Terahertz (THz) waves are nowadays used in a multitude of applications ranging from medicine, telecommunication, security surveillance, to fast sensing and imaging. Along with the most apparent aspects of the potential applications, there is also a flip side of the coin: the effects of unwanted electromagnetic pollution on various elements of the environment. Therefore, an effective shielding of THz radiation, preferably with an appreciable amount of absorption, is one of the milestones for the further development of terahertz technology. This review briefly outlines the main aspects of the area of research in terahertz absorbers, materials used, and their specific applications. Particular attention has been paid to the use of carbon‐based materials as terahertz absorbers, needed to fill the gap between the well‐known components across absorption coefficient 10–100 cm⁻¹ for a refractive index 3–5. An example of such a class of materials is that of the organic or hybrid organic–inorganic polymers whose pyrolysis in an inert atmosphere gives black materials containing a residual free carbon phase. The carbon phase is a random network of covalent bonds in which carbon atoms are mainly in sp² hybridization state. The absorption of THz radiation is strongly dependent on the state of arrangement of C‐sp², the amount of carbon, and the graphitic carbon domain size.

In this work, we have prepared a series of polydimethylsiloxane (PDMS) composites containing various graphene flakes loadings (0.02–2 wt%), and their broadband optical properties are being investigated. We demonstrate the tunability and evolution of transmittance and reflection spectra of the composites in a wide spectral range (0.4–200 μm) as a function of graphene content. Using these data we derive the broadband wavelength-dependent absorption coefficient (α) values. Our results show that α is roughly constant in the visible and IR ranges, and, surprisingly, is approximately one order of magnitude lower in the terahertz regime, suggesting different terahertz radiation scattering mechanism in our composite. Our material could be useful for applications in optical communication, sensing or ultrafast photonics.

Increasing the requirements on telecommunications systems such as the need for higher data rates and connectivity via the Internet of things results in continuously increasing amounts of electromagnetic radiation in ever-higher telecommunications bands (up to terahertz). This can generate unwanted electromagnetic radiation that can affect the operation of electronic devices and human health. Here, we demonstrate that nonconductive and lightweight, graphene-based composites can shield more than 99.99% of the electromagnetic energy in the sub-THz range mainly via absorption. This contrasts with state-of-the-art electromagnetic radiation shielding materials that simply redirect the energy of the radiation from a protected area via conduction-based reflection mechanisms. This shifts the problem of electromagnetic pollution from one place to another. We have demonstrated that the proposed composites can be fabricated by industrial compatible methods and are characterized by specific shielding efficiency values that exceed 30 dB cm³ g⁻¹, which is more than those for typical metals used today. Therefore these materials might help to solve the problem of electromagnetic environmental pollution.

We propose a method for monitoring the large-scale homogeneity of the reduction process of graphene oxide. For this purpose, a Raman mapping technique is employed to probe the evolution of the phonon properties of two different graphene oxide (GO) thin films upon controllable thermal reduction. The reduction of GO is reflected by the upshift of the statistical distribution of the relative intensity ratio of the G and D peaks ( I _D / I _G ) of the Raman spectra and is consistent with the ratio obtained for chemically reduced GO. In addition, the shifts of the position distributions of the main Raman modes ( ω D , ω G ) and their cross-correlation with the I _D / I _G ratio provides evidence of a change of the doping level, demonstrating the influence of reduction processes on GO films.

The majority of industry using high-speed communication systems is shifting towards higher frequencies, namely the terahertz range, to meet demands of more effective data transfer. Due to the rising number of devices working in terahertz range, effective shielding of electromagnetic interference (EMI) is required, and thus the need for novel shielding materials to reduce the electromagnetic pollution. Here, we show a study on optical and electrical properties of a series of ethylene co-butyl acrylate/carbon black (EBA/CB) composites with various CB loading. We investigate the transmittance, reflectance, shielding efficiency, absorption coefficient, refractive index and complex dielectric permittivity of the fabricated composites. Finally, we report a material that exhibits superior shielding efficiency (SE)—80 dB at 0.9 THz (14.44 vol% CB loading, 1 mm thick)—which is one of the highest SE values among non-metallic composite materials reported in the literature thus far. Importantly, 99% of the incoming radiation is absorbed by the material, significantly increasing its applicability. The absorption coefficient (α) reaches ~100 cm⁻¹ for the samples with highest CB loading. The EBA/CB composites can be used as lightweight and flexible shielding packaging materials for electronics, as passive terahertz absorbers or as radiation shields for stealth applications.