self-powered electronics for which novel high-performance materials and low-cost fabrication processes are highly sought. Graphene, which exhibits remarkably high specific surface area, thermal conductivity, current density, transparency, and impermeability, [1] is an ideally suited system for exploring conceptually novel flexible electronics including energy harvesting devices. [2] An easy and scalable approach for graphene preparation is the liquid-phase exfoliation of chemically functionalized graphite, such as graphite oxide or graphite intercalated compounds, which allows the separation of the bulk material into individual atomically thin layers in a liquid medium to produce graphene suspensions. However, there are several issues associated with the films deposited from such suspensions, especially those comprising graphene oxide (GO): they are insulating and need to be converted into reduced graphene oxide (rGO) through harsh chemical or thermal processes, [3] which creates defects in the crystallographic structure of graphene, leading to poor electronic performance. Alternatively, pristine graphite (PG) can be directly exfoliated by various techniques such as ball or three-roll milling, sonication, and high-shear mixing to obtain graphene suspensions. [4,5] Such suspensions are stabilized by using organic solvents, [6] or surfactants to prevent reaggregation of the graphene flakes. [7] In particular, PG exfoliation by highshear mixing leads to a significant improvement in the quality of graphene, when compared with other exfoliation methods, and allows the production of more than 100 L h −1 of defect-free graphene water-based suspension. [5,8] Despite the recent developments in the production of graphene suspensions, the integration of high-quality graphene films obtained from water-based exfoliation of PG in emerging applications, such as flexible electronics, is lagging behind. Specifically, emerging and integrating technologies of water-based exfoliation of PG for haversting human energy that convert mechanical energy into electricity using various effects are still in its infacty, and more research is needed to develop and implement triboelectric nanogenerators (TENGs) as self-charging devices for flexible and wearable electronics. This is due to several issues associated with the deposition Wearable technologies are driving current research efforts to self-powered electronics, for which novel high-performance materials such as graphene and low-cost fabrication processes are highly sought.The integration of highquality graphene films obtained from scalable water processing approaches in emerging applications for flexible and wearable electronics is demonstrated. A novel method for the assembly of shear exfoliated graphene in water, comprising a direct transfer process assisted by evaporation of isopropyl alcohol is developed. It is shown that graphene films can be easily transferred to any target substrate such as paper, flexible polymeric sheets and fibers, glass, and Si substrates. By combining gra...

Time-resolved terahertz spectroscopy has become a common method both for fundamental and applied studies focused on improving the quality of human life. However, the issue of finding materials applicable in these systems is still relevant. One of the appropriate solution is 2D materials. Here, we demonstrate the transmission properties of unique graphene-based structures with iron trichloride FeCl 3 dopant on glass, sapphire and Kapton polyimide film substrates that previously were not investigated in the framework of the above-described problems in near infrared and THz ranges. We also show properties of a thin tungsten disulfide WS 2 film fabricated from liquid crystal solutions transferred to a polyimide and polyethylene terephthalate substrates. The introduction of impurities, the selection of structural dimensions and the use of an appropriate substrate for modified 2D layered materials allow to control the transmission of samples for both the terahertz and infrared ranges, which can be used for creation of effective modulators and components for THz spectroscopy systems. Electronic supplementary material The online version of this article (10.1186/s11671-019-3062-3) contains supplementary material, which is available to authorized users.

The alteration of graphene's electrical properties through chemical functionalization is a necessary process in order for graphene to fulfill its potential as a transparent conducting electrode. In this work, we present a method for the transfer and intercalation of large area (wafer scale) graphene samples to produce highly doped FeCl 3 intercalated Few Layer Graphene (FeCl 3 -FLG). Given its excellent flexibility, transmission, and a sheet resistance, comparable to that of Indium Tin Oxide, FeCl 3 -FLG has potential to replace alternative flexible transparent electrodes as well as compete with rigid transparent electrodes. We assess the effect of functionalization temperature on the degree of intercalation in the large area samples and comparing results to that of 1 cm 2 FeCl 3 -FLG samples. Raman spectroscopy is then used to characterize samples, where we introduce a new figure of merit ( PosG ) by which to assess the degree of intercalation in a sample. This is an average G peak position, weighted by the areas of the constituent peaks, which can then be used to map the charge carrier concentration of the sample. The inhomogeneity of the graphene grown by chemical vapor deposition is found to be one of the limiting factors in producing large area, high quality FeCl 3 -FLG.

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