Transparent flexible graphene triboelectric nanogenerators as new promising applications of chemical vapor deposition‐grown graphene are successfully demonstrated. The work function and friction are decisive factors to understand the difference in output performance depending on the number of layers of graphene. In this work, we were able to power an LCD, LEDs, and an EL display using the electrical power output of the graphene triboelectric nanogenerator without any external energy source.

The extremely stable high-power generation from hybrid piezoelectric nanogenerator (HP-NG) based on a composite of single-crystalline piezoelectric perovskite zinc stannate (ZnSnO 3 ) nanocubes and polydimethylsiloxane without any electrical poling treatment is reported. The HP-NG generates large power output under only vertical compression, while there is negligible power generation with other confi gurations of applied strain, such as bending and folding. This unique high unidirectionality of power generation behavior of the HP-NG provides desirable features for large-area piezoelectric power generation based on vertical mechanical compression such as moving vehicles, railway transport, and human walking. The HP-NGs of ZnSnO 3 nanocubes exhibit high mechanical durability, excellent robustness, and high power-generation performance. A large recordable output voltage of about 20 V and an output current density value of about 1 μ A cm − 2 are successfully achived, using a single cell of HP-NG obtained under rolling of a vehicle tire.

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The effect of substrate surface energy on transcrystalline growth at the interface of a semicrystalline polymer and its effect on interfacial adhesion were investigated for substrates treated with various silane coupling agents. A thin film of isotactic polypropylene (iPP) crystallized on a high surface energy substrate (treated with γ-(aminopropyl)triethoxysilane) was composed entirely of transcrystallites. On the other hand, when the iPP film was crystallized on a low surface energy substrate (treated with perfluorodecyltrichlorosilane), the interface was dominated by spherulites, and only a very thin transcrystalline region (thickness ∼1 µm) was observed. The substrate surface energy was found to exert a significant influence on the crystallinity, density of nuclei, crystal microstructure (e.g., lamellar thickness and crystal orientation), and thickness of the transcrystalline region near the interface. The adhesion energy measured by the asymmetric double cantilever beam (ADCB) test increased strongly (from 1 to 100 J/m 2 ) with surface energy. Examination of the fractured specimens using atomic force microscopy and scanning electron microscopy revealed fibrillation of the iPP induced by the strong interfacial adhesion; this was found to be associated with the breakdown of the fibrils, which is the characteristic fracture mechanism of transcrystallites at the interface in high surface energy samples. At lower surface energies, however, cracking occurs at the boundary between the transcrystallites and the spherulites because of the weak boundary layer near the interface.