Graphene field effect transistor sensitized by a layer of semiconductor (sensitizer/GFET) is a device structure that is investigated extensively for ultrasensitive photodetection. Among others, organometallic perovskite semiconductor sensitizer has the advantages of long carrier lifetime and solution processable. A further step to improve the responsivity is to design a structure that can promote electron-hole separation and selective carrier trapping in the sensitizer. Here, the use of a hybrid perovskite-organic bulk heterojunction (BHJ) as the light sensitizer to achieve this goal is demonstrated. Our spectroscopy and device measurements show that the CH 3 NH 3 PbI 3 -PCBM BHJ/GFET device has improved charge separation yield and carrier lifetime as compared to a reference device with a CH 3 NH 3 PbI 3 sensitizer only. The key to these enhancement is the presence of [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM), which acts as charge separation and electron trapping sites, resulting in a 30-fold increase in the photoresponsivity. This work shows that the use of a small amount of electron or hole acceptors in the sensitizer layer can be an effective strategy for improving and tuning the photoresponsivity of sensitizer/GFET photodetectors.

In search of optimal structures for functional materials fabrication, the gyroid (G) structure has emerged as a promising subject of widespread research due to its distinct symmetry, 3D interconnected networks, and inherent chiral helices. In the past two decades, researchers have made great progress fabricating G-structured functional materials (GSFMs) based on G templates discovered both in nature and in the lab. The GSFMs demonstrate extraordinary resonance when interacting with light and matter. The superior properties of GSFMs can be divided into two categories based on the dominant structural properties, namely, dramatic optical performances dominated by short-range symmetry and well-defined texture, and effective matter transport due to long-range 3D interconnections and high integrity. In this review, G templates suitable for fabrication of GSFMs are summarized and classified. State-of-the-art optical applications of GSFMs, including photonic bandgap materials, chiral devices, plasmonic materials, and matamaterials, are systematically discussed. Applications of GSFMs involved in effective electron transport and mass transport, including electronic devices, ultrafiltration, and catalysis, are highlighted. Existing challenges that may hinder the final application of GSFMS together with possible solutions are also presented.

To learn from nature for the rational design of optical devices, the chemical and physical aspects of textures of these natural organisms should be systematically unraveled. Then the basic mechanisms as to how these structural units interact with light must be understood in depth. Finally, whether these morphologies can be fabricated by templating methods, by the current top-down methods, or by selfassembly methods should be well assessed. Up to now, biotemplating methods that take advantage of the physicochemical interactions between organic skeletons and the target solid-state materials are broadly adopted, as they are both cost and time effective. Many natural organisms have been successfully used as biotemplates to fabricate artifi cial photonic materials, including butterfl y wings, [20][21][22][23] beetles, [ 24,25 ] plant leaves, [ 26,27 ] and diatoms. [ 28,29 ] The biotemplating method can not only maintain the morphology of the natural organism, but also mimic the optical functions of the biological species. In addition, a wide range of high-quality photonic nanostructures have been fabricated using top-down methods, such as direct laser writing, photoetching, soft-lithography, and electron beam lithography. [ 10,[30][31][32] Some self-assembly systems can also provide us with novel photonic templates for the fabrication of functional materials, such as the opal structure selfassembled by polymer or silica spheres, [ 33,34 ] and some cubic phases self-assembled in block copolymer systems. [35][36][37] Inspired by natural organisms, researchers have achieved great progress in developing photonic materials in recent years. Many natural species, including birds, [ 3,38,39 ] insects (especially Lepidoptera and beetles), [ 3,[40][41][42][43] plants, [ 44,45 ] and aquatic organisms, [ 29,46 ] have a striking appearance with vivid structural colors originating from elaborate photonic crystals (PCs). PCs are periodic photonic nanostructures at the visible light wavelength scale that can affect the propagation of light. Inspired by these vivid structural colors, optical materials with photonic microstructures and brilliant color have been fabricated with applications in areas covering the cosmetics industry, [ 47 ] textile industry, [ 48 ] printing, [ 49 ] displays, [ 16 ] and security labeling. [ 5 ] As we know, structural colors originate from the interaction of light with various elaborate photonic structures, and are mainly determined by three structural parameters: the refractive index ratio, the volume fraction, and the unit cell size. [ 24 ] For certain optical systems, the photonic structural parameters can be tuned by exerting external fi elds to which the compositions are responsive, such as pH, [ 22,50 ] electromagnetic fi elds, [ 23,51 ] thermal fi elds, [ 52,53 ] gases, [ 54,55 ] and so on. By quantifying the

Surface-enhanced Raman spectroscopy (SERS) is an important tool for the analytical, trace detection of many inorganic and organic materials, especially for materials involved in medical care, food safety and environmental pollution. Numerous efforts have been dedicated to exploring periodic metallic materials with a high density of hotspots. However, for most periodic metallic materials fabricated by top-down and bottom-up approaches, the distribution of hotspots is restricted to one or two dimensions. Here, for the first time, we report the successful fabrication of a bio-inspired bicontinuous gyroid-structured Au SERS substrate with a high density of three-dimensionally (3D) distributed hotspots. The as-required gyroid-structured substrates were demonstrated to be highly sensitive, reproducible and uniform, with an enhancement factor of up to 10 9 . Finite-difference time domain (FDTD) simulations were conducted to reveal the mechanism leading to the high enhancement and we found that the interconnected helices in the gyroid structure not only increase the hotspot density but also contribute to increasing the scattering cross-section of the incident laser. The substrate was then adopted for the SERS detection of bis(2-ethylhexyl) phthalate, the most frequently used plasticizer in food, paints, house-hold items, perfumes and so on, and reached a detection limit of 1 fM, which is among the best results ever reported. Moreover, the mechanism deduced here will provide insight into the future design and selection of novel surface plasmonic resonance substrates, as many other bicontinuous interconnected systems are available. NPG Asia Materials (2018) 10, e462; doi:10.1038/am.2017.230; published online 12 January 2018 INTRODUCTIONThe fabrication of surface plasmonic resonance (SPR) materials with ultra-high plasmonic enhancement has long been a critical research area due to their broad applications as chemical sensors, biological sensors, plasmonic solar cells, photocatalysts and other environmentally friendly devices. 1-3 Among these applications, the most famous is the surface-enhanced Raman spectroscopy (SERS) detection of trace analytes, especially for analytes involved in medical care, food safety and environmental pollution. Various nanoparticle systems with novel nanomorphologies and their assemblies have been fabricated and reported to show excellent SPR performance. 2-5 However, SERS nanostructures composed of nanoparticles face significant challenges in achieving a reproducible and uniform Raman response due to the difficulty in fabricating uniform SERS active sites. Periodic metallic materials could provide hotspots with high density, reproducibility and uniformity, which completely meet the requirement of valid SERS substrates, and therefore numerous efforts have been dedicated to engineering periodic metallic materials with novel nanomorphologies,