Publications by authors named "Han Wool Park"

Ultrahigh-resolution patterning with high-throughput and high-fidelity is highly in demand for expanding the potential of organic light-emitting diodes (OLEDs) from mobile and TV displays into near-to-eye microdisplays. However, current patterning techniques so far suffer from low resolution, consecutive pattern for RGB pixelation, low pattern fidelity, and throughput issue. Here, we present a silicone engineered anisotropic lithography of the organic light-emitting semiconductor (OLES) that in-situ forms a non-volatile etch-blocking layer during reactive ion etching.

View Article and Find Full Text PDF

Rationale: Desmoid fibromatosis is a rare benign tumor, but due to its rarity and diverse clinical course, treatment guidelines have not been established. However, since a good prognosis can be expected, an accurate diagnosis and appropriate treatment are required. We describe a rare case of desmoid fibromatosis on young female that presented as huge abdominal mass.

View Article and Find Full Text PDF

Organic semiconductor (OSC)-based gas detection has attracted considerable attention due to the facile manufacturing process and effective contact with target chemicals at room temperature. However, OSCs intrinsically suffer from inferior sensing and recovery capability due to lack of functional sites and deep gas penetration into the film. Here, we describe an interpenetrating polymer semiconductor nanonetwork (IPSN) channel possessing unreacted silanol (Si-OH) groups on its surface to overcome bottlenecks that come from OSC-based chemodetection.

View Article and Find Full Text PDF

We demonstrate an ionic polymer artificial mechanotransducer (i-PAM) capable of simultaneously yielding an efficient wide bandwidth and a blocking force to maximize human tactile recognition in soft tactile feedback. The unique methodology in the i-PAM relies on an ionic interpenetrating nanofibrillar network that is formed at the interface of (i) an ionic thermoplastic polyurethane nanofibrillar matrix with an ionic liquid of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) and (ii) ionic poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) conducting polymer electrodes with dimethyl sulfoxide and [EMIM][TFSI] as additives. The i-PAM-based actuator with the ionic PEDOT:PSS exhibits a stable operation up to 200 Hz at low voltage as well as a blocking force of 0.

View Article and Find Full Text PDF

A universal method that enables utilization of conventional photolithography for processing a variety of polymer semiconductors is developed. The method relies on imparting chemical and physical orthogonality to a polymer film via formation of a semi-interpenetrating diphasic polymer network with a bridged polysilsesquioxane structure, which is termed an orthogonal polymer semiconductor gel. The synthesized gel films remain tolerant to various chemical and physical etching processes involved in photolithography, thereby facilitating fabrication of high-resolution patterns of polymer semiconductors.

View Article and Find Full Text PDF

We report a novel solvent-free and direct photopatternable poly[(mercaptopropyl)methyl-siloxane] (PMMS) hybrid dielectric for flexible top-gate organic field-effect transistors (OFETs) utilizing a photoactivated thiol-ene reaction under UV irradiation of 254 nm to induce cross-linking, even in air and at low temperatures. In particular, a solvent-free PMMS-f dielectric film, for which an optimal cross-linking density is shown by a well-organized molar ratio between thiol and vinyl in the thiol-ene reaction, exhibited a high dielectric constant (5.4 @ 100 Hz) and a low leakage current (<1 nA mm @ 2 MV cm).

View Article and Find Full Text PDF

Here we demonstrated the split-second crystallization of a liquid-crystalline conjugated polymer semiconductor induced by irradiation with intense pulsed white light (IPWL) for the efficient improvement of electrical properties of flexible thin film transistors. A few seconds of IPWL irradiation of poly(didodecylquaterthiophene-alt-didodecylbithiazole) (PQTBTz-C12) thin films generated heat energy through the photo-thermal effect, leading to the crystallization of PQTBTz-C12 and formation of nodule-like nanostructures. The IPWL-induced crystallization of PQTBTz-C12 resulted in a threefold improvement in the field-effect mobility of thin film transistors compared to as-prepared devices.

View Article and Find Full Text PDF

Synopsis of recent research by authors named "Han Wool Park"

  • - Han Wool Park's recent research primarily focuses on advanced materials and technologies for enhanced organic electronics, with a particular emphasis on organic light-emitting diodes (OLEDs) and organic semiconductors.
  • - His work includes innovative techniques such as silicone engineered anisotropic lithography for high-resolution OLED patterning and interpenetrating polymer semiconductor channels for improved gas detection sensitivity.
  • - Additionally, Park explores the development of multifunctional materials, including flexible dielectric materials for organic field-effect transistors and tactile sensors with enhanced performance, demonstrating significant advancements in the field of smart materials and devices.