Recently, great interest has been aroused in flexible/bendable electronic equipment such as rollup displays and wearable devices. As flexible energy conversion and energy storage units with high energy and power density represent indispensable components of flexible electronics, they should be carefully considered. However, it is a great challenge to fabricate flexible/bendable power sources. This is mainly due to the lack of reliable materials that combine both electronically superior conductivity and mechanical flexibility, which also possess high stability in electrochemical environments. In this work, we report a new approach to flexible energy devices. We suggest the use of a flexible electrode based on free-standing graphene paper, to be applied in lithium rechargeable batteries. This is the first report in which graphene paper is adopted as a key element applied in a flexible lithium rechargeable battery. Moreover graphene paper is a functional material, which does not only act as a conducting agent, but also as a current collector. The unique combination of its outstanding properties such as high mechanical strength, large surface area, and superior electrical conductivity make graphene paper, a promising base material for flexible energy storage devices. In essence, we discover that the graphene based flexible electrode exhibits significantly improved performances in electrochemical properties, such as in energy density and power density. Moreover graphene paper has better life cycle compared to non-flexible conventional electrode architecture. Accordingly, we believe that our findings will contribute to the full realization of flexible lithium rechargeable batteries used in bendable electronic equipments.

ZnO nanowires were grown between two Au electrodes on an ${\mathrm{Al}}_2{\mathrm{O}}_3$ -deposited Si wafer. Photoresponse, photoresponse spectrum, and current–voltage $\mathrm{(I–V)}$ studies were performed for the investigation into photoconduction mechanism in these nanowires. The photoresponse of the nanowires under the continuous illumination of light with above- or below-gap energies was slow, which indicates that photocurrent in the nanowires is surface-related rather than bulk-related. The photoresponse spectrum represents the above- and below-gap absorption bands for the photocurrents. The $\mathrm{I–V}$ characteristics under the illumination of the above-gap light are ohmic, but the characteristics under the illumination of the below-gap light are Schottky. This observation indicates that the above-gap light lowers the potential barrier built in the contact between the ZnO nanowires and electrodes, but that the below-gap light does not lower the potential barrier.

ZnO nanorods were grown on ${\mathrm{SiO}}_2/\mathrm{Si}$ substrates by a sol-gel method at low temperatures of around $\text{T=95\hspace{0.05em}°}\mathrm{C}.$ The diameters and the lengths of ZnO nanorods increased at high concentrations of zinc nitrate hexahydrate and methenamine solution. Current–voltage characteristics of the ZnO nanorods network followed a typical nonlinear behavior with significant photoresponse below $\text{λ<400\hspace{0.17em}}\mathrm{nm}$ in air, and the conductance was enhanced in vacuum with negligible photoresponse. In photoluminescence (PL) and photocurrent (PC) spectra, the PL peak ${\mathrm{(\lambda }}_{\mathrm{peak}}\text{=380\hspace{0.17em}}\mathrm{nm}$ and 3.26 eV) did not match the PC edge ${\mathrm{(\lambda }}_{\mathrm{edge}}\text{=400\hspace{0.17em}}\mathrm{nm}$ and 3.1 eV), indicating the nondirect band-gap transition in photocurrent. The origin of the photocurrent was discussed from the point of the influence of the desorption of adsorbed water molecules on the surface or inside the ZnO nanorods.

${\text{BiFeO}}_3$ and ${\text{Bi}}_2{\text{FeMnO}}_6$ films were epitaxially grown on ${\text{SrTiO}}_3$ (001) substrates by pulsed-laser deposition, and their structural, magnetic, magneto-optical and optical properties were measured. In ${\text{Bi}}_2{\text{FeMnO}}_6$, Fe is mainly present in the $3+$ valence state, while Mn shows multivalence states. ${\text{Bi}}_2{\text{FeMnO}}_6$ exhibits low magnetization at room temperature and at 5 K indicating there is no significant $B$-site ordering. The ${\text{BiFeO}}_3$ film shows high optical transparency, while ${\text{Bi}}_2{\text{FeMnO}}_6$ shows high absorption loss in the infrared. Density-functional theory modeling of ${\text{BiFeO}}_3$, ${\text{BiMnO}}_3$ and ${\text{Bi}}_2{\text{FeMnO}}_6$ was carried out by applying the generalized gradient approximation (GGA) and $\text{GGA}+U$ methods. The formation enthalpy of ordered ${\text{Bi}}_2{\text{FeMnO}}_6$ is positive for several crystal symmetries and for ferromagnetic (FM) or antiferromagnetic (AFM) spin structures at 0 K temperature, indicating $B$-site ordering is not favored. The electronic structure calculations are consistent with the electronic and optical properties of these films.

Ultra-definition, large-area displays with three-dimensional visual effects represent megatrend in the current/future display industry. On the hardware level, such a “dream” display requires faster pixel switching and higher driving current, which in turn necessitate thin-film transistors (TFTs) with high mobility. Amorphous oxide semiconductors (AOS) such as In-Ga-Zn-O are poised to enable such TFTs, but the trade-off between device performance and stability under illumination critically limits their usability, which is related to the hampered electron-hole recombination caused by the oxygen vacancies. Here we have improved the illumination stability by substituting oxygen with nitrogen in ZnO, which may deactivate oxygen vacancies by raising valence bands above the defect levels. Indeed, the stability under illumination and electrical bias is superior to that of previous AOS-based TFTs. By achieving both mobility and stability, it is highly expected that the present ZnON TFTs will be extensively deployed in next-generation flat-panel displays.