Wearable electronic devices represent a paradigm change in consumer electronics, on‐body sensing, artificial skins, and wearable communication and entertainment. Because all these electronic devices require energy to operate, wearable energy systems are an integral part of wearable devices. Essentially, the electrodes and other components present in these energy devices should be mechanically strong, flexible, lightweight, and comfortable to the user. Presented here is a critical review of those materials and devices developed for energy conversion and storage applications with an objective to be used in wearable devices. The focus is mainly on the advances made in the field of solar cells, triboelectric generators, Li‐ion batteries, and supercapacitors for wearable device development. As these devices need to be attached/integrated with the fabric, the discussion is limited to devices made in the form of ribbons, filaments, and fibers. Some of the important challenges and future directions to be pursued are also highlighted.

The advancement in high power lasers has urged the requisite of efficient optical limiting materials for both eye and sensor protection. The discovery of atomically thin 2D transition metal dichacogenides with distinctive properties has paved the way for a variety of applications including optical limiting. Until recently, the optical limiting effect exhibited by 2D materials is inferior to the benchmark materials fullerene (C₆₀) and graphene. This article reports the optical limiting activity of the 2D transition metal dichalcogenide, titanium disulfide (TiS₂) nanosheets, using optical and photoacoustic z‐scan techniques. The 77% nonlinear optical limiting exhibited by the TiS₂ sheets with 73% linear‐transmittance is superior to that of any other existing 2D dichalcogenide sheets, graphene, and the benchmark optical limiting material, C₆₀. The enhanced nonlinear response is attributed to the concerted effect of 2‐photon and the induced excited state absorptions. By using photoacoustic z‐scan, a unique tool developed to determine the nonlinear optical limiting mechanism in materials, it is found that the optical limiting exhibited by TiS₂ 2D sheets and graphene are mainly due to nonlinear absorption rather than scattering effects. These results have opened the door for 2D‐dichalcogenide‐materials‐based highly efficient optical limiters, especially at low fluences.

Conducting polyaniline (PANi)–graphene (G) free standing, hybrid films were obtained by a solution intercalation method suitable for electromagnetic interference (EMI) shielding applications. The films were characterized structurally using Fourier transform infrared spectroscopy, micro-Raman spectroscopy, X-ray diffraction and scanning electron microscopy. The electrical characterization was done using Hall measurement setup to estimate the dc electrical conductivity and establish the charge carrier type and mobility and investigate the possibility of using the hybrid films in other applications. The thermal stability of the films was investigated using thermo gravimetric analysis. The EMI shielding effectiveness (SE) of the composite films was tested over a broad microwave frequency range covering 4–12 GHz (C and X bands) by waveguide transmission line technique. The films exhibit very high values of reflected power (P_r) in the range of 85–90% in the C-band and 75–80% in the X-band, respectively. A maximum total shielding effectiveness value of SE_T ∼ 42 dB could be observed in the frequency range of 4–8 GHz and SE_T ∼ 32 dB could be observed in the frequency range of 8–12 GHz, corresponding to more than 99.99% microwave attenuation in both the C and X bands. In the entire frequency range of analysis, contributions from reflection to the total EMI SE is very high compared to that of absorption. The results suggest that the hybrid film may be used as effective, lightweight and flexible, reflection dominated EMI shielding material in a broad range of electromagnetic spectrum.