Here we report a fully flexible, foldable nanopatterned wearable triboelectric nanogenerator (WTNG) with high power-generating performance and mechanical robustness. Both a silver (Ag)-coated textile and polydimethylsiloxane (PDMS) nanopatterns based on ZnO nanorod arrays on a Ag-coated textile template were used as active triboelectric materials. A high output voltage and current of about 120 V and 65 μA, respectively, were observed from a nanopatterned PDMS-based WTNG, while an output voltage and current of 30 V and 20 μA were obtained by the non-nanopatterned flat PDMS-based WTNG under the same compressive force of 10 kgf. Furthermore, very high voltage and current outputs with an average value of 170 V and 120 μA, respectively, were obtained from a four-layer-stacked WTNG under the same compressive force. Notably it was found there are no significant differences in the output voltages measured from the multilayer-stacked WTNG over 12 000 cycles, confirming the excellent mechanical durability of WTNGs. Finally, we successfully demonstrated the self-powered operation of light-emitting diodes, a liquid crystal display, and a keyless vehicle entry system only with the output power of our WTNG without any help of external power sources.

A highly stretchable hybrid nanogenerator has been developed using a micro-patterned piezoelectric polymer P(VDF-TrFE), PDMS-CNT composite, and graphene nanosheets. Mechanical and thermal energies are simultaneously harvested from a single cell of the device. The hybrid nanogenerator exhibits high robustness behavior even after 30% stretching and generates very stable piezoelectric and pyroelectric power outputs due to micro-pattern designing.

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.

Hydrophobic sponge structure-based triboelectric nanogenerators using an inverse opal structured film for sustainable energy harvesting over a wide range of humid atmosphere have been successfully demonstrated. The output voltage and current density reach a record value of 130 V and 0.10 mA cm(-2) , respectively, giving over 10-fold power enhancement, compared with the flat film-based triboelectric nanogenerator.

Highly stretchable 2D fabrics are prepared by weaving fibers for a fabric-structured triboelectric nanogenerator (FTENG). The fibers mainly consist of Al wires and polydimethylsiloxane (PDMS) tubes with a high-aspect-ratio nanotextured surface with vertically aligned nanowires. The fabrics were produced by interlacing the fibers, which was bonded to a waterproof fabric for all-weather use for fabric-structured triboelectric nanogenerator (FTENG). It showed a stable high-output voltage and current of 40 V and 210 μA, corresponding to an instantaneous power output of 4 mW. The FTENG also exhibits high robustness behavior even after 25% stretching, enough for use in smart clothing applications and other wearable electronics. For wearable applications, the nanogenerator was successfully demonstrated in applications of footstep-driven large-scale power mats during walking and power clothing attached to the elbow.

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.

Precise control of morphologies of one- or two-dimensional nanostructures during growth has not been easy, usually degrading device performance and therefore limiting applications to various advanced nanoscale electronics and optoelectronics. Graphene could be a platform to serve as a substrate for both morphology control and direct use of electrodes due to its ideal monolayer flatness with π electrons. Here, we report that, by using graphene directly as a substrate, vertically well-aligned zinc oxide (ZnO) nanowires and nanowalls were obtained systematically by controlling gold (Au) catalyst thickness and growth time without inflicting significant thermal damage on the graphene layer during thermal chemical vapor deposition of ZnO at high temperature of about 900 °C. We clarify Au nanoparticle positions at graphene-ZnO heterojunctions that are very important in realizing advanced nanoscale electronic and optoelectronic applications of such nanostructures. Further, we demonstrate a piezoelectric nanogenerator that was fabricated from the vertically aligned nanowire-nanowall ZnO hybrid/graphene structure generates a new type of direct current through the specific electron dynamics in the nanowire-nanowall hybrid.

A fully packaged hemispheres‐array‐structured triboelectric nanogenerator (H‐TENG) that can endure severe environments is reported. The hemispheres‐array‐structure plays a dual role as the triboelectric material and an elastic “spring” to keep the two opposite materials separated for inducing the electrostatic effect during contact‐separation cycle. H‐TENGs can be applicable as an active self‐powered sensor array to detect the distribution of external pressure.