Cheolmin Park

Block copolymers (BCPs) have received great attention for the past 40 years but only within the past decade have they been seriously considered for nanotechnological applications. Their applicability to nanotechnology stems from the scale of the microdomains and the convenient tunability of size, shape, and periodicity afforded by changing their molecular parameters. The use of the tensorial physical properties of BCPs in such areas as transport, mechanical, electrical, and optical properties wi

Spreading liquid droplets on solid surfaces is a core topic in physical chemistry with significant technological implications. Liquid metals, which are eutectic alloys of constituent metal atoms with low melting temperatures, are practically useful, but difficult to spread on solid surfaces because of their high surface tension. This makes it difficult to use liquid metals as deformable on-board microcircuitry electrodes, despite their intrinsic deformability. In this study, it is discovered tha

Abstract Despite the excellent photoelectronic properties of the all‐inorganic cesium lead iodide (CsPbI 3 ) perovskite, which does not contain volatile and hygroscopic organic components, only a few CsPbI 3 devices are developed mainly owing to the frequent formation of an undesirable yellow δ‐phase at room temperature. Herein, it is demonstrated that a small quantity of poly(ethylene oxide) (PEO) added to the precursor solution effectively inhibits the formation of the yellow δ‐phase during fi

A flexible field-effect transistor with a poly(3-hexylthiophene) (P3HT) active channel and a ferroelectric poly(vinlyidene fluoride-co-trifluoro ethylene) (PVDF-TrFE) insulator exhibits gate-voltage-controllable multilevel non-volatile memory characteristics with highly reliable data retention and endurance.

The development of high-performance printable electrical circuits, particularly based on liquid metals, is fundamental for device interconnection in flexible electronics, motivating numerous attempts to develop a variety of alloys and their composites. Despite their great potential, rewritable and printable electronic circuits based on liquid metals are still manufactured on demand. In this study, we demonstrate liquid metal-based hydrogels suitable for rewritable, printable electrical circuits.

Free-standing and film-type moisture-driven energy generators (MEGs) that harness the preferential interaction of ionized moisture with hydrophilic materials are interesting because of their wearability and portability without needing a water container. However, most such MEGs work in limited humidity conditions, which provide a substantial moisture gradient. Herein, we present a high-performance MEG with sustainable power-production capability in a wide range of environments. The bilayer-based

Tremendous efforts have been devoted to developing thin film halide perovskites (HPs) for use in high-performance photoelectronic devices, including solar cells, displays, and photodetectors. Furthermore, structured HPs with periodic micro- or nanopatterns have recently attracted significant interest due to their potential to not only improve the efficiency of an individual device via the controlled arrangement of HP crystals into a confined geometry, but also to technologically pixelate the dev

Wearable strain sensors have aroused increasing interest in human motion monitoring, even for the detection of small physiological signals such as joint movement and pulse. Stable monitoring of underwater human motion for a long time is still a notable challenge, as electronic devices can lose their effectiveness in a wet environment. In this study, a superhydrophobic and conductive knitted polyester fabric-based strain sensor was fabricated via dip coating of graphene oxide and polydimethylsilo

Abstract Summary: This manuscript describes a new simple method to disperse single wall carbon nanotubes (SWNTs) in various organic solvents. The method is based on using amphiphilic block copolymer micelles as a dispersant. We have found that the stabilization of SWNTs by block copolymer micelles adhering to the surface of nanotubes is much superior to that by either surfactants or high‐molecular‐weight polymers currently used. Our nondestructive method is beneficial because the amphiphilic pro

Abstract Artificial photonic synapses with morphologically controlled photoreception, allowing for area‐dependent tunable light reception as well as information storage and learning, have potential for application in emerging photo‐interactive neuro‐computing technologies. Herein, an artificially intelligent (AI) photonic synapse with area‐density‐tunable perovskite nano‐cone arrays templated in a self‐assembled block copolymer (BCP) is presented, which is based on a field effect transistor with

Abstract Polymer ferroelectric‐gate field effect transistors (Fe‐FETs) employing ferroelectric polymer thin films as gate insulators are highly attractive as a next‐generation non‐volatile memory. Furthermore, polymer Fe‐FETs have been recently of interest owing to their capability of storing data in more than 2 states in a single device, that is, they have multi‐level cell (MLC) operation potential for high density data storage. However, among a variety of technological issues of MLC polymer Fe