive measure to deter any potential threat and to self-heal damaged skin tissues. Inspired by this, we present here a copolymer film possessing biomimetic properties that simultaneously integrates electrochromic triphenylamine and self-healing Diels-Alder groups. The flexible and stretchable copolymer film acts like natural chameleon skin, which exhibits significant color variation and also possesses excellent self-healing properties. These remarkable features make it a promising material for overcoming the crack-generation issue inherited by conventional biomimetic chameleon skin. Moreover, a flexible and wearable skin device based on the copolymer film with silver fabric as a electrode has also been fabricated. The electrochromic and self-healing properties were verified for the copolymer film, and it has been elucidated that the intelligent biomimetic "chameleon skin" was a new step toward the development of highly advanced biomimetic materials and devices.