Duck-Hyun Choi

Serious climate changes and energy-related environmental problems are currently critical issues in the world. In order to reduce carbon emissions and save our environment, renewable energy harvesting technologies will serve as a key solution in the near future. Among them, triboelectric nanogenerators (TENGs), which is one of the most promising mechanical energy harvesters by means of contact electrification phenomenon, are explosively developing due to abundant wasting mechanical energy sources

Fully rollable transparent nanogenerators have been developed using chemical vapor deposition-grown large-scale graphene sheets as transparent electrodes and piezoelectric ZnO-nanorod arrays. The electrical and structural stability of the nanogenerators with excellent charge scavenging performance under external mechanical loads such as bending and rolling shows that graphene-based nanogenerators are suitable for self-powered rollable transparent device applications. Detailed facts of importance

Enhancing the output power of a nanogenerator is essential in applications as a sustainable power source for wireless sensors and microelectronics. We report here a novel approach that greatly enhances piezoelectric power generation by introducing a p-type polymer layer on a piezoelectric semiconducting thin film. Holes at the film surface greatly reduce the piezoelectric potential screening effect caused by free electrons in a piezoelectric semiconducting material. Furthermore, additional carri

Non-lithographic fabrication of a self-aligned nanopore SERS array with large-area hexagonal symmetry is achieved by Au deposition on an anodized aluminum oxide (AAO) template. Precise self-formation of plasmonic nanopore arrays with facile structural tunability allows control of the SERS response, and results in highly reproducible, uniform, and sensitive SERS with an enhancement factor of 107. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such do

The abundance of water on earth provides a large window to utilize the mechanical energy within river currents and ocean waves. In this regard, hydropower harvesting through solid-liquid contact electrification has received considerable interest in the recent past. Despite advancements in nanotechnology, liquid energy harvesting devices, especially solid-liquid triboelectric nanogenerators (S-L TENGs), require efficient engineering of the interfacial properties of their substrates to transfer li

Abstract A mechanosensitive, visco‐poroelastic polymer ion pump that can rapidly establish a dense electrical double layer via mechanical pressure, thereby significantly enhancing output performance of an ionic triboelectric nanogenerator (iTENG), is described. A working mechanism of an iTENG using a highly mechanosensitive, visco‐poroelastic ion pump is suggested and the optimal characteristics of the polymer ion pump are reported by investigating optical, mechanical, electrical, and electroche

Abstract In this work, we demonstrate the mode transition of charge generation between direct‐current (DC) and alternating‐current (AC) from transparent flexible (TF) piezoelectric nanogenerators (NGs), which is dependent solely on the morphology of zinc oxide (ZnO) nanorods without any use of an AC/DC converter. Tilted ZnO nanorods grown on a relatively low‐density seed layer generate DC‐type piezoelectric charges under a pushing load, whereas vertically aligned ZnO nanorods on a relatively hig

A dramatic increase in the power conversion efficiency (PCE) of inverted organic solar cells (IOSCs) is realized by a gallium (Ga)-doped zinc oxide (GZO) buffer layer acting as an electron-transport layer. The GZO nanostructured thin-film buffer layer was synthesized via an aqueous solution method at 90 °C. Both an increase of electrical conductivity and a smooth surface morphology were realized by Ga doping. The PCE of a GZO-based IOSC was improved by about 110% at simulated air mass 1.5 global

Self-powered triboelectric microfluidic system was developed for the simple and rapid liquid sensing with multiple methods such as triboelectric signal and resistance measurement.

Layer-by-layer multilayers are demonstrated for low-cost, durable, scalable, and wearable graphene-TENGs on flat or undulated polymer substrates and fabric textiles.