Kyung Cheol Choi

Organic light-emitting diodes (OLEDs) are established as a mainstream light source for display applications and can now be found in a plethora of consumer electronic devices used daily. This success can be attributed to the rich luminescent properties of organic materials, but efficiency enhancement made over the last few decades has also played a significant role in making OLEDs a practically viable technology. This report summarizes the efforts made so far to improve the external quantum effic

Innovative textile-based washable polymer solar cells are realized by suppressing the hydrolysis of the encapsulation barrier with a SiO₂–polymer composite.

As the demand for flexible, rollable, and foldable displays grows, various state-of-the-art component technologies, including thin-film transistors (TFTs), electrodes, thin-film encapsulations (TFEs), and touch screen panels, have been developed based on organic light-emitting diodes (OLEDs) with flexible organic layers. Developing highly reliable flexible OLEDs is essential to realize flexible displays, but the flexible encapsulation technology still has technical difficulties and issues to be

Abstract Photobiomodulation (PBM) is a safe and noninvasive method that can provide various clinical effects. However, conventional PBM devices using point light sources, such as light‐emitting diodes and lasers have various disadvantages, such as low flexibility, relatively heavy weight, and nonuniform effects. This paper presents a novel wearable PBM patch using a flexible red‐wavelength organic light‐emitting diode (OLED) surface light source, which can be attached to the human body as a pers

Advances in material science and nanotechnology have fostered the miniaturization of devices. Over the past two decades, the form-factor of these devices has evolved from 3D rigid, volumetric devices through 2D film-based flexible electronics, finally to 1D fiber electronics (fibertronics). In this regard, fibertronic strategies toward wearable applications (e.g., electronic textiles (e-textiles)) have attracted considerable attention thanks to their capability to impart various functions into t

Deformable organic light-emitting diode (OLED) based optoelectronic devices hold promise for various wearable applications including biomedical systems and displays, but current OLED technologies require high voltage and lack the power needed for wearable photodynamic therapy (PDT) applications and wearable displays. This paper presents a parallel-stacked OLED (PAOLED) with high power, more than 100 mW/cm², at low voltage (<8 V). The current dispersion ratio can be tuned by optimizing

A fiber-based polymer light-emitting diode (PLED) is demonstrated using dip coating, which is widely used in the textile industry. The fiber PLED shows high luminance (>1000 cd m−2) and low operating voltages (<10 V) and is safely integrated into electronic textiles. This solution process allows for low-cost mass production by roll-to-roll manufacturing. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed

In this study, a dielectric layer/metal/dielectric layer (multilayer) electrode is proposed as both anode and cathode for use in the fabrication of transparent and flexible organic light‐emitting diodes (TFOLEDs). The structure of multilayer electrodes is optimized by systematic experiments and optical calculations considering the transmittance and efficiency of the device. The details of the multilayer electrode structure are [ZnS (24 nm)/Ag (7 nm)/MoO 3 (5 nm)] and [ZnS (3 nm)/Cs 2 CO 3 (1 nm)

Reliable actual fabric-based organic light emitting diodes are demonstrated by adopting polyurethane films, multilayer barriers, and capping layers to ensure long-term stability toward wearable displays. The devices show both operational and shelf-lifetime of over 1000 h. Also, due to the hierarchical structure of the fabrics, the flex stiffness of the fabric substrates is shown to be superior to that of plastic substrates. As a service to our authors and readers, this journal provides supportin

Effective enhancement of the bending characteristics based on FEM analysis was demonstrated after reliable thin film encapsulation of flexible OLEDs.

Abstract Fiber‐based light‐emitting devices, which can be directly integrated into daily clothes, have emerged as a next‐generation display form factor that can provide informational hyper‐connections between humans and devices. However, although various approaches have provided advanced wearability, challenges remain for visualizing information, such as high power consumption resulting from high driving voltage and low current efficiency (CE), limited brightness making information difficult to

Recent advanced studies on flexible and stretchable electronic devices and optoelectronics have made possible a variety of soft and more functional electronic devices. With consumer demand for highly functional or free-form displays, high flexibility and stretchability in light-emitting devices are needed. Herein, we developed a unique structure of stretchable substrates with pillar arrays to reduce the stress on the active area of devices when strain is applied. We confirmed the advantages of t

Neonatal jaundice is a very common disease in newborns and can lead to brain damage or death in severe cases. Phototherapy with light-emitting diode (LED) arrays is widely used as the easiest and fastest way to relieve jaundice in newborns, but it has distinct disadvantages such as loss of water in the patient, damage to the retina, and separation from parents. In this paper, a novel light source-based phototherapy for neonatal jaundice is proposed using a textile-based wearable organic light-em