Hwa Sung Lee

To investigate the effects of the phase state (ordered or disordered) of self-assembled monolayers (SAMs) on the growth mode of pentacene films and the performance of organic thin-film transistors (OTFTs), we deposited pentacene molecules on SAMs of octadecyltrichlorosilane (ODTS) with different alkyl-chain orientations at various substrate temperatures (30, 60, and 90 degrees C). We found that the SAM phase state played an important role in both cases. Pentacene films grown on relatively highly

Wrinkled elastomeric templates prepared by stretching and releasing are utilized for demonstrating highly sensitive, simple, and low-cost piezocapacitive pressure sensors over large area.

Asterisk-shaped strain sensors have the recognizabilities of stress degree and direction to overcome the shortcomings of existing strain sensors.

Printing technologies are instrumental to the fabrication of low‐cost lightweight flexible electronic devices and circuits, which are necessary to produce wearable electronic applications. However, attaining fully printed devices on flexible films over large areas has typically been a challenge. Here, the fabrication of fully drawn all‐organic field‐effect transistor (FET) arrays on mechanically flexible substrates using a capillary‐pen printing method is demonstrated. A highly crystalline organ

Solution-processed self-patterning of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS_PEN) has been achieved by wettability control on a dielectric surface. This is useful for the fabrication of arrayed patterns due to the exactness and simplicity of the patterns. Especially, we systematically studied the dependence of the self-organization behavior of soluble TIPS_PEN on pattern size and solvent evaporation rate using a circular geometry. With fast evaporation rates during solution-casting,

The alkyl side chain length in poly(3-alkylthiophene) (P3AT) was found to affect the electrical properties and molecular electronic structures in thin films. The self-assembly and morphology of a P3AT film was easily controlled through the solvent vapor pressure (varied over the range 0–55 kPa) during solidification. Under high solvent vapor pressure conditions, long dense nanowires formed in the P3AT thin films, and the electrical properties of field-effect transistors (FETs) based on these fil

We have demonstrated the preparation of interpenetrating polymer network (IPN) dielectrics for use in high-performance organic field-effect transistors by blending commercially available polymers (PMMA, PtBMA, and PS) with the crosslinkable polymeric silsesquiazane (SSQZ). This facile blending method is a powerful means of enhancing the electrical strength of polymer dielectrics due to the formation of a siloxane network structure interspersed among the polymer chains. We found that the leakage

The results show that an intra-articular injection of atelocollagen effectively alleviates knee pain, as intended. Therefore, the intra-articular injection of atelocollagen can be considered an alternative solution to controlling knee pain due to osteoarthritis and diverse cartilage defects.

The introduction of an appropriate functionality on the electrode/active layer interface has been found to be an efficient methodology to enhance the electrical performances of organic field-effect transistors (OFETs). Herein, we efficiently optimized the charge injection/extraction characteristics of source/drain (S/D) electrodes by applying an asymmetric functionalization at each individual electrode/organic semiconductor (OSC) interface. To further clarify the functionalizing effects of the e

Here, we designed and developed an organic field-effect transistor (OFET)-based gas sensor by applying solvatochromic dye (Nile red, NR) with twisted intramolecular charge-transfer (TICT) behavior depending on the polarity of the surrounding molecules, as an auxiliary NR sensing medium (aNR-SM). As a polar molecule approaches, intra-charge transfers from the donor diethylamine group to the ketone group occur in the NR molecule, resulting in the twisting of the donor functional group and thereby

With the emergence of wearable human interface technologies, new applications based on stretchable electronics, such as skin-attached sensors or wearable displays, must be developed. Difficulties associated with developing electronic components with the high stretchabilities required for such applications have restricted the range of appearance and utilization of cost- or process-efficient stretchable electronics. Herein, we present omnidirectionally stretchable wrinkled transistors having a sha

Flexible strain sensors are a key component of electronic skin (e-skin), a technology that is currently receiving considerable research attention with a view to future applications ranging from human healthcare monitoring to robotic skins and environmental risk detection.

The purpose of this study was to explore the early treatment potential of anterior cruciate ligament (ACL) injuries using artificial juxtacrine stimulation by photo-immobilization of a growth factor. A photo-reactive epidermal growth factor complex (EGF-Az) was synthesized by conjugating EGF with N-(4-azidobenzoyloxy) succinimide followed by immobilization onto polystyrene culture plates using UV irradiation. ACL cells from human tissues (1 x 10(5)cells, 100 microl/well) were cultured as follows

Engineering the energy levels of organic conducting materials can be useful for developing high-performance organic field-effect transistors (OFETs), whose electrodes must be well controlled to facilitate easy charge carrier transport from the source to drain through an active channel. However, symmetric source and drain electrodes that have the same energy levels are inevitably unfavorable for either charge injection or charge extraction. In this study, asymmetric source and drain electrodes ar