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In the IoT era, the demand for wearable displays is rapidly growing, catalyzing the advancement of research into textile-based organic light-emitting diodes (OLEDs). This growing interest stems particularly from the inherent flexibility of textile-based OLEDs1,2, allowing for seamless integration into the dynamic and interactive functionalities of cutting-edge wearable technology, alongside their superior electrical performance. The durability and mechanical robustness of these displays, especially under physical stress and deformation, are critical to their practical application and longevity. Thus, understanding and enhancing the mechanical properties of textile-based OLEDs is paramount for their successful integration into wearable technologies. However, many studies assessing the mechanical properties of OLEDs have predominantly relied on simplistic bending test outcomes determined by the radius, often neglecting or insufficiently analyzing the strain exerted on the OLEDs atop textile substrates in relation to curvature of these devices. Existing analyses typically presume pure bending, though such an assumption leads to considerable errors in strain estimations, making such approaches problematic if the goal is practical application in actual wearable display products. To address these limitations, an analytic model that includes a comprehensive energy equation is introduced, considering the stretching energy, bending energy, and shear energy of each layer composing the textile substrate. This holistic approach provides a novel formula specifically designed to calculate the top surface strain of textile substrates. Robust validation of this formula is conducted by comparing its results with strain measurements obtained from digital image correlation (DIC) and finite element analysis (FEA) outcomes from ANSYS across various bending radii (or equivalently, curvatures). The close alignment of the calculated strain values with those derived from DIC and FEA not only underscores the precision of this formula but also highlights its significant potential for enhancing the designs and functionalities of future wearable display technologies under real-world conditions. [ABSTRACT FROM AUTHOR]

Stretchable displays attract significant attention because of their potential applications in wearable electronics, smart textiles, and human-conformable devices. This paper introduces an electrically stable, mechanically ultra-robust, and water-resistant stretchable OLED display (SOLED) mounted on a stress-relief pillar platform. The SOLED is fabricated on a thin, transparent polyethylene terephthalate (PET) film using conventional vacuum evaporation, organic-inorganic hybrid thin film encapsulation (TFE), and a nonselective laser patterning process. This simple and efficient process yields an OLED display with exceptional stretchability, reaching up to 95% strain and outstanding durability, enduring 100,000 stretch-release cycles at 50% strain. Operational lifetime and water-resistant storage lifetime measurements confirm that the TFE provides effective protection even after the nonselective laser patterning process. A 3 × 3 array SOLED display module mounted on a stress-relief pillar platform is successfully implemented, marking the first case of water-resistant display array operation in the field of SOLEDs. This work aims to develop practical stretchable displays by offering a reliable fabrication method and device design for creating mechanically robust and adaptable displays, potentially paving the way for future advances in human-conformable electronics and other innovative applications. [ABSTRACT FROM AUTHOR]

A kerfed pillar platform is proposed for deformable double curvature displays, which is designed for a smooth transition between 2D and complex 3D shapes, like spheres and saddles, while maintaining structural integrity. The kerfs modify flexible substrate into the pillar‐island structure, which enhances substrate compressibility, preventing crumpling during 3D curve transformation. It exemplifies controlled deformation, adhering to the superposition principle, and enabling diverse display configurations. The proposed structure provides a new approach for next‐generation display applied for human‐machine interface and architectural design, advancing dynamic, free‐form displays. [ABSTRACT FROM AUTHOR]

We deposited micro‐scale organic light‐emitting diodes(OLEDs) with a red‐emitting material on an ultrathin organic film and demonstrated a flexible device with a cantilever form factor. This platform satisfied the necessary light irradiation conditions applicable for phototherapeutic applications and also holds potential for biomedical implantable areas such as neurotherapy. [ABSTRACT FROM AUTHOR]

This paper presents a novel monorail‐structure fiber‐based organic light‐emitting diode (MFOLED) with the anode patterned like a monorail to enhance operating reliability. The MFOLED improves the uniformity of layer thickness within the light‐emitting region on cylinder fiber despite using only a thermal evaporation method. The device exhibits outstanding operating lifetime (LT50, 720 h), luminance (59335 cd m−2), and current efficiency (70.89 cd A−1), the highest performances published to date. Additionally, red, green, and blue MFOLEDs are fabricated using the same method and driven by a microcontroller unit to confirm the feasibility of implementing fiber‐based subpixels. Based on these results, this work is expected to establish a new benchmark for fiber‐based OLEDs and contribute to the realization of truly wearable displays. [ABSTRACT FROM AUTHOR]

An island‐bridge structure, which is a stretchable display implementation method that has attracted a lot of attention, has a trade‐off between stretchability and resolution. The proposed stretchable OLED avoids this trade‐off and can satisfy both stretchability and display resolution at the same time. [ABSTRACT FROM AUTHOR]

This study proposes a top‐emitting fiber‐based OLED capable of achieving high resolutions in order to achieve truly wearable displays. Additionally, a water‐resistant fiber‐based OLED that can be produced entirely in a vacuum environment to reduce impurities during the process is demonstrated. [ABSTRACT FROM AUTHOR]

Near‐Infrared organic light emitting diode (NIR OLED) that can be potentially applied to flexible devices and bio/medical applications based on NIR emitter and optical effects are proposed. The proposed NIR OLEDs can freely control the peak wavelength in the NIR region of 720 ~ 760 nm and offer the possibility of finding the optimal point of best photo‐therapeutic effects in the NIR region. [ABSTRACT FROM AUTHOR]

Optoelectronics devices utilizing organic light‐emitting diodes (OLEDs) are emerging as new platforms for healthcare applications. In particular, wearable optoelectronics such as visual stimulus systems offer a distinctive advantage to intervene in and improve sleep disorders. In this study, two improvements are proposed for transparent OLEDs (TrOLEDs) that will be critical for visual applications. First, zinc sulfide with high surface energy and a high refractive index is explored as a seed and capping layer. An ultra‐thin silver cathode of 8 nm is demonstrated to be feasible in TrOLEDs, and luminous transmittance of 91% is achieved. Second, in general, achieving the operational stability of TrOLEDs with high transmittance is challenging due to the vulnerability of thin electrodes. By introducing a doping process to the electron transport layer, a lifetime comparable to that of control OLEDs with thick cathodes (>90%) is secured. Last, a preclinical model using blue light is proposed to modulate sleep patterns. Melanopsin is stimulated at the highest level of sleep desire, reducing non‐rapid eye movement sleep duration in mice by up to 14%. Based on these results, the proposed TrOLEDs are promising candidates for modulating sleep disorders such as insomnia and narcolepsy–cataplexy with the convenience of wearable form factors. [ABSTRACT FROM AUTHOR]

Increasing demand for real-time healthcare monitoring is leading to advances in thin and flexible optoelectronic device-based wearable pulse oximetry. Most previous studies have used OLEDs for this purpose, but did not consider the side effects of broad full-width half-maximum (FWHM) characteristics and single substrates. In this study, we performed SpO2 measurement using a fiber-based quantum-dot pulse oximetry (FQPO) system capable of mass production with a transferable encapsulation technique, and a narrow FWHM of about 30 nm. Based on analyses we determined that uniform angular narrow FWHM-based light sources are important for accurate SpO2 measurements through multi-layer structures and human skin tissues. The FQPO was shown to have improved photoplethysmogram (PPG) signal sensitivity with no waveguide-mode noise signal, as is typically generated when using a single substrate (30–50%). We successfully demonstrate improved SpO2 measurement accuracy as well as all-in-one clothing-type pulse oximetry with FQPO. [ABSTRACT FROM AUTHOR]

Near-infrared organic light-emitting diodes (NIR OLEDs) with heavy metals are regularly reported due to the advantages of their various applications in healthcare services, veil authentication, and night vision displays. For commercial applications, it is necessary to look at radiance capacity (RC) instead of radiance because of power consumption. However, recent papers still reported only simple high radiance performance and do not look at device from the point of view of RC. To overcome this hurdle, we designed Ir(III)-based heteroleptic NIR materials with two types of auxiliary ligand. The proposed emitters achieve a highly oriented horizontal dipole ratio (Ir(mCPDTiq)2tmd, complex 1: 80%, Ir(mCPDTiq)2acac, complex 2: 81%) with a short radiative lifetime (1: 386 ns, 2: 323 ns). The device also shows an extremely low turn-on voltage (Von) of 2.2 V and a high RC of 720 mW/sr/m2/V. The results on the Von and RC of the device is demonstrated an outstanding performance among the Ir(III)-based NIR OLEDs with a similar emission peak. [ABSTRACT FROM AUTHOR]

Recently, as state‐of‐the‐art displays, wearable electronic devices and free‐form displays have begun to attract attention to the point that much research on textile‐based displays has been actively conducted as an ultimate platform for wearable displays. However, although many studies have reported organic light‐emitting diodes (OLEDs) as the most suitable type for textile‐based displays due to their high opto‐electronic performance and flexibility, most research on textile‐based OLEDs (textile OLEDs) has left for the future improvements that require the use of transparent OLEDs (trOLEDs) for applications where aesthetics are important, such as fashion displays and automobile interiors. Herein, RGB‐color trOLEDs are designed using a dielectric‐metal‐dielectric transparent electrode to overcome the limitations of previous works on textile‐based non‐transparent OLEDs and to improve the aesthetic elements of textile displays. The opto‐electronic performance and the mechanical characteristics of textile RGB trOLEDs are analyzed, and specifically, this study suggests a new method and a novel equation for an optical analysis to quantify the clarity of printed color images (i.e., information) on a textile substrate when trOLEDs on the textile substrate are not operated, as needed to optimize and maximize the aesthetic elements of textile displays. [ABSTRACT FROM AUTHOR]

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‐emitting diode (OLED) platform that can move flexibly and conform to the curvature of the human body. The soft and flexible textile‐based blue OLED platform is designed to have a peak wavelength of 470 nm, suitable for jaundice treatment, and shows performance (>20 µW cm−2 nm−1) suitable for intensive jaundice treatment even at low voltage (<4.0 V). The textile‐based OLEDs fabricated in this study exhibit an operating reliability of over 100 h and low‐temperature operation (<35 °C). The results of an in vitro jaundice treatment test using a large‐area blue OLED confirm that the bilirubin level decreases to 12 mg dL−1 with 3 h of OLED irradiation. [ABSTRACT FROM AUTHOR]

Smart displays have been integrated into our daily life, providing new concepts of interconnections between humans and interactivity with close collaboration between users. As a centerpiece of this integration, textile displays that can be worn like clothes are being intensively developed and are poised to provide a more intimate and closer connection. Among various light sources that have been used in the field of textile displays, organic light‐emitting diodes (OLEDs) have attracted considerable attention as one of the promising candidates for realizing truly wearable textile displays (i.e., wearing displays) in that they have shown the highest level of technical maturity, including high optoelectronic performance and flexibility, which can provide not only clear visual information and versatility regardless of the surrounding environment but have also been industrially proven. This review introduces the recent progress in OLED‐based textile displays and related technologies, with the discussion of challenges and limitations of the fiber‐ and fabric‐based approaches. Additionally, specific opinions are provided on research opportunities for organic light‐emitting textile displays, which can contribute to realizing truly wearable textile displays with a complete platform in the future. [ABSTRACT FROM AUTHOR]

Long wavelengths that can deeply penetrate into human skin are required to maximize therapeutic effects. Hence, various studies on near-infrared organic light-emitting diodes (NIR OLEDs) have been conducted, and they have been applied in numerous fields. This paper presents a microcavity tandem NIR OLED with narrow full-width half-maximum (FWHM) (34 nm), high radiant emittance (> 5 mW/cm2) and external quantum efficiency (EQE) (19.17%). Only a few papers have reported on biomedical applications using the entire wavelength range of the visible and NIR regions. In particular, no biomedical application studies have been reported in the full wavelength region using OLEDs. Therefore, it is worth researching the therapeutic effects of using OLED, a next-generation light source, and analyzing trends for cell proliferation effects. Cell proliferation effects were observed in certain wavelength regions when B, G, R, and NIR OLEDs were used to irradiate human fibroblasts. The results of an in-vitro experiment indicated that the overall tendency of wavelengths is similar to that of the cytochrome c oxidase absorption spectrum of human fibroblasts. This is the first paper to report trends in the cell proliferation effects in all wavelength regions using OLEDs. [ABSTRACT FROM AUTHOR]

We demonstrate color‐tunable organic light‐emitting diodes (OLEDs) with a red, green, and blue emission material deposited on an ultra‐thin textile platform. It secures similar performance to glass‐based OLEDs and proves the potential of a true wearable fashion display. [ABSTRACT FROM AUTHOR]

High‐performance fiber‐based red OLEDs and TFTs for high‐quality visualization systems and bio/medical applications based on full comprehension of cylindrical fiber and device structures are suggested. These wearable devices provide a foundation for realizing fiber‐based complete textile displays and their use in bio/medical applications. [ABSTRACT FROM AUTHOR]

Wearable electronic devices are being developed because of their wide potential applications and user convenience. Among them, wearable organic light emitting diodes (OLEDs) play an important role in visualizing the data signal processed in wearable electronics to humans. In this study, textile-based OLEDs were fabricated and their practical utility was demonstrated. The textile-based OLEDs exhibited a stable operating lifetime under ambient conditions, enough mechanical durability to endure the deformation by the movement of humans, and washability for maintaining its optoelectronic properties even in water condition such as rain, sweat, or washing. In this study, the main technology used to realize this textile-based OLED was multi-functional near-room-temperature encapsulation. The outstanding impermeability of TiO2 film deposited at near-room-temperature was demonstrated. The internal residual stress in the encapsulation layer was controlled, and the device was capped by highly cross-linked hydrophobic polymer film, providing a highly impermeable, mechanically flexible, and waterproof encapsulation. [ABSTRACT FROM AUTHOR]

We demonstrated stretchable OLEDs on patterned substrate by relieving stress through the substrates during stretching states. First, we demonstrated OLEDs with stress‐relief substrates composed of pillar structures and patterned substrate and it exhibited stable performance. We analyzed the role of the pillars with a mechanical simulation tool. Furthermore, we proposed new serpentine bridge structure by designing rotational plate to reduce stress onto the bridges. [ABSTRACT FROM AUTHOR]

We demonstrate a very thin flexible OLED‐based photonic skin with a total thickness of 6 microns for application in attachable phototherapeutics. By controlling the peak wavelengths (600‐700nm) and irradiation interval of the flexible OLED, it was optimized, improving the regeneration effect of artificial skin by up to 70%. [ABSTRACT FROM AUTHOR]

Phototherapeutics is both safely noninvasive and can be employed to treat a variety of sites and diseases. Current rigid and bulky conventional light sources, such as LED or laser‐based phototherapy devices, are difficult to transport and use for regular irradiation treatments. To solve this problem, flexible organic light‐emitting diode (OLED) light sources are the best candidates, and if applied very thinly as a skin‐like platform, the ultimate attachable phototherapeutics can be realized. We demonstrated a very thin flexible OLED‐based photonic skin with a total thickness of 6 μm for application in attachable phototherapeutics. It was optimized by controlling the peak wavelengths (600–700 nm) and irradiation interval of the flexible OLED thus improving the regeneration effect of the artificial skin by up to 70%. In addition, when the flexible OLED‐based photonic skin was attached to a dressing film before being applied to the skin, it delivered the same electro‐optical properties, while protecting against external contamination. The OLED skin on the dressing film had an operating lifetime of more than 100 h. These results confirmed the applicability of flexible OLED‐based photonic skin to various light treatment areas, such as surgical wounds that require periodic irradiation. [ABSTRACT FROM AUTHOR]

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 addressed. This review covers the recent developments in encapsulation technologies, particularly their material and structural designs, for highly reliable, flexible OLEDs. The solution concepts for the existing technical hurdles in flexible encapsulations are addressed. Among the various advanced flexible encapsulation technologies developed so far, neutral-axis engineering with a thin metal layer and a crack arrester is introduced. [ABSTRACT FROM AUTHOR]

In this study, we show that it is possible to fabricate phosphorescent organic light‐emitting diodes (phOLEDs) on a flexible fiber substrate. We believe that this approach provides a way to overcome the problem of an insufficient efficiency that most fiber‐based light‐emitting devices have so far. [ABSTRACT FROM AUTHOR]

We demonstrate a wearable photobiomodulation patch using attachable flexible organic light‐emitting diodes. These platforms are very thin (~1.1mm) and can be attached to any part of the body. In addition, by controlling the wavelength (630nm to 650nm), the keratinocyte wound‐healing promotion effect can be optimized by as much as 31.5%. [ABSTRACT FROM AUTHOR]

Organic light-emitting diodes (OLEDs) are remarkably promising display devices that can function in mechanically flexible configurations on a plastic substrate due to various compelling properties, including organic constituents, ultrathin and simple structure, and low-temperature fabrication. In spite of successful demonstrations of flexible OLEDs, some technical issues of containing relatively thick transparent electrodes made of ceramic materials and an unstable flexible encapsulation system have impeded reaching high levels of reliability and durability toward full commercialization. This review covers recent developments in structure designs for highly durable flexible OLEDs, ranging from alternative transparent electrodes to thin-film encapsulation layers, in which solution concepts for the existing critical issues of flexible OLEDs are addressed. Emerging unusual substrates and their application strategies are additionally introduced to find intimations of future display technologies and hence to disclose nonclassic flexible OLEDs. [ABSTRACT FROM AUTHOR]

A zero-stress thin-film encapsulation method was developed to mitigate residual stress. By keeping total residual stress at a minimum, the intrinsic mechanical stability of the encapsulated device was increased. The lifetimes of FOLEDs using the zero-stress encapsulation method were increased by more than 35% compared with conventional encapsulation. [ABSTRACT FROM AUTHOR]

In this study, two types of PLEDs were utilized for an in‐vitro test to verify the effect of solution‐processed OLEDs on cell metabolic activity. As a result, there was no cytotoxicity on any of the irradiated fibroblast cells, and an improved cell proliferation effect of about 109% was obtained. [ABSTRACT FROM AUTHOR]

The article looks at a study which demonstrate actual fabric based organic light-emitting diode (OLED) which have been encapsulated in such multilayer barrier films. It mentions fabrication process for polyurethane (PU) planarization, and insert multilayer capping films to improve the reliability of the OLEDs. It also mentions encapsulation against oxygen and moisture, the reliability of OLED devices is affected by the surface roughness of the substrates.

The resonance effect between the localized surface plasmon mode and the excited excitons in organic materials can enhance the optical and electrical performances of organic light-emitting diodes (OLEDs). Here, we show an enhancement in the luminescence efficiency of a green OLED by employing silver nanoparticles without an optical microcavity effect. The enhanced photoluminescence and exciton decay rate support the idea that the improved luminescence efficiency is due to the increased spontaneous emission rate of the emitter. Our results indicate that the plasmonic near-field interaction of the light-matter can be a strong engineering tool for high-efficiency organic optoelectronic devices in the display industry. [ABSTRACT FROM PUBLISHER]

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)/MoO3 (5 nm)] and [ZnS (3 nm)/Cs2CO3 (1 nm)/Ag (8 nm)/ZnS (22 nm)], as anode and cathode, respectively. The optimized TFOLED design is fabricated on a polyethylene terephthalate (PET) substrate, and the device shows high transmittance (74.22% around 550 nm) although the PET substrate has lower transmittance than glass. The TFOLEDs operate normally under compressive stress; degradation of electrical characteristics is not observed, comparable to conventional OLEDs with ITO and Al as electrodes. In addition, because the fabricated TFOLEDs show a nearly Lambertian emission pattern and a negligible shift of Commission International de l'Eclairage (CIE) coordination, it is concluded that the fabricated TFOLEDs are suitable for use in displays. [ABSTRACT FROM AUTHOR]

A clothing‐shaped substrate that matches the characteristics of a fabric was designed to minimize the physical strain and stress on organic light‐emitting diodes(OLEDs).The room temperature process minimized the deformation of the fabric during the fabrication process, and a clothing‐shaped substrate having the same surface as a flat glass substrate was fabricated. Finally, clothing‐shaped OLED that provide excellent wearing comfort such as clothes was proposed, and flexibility, bending and wrinkling characteristics were evaluated. [ABSTRACT FROM AUTHOR]

We suggest organic light emitting diodes (OLEDs) fabricated on textile substrates. 3.5 dyads of an aluminum oxide (Al2O3) - poly(vinyl alcohol) (PVA) multilayer were used for planarization and encapsulation. The fabricated device showed similar performances and cell images after 400 h in ambient air. [ABSTRACT FROM AUTHOR]

We investigated the optical properties of a dielectric-metal-dielectric (DMD) electrode in relation to the surface morphology of Ag. We intentionally modified the number of voids and the surface coverage of the Ag layer. Normal and oblique incident configurations for transmittance measurement were employed to establish the relations between the Ag morphology and optical transmittance of the DMD electrode. For the configuration of MoO3{\rm/Ag/MoO}3 (MAM), variation in the surface morphology of the Ag minimized the light scattering loss and the absorption of photons. This could lead to 18.6% enhancement of the transmittance at \lambda=550~nm. The optical out-coupling was also enhanced in OLEDs, which was based on the MAM anode incorporating the continuous Ag film. [ABSTRACT FROM AUTHOR]

Clothing‐type, textile‐based OLEDs and their bio‐medical application have been investigated. Textile‐based OLEDs have shown wide applicability and washability as well as high flexibility for a wearing textile displays. Furthermore, a novel phototherapy for neonatal jaundice by using textile‐OLEDs was proposed in this work. [ABSTRACT FROM AUTHOR]

We fabricated OLEDs with a micro patterned flexible transparent conductive polymer electrode by the mold transfer process (MTP). For the polymer anode, the electrical properties of PEDOT:PSS can be enhanced by adding additives in order to improve its conductivity and make it possible to control the surface energy of the substrate for the MTP. This process allows the successful fabrication of mold transfer processed OLEDs by using patterned conductive polymer anodes without indium tin oxide (ITO). [ABSTRACT FROM AUTHOR]

We propose a nanostructured blue organic light-emitting diode (OLED) with a perforated WO3 hole injection layer that improves the outcoupling efficiency of blue OLEDs by the extraction of trapped surface plasmon polaritons and wave guide modes. [ABSTRACT FROM AUTHOR]

We verified the possibility of the use of graphene oxide (GO) as a hole-injecting material for organic light-emitting diodes (OLEDs). The performance of OLEDs with a GO hole-injection layer (HIL) is comparable to that of conventional devices with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) HIL. We expect that GO can resolve the intrinsic problems of the common solution-processable HIL material, PEDOT:PSS. [ABSTRACT FROM AUTHOR]

Abstract: Transparent electrodes cannot easily be created with high transmittance and low sheet resistance simultaneously, although some optoelectronic devices, such as large organic light-emitting diode (OLED) displays and lightings, require very low resistive transparent electrodes. Here, we propose a very low resistive transparent electrode (∼1.6Ω/sq) with a high transmittance (∼75%) for OLED devices, the transmittance level of which represents the highest reported value to date given such a low sheet resistance level. It consists of a stacked silver (Ag)/zinc oxide (ZnO)/Ag multilayer covered by high refractive index dielectric layers. The proposed multilayer electrode with optimal layer thicknesses has a high and wide spectral transmittance peak due to interference. The low sheet resistance is a result of two Ag layers connected via the sandwiched ZnO layer. In addition to its low sheet resistance coupled with high transmittance, the proposed multilayer electrode has good flexibility. An OLED with an anode of the stacked Ag/ZnO/Ag multilayer shows performance comparable to that of an anode of indium tin oxide. [Copyright &y& Elsevier]

Herein, a novel thin-film encapsulation for flexible organic light-emitting diodes (FOLEDs) is proposed, and its long-term reliability in tensile stress conditions was tested. The hybrid nano-stratified moisture barrier consists of 2.5 dyads of an Al 2 O 3 /ZnO nano-stratified structure and a S-H nanocomposite organic layer. The nano-stratified structure is prepared by low-temperature atomic layer deposition and the S-H nanocomposite by spin-coating at a thickness of 30 and 120 nm, respectively. An optical transmittance of 89.05% was measured with the 2.5-dyad hybrid nano-stratified moisture barrier with a total thickness of 330 nm. A low water vapor transmission rate (WVTR) of 1.91 × 10 −5 g/m 2 day was recorded based on an electrical Ca test at 30 °C and 90% R.H. without losing its properties after a bending test. With this highly reliable hybrid nano-stratified moisture barrier, FOLEDs were successfully encapsulated. After 30 days under conditions of 30 °C and 90% R.H. with tensile stress, the J-V-L performances of the FOLEDs were comparable to those of the initial state without dark spots. These results suggest that this hybrid nano-stratified moisture barrier is an excellent method for encapsulating FOLEDs. [ABSTRACT FROM AUTHOR]

Here we implement a systematic investigation of two-dimensional silver nanomeshes (AgNMs) for large-area, very low-resistive transparent electrodes and their successful application to ITO-free organic light-emitting diodes (OLEDs). Experimental results, as well as theoretical analyses with optical and electrical calculation, show that an optimized AgNM electrode fabricated via cost-effective colloidal lithography can have high transmittance and low sheet resistance simultaneously. By using an index-matching concept for further improvement of optical performance, highly transparent AgNM electrodes are achieved at very low sheet resistance (∼3.5 Ω/sq). Based on the study regarding transmittance variation of AgNM electrodes embedded in OLEDs, a pertinent index-matching layer is proposed for high performance AgNM-based OLEDs. [ABSTRACT FROM AUTHOR]

Organic light-emitting diodes (OLEDs) typically have low out-coupling efficiency. In this paper, a solution-based nanoparticle layer is presented as a nanostructure to enhance the out-coupling efficiency of OLEDs. Silica nanoparticles (NPs) are randomly distributed on indium tin oxide by spin-coating a silica NP solution. By further spin-coating poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as a hole injection layer, a randomly corrugated PEDOT:PSS layer is fabricated. A nanostructured OLED having the corrugated PEDOT:PSS layer above the NP layer shows enhanced external quantum efficiency and power efficiency because the trapped light of the waveguide and surface plasmon modes is extracted by Bragg diffraction. The nanostructured OLED shows no angular dependence due to the broad periodicities of the corrugation. The simply fabricated and cost-effective silica NP layer nanostructure, which does not require a lithography step, has potential to enhance the efficiency of both white OLED displays and lighting. [ABSTRACT FROM AUTHOR]

We investigated the highly flexible, transparent and very low resistance ZnS/1st Ag/ZnO/2nd Ag/WO 3 (ZAZAW) multilayer electrodes on PET substrate as an anode in flexible organic light-emitting diodes (OLEDs). A theoretical calculation was first conducted to obtain the optimal thickness of the ZAZAW multilayer for high transparency. Its measured luminous transmittance was over 80% in the visible range with a very low sheet resistance of 2.17 Ω/sq., and it had good mechanical flexibility due to the ductility of Ag. Ag’s effect on optical and electrical properties was also studied. Flexible OLEDs devices that were fabricated on ZAZAW multilayer anode showed good hole injection properties comparable to those of ITO-based OLEDs due to the use of WO 3 as a hole injection layer. However, the electroluminescent properties of the ZAZAW-based OLEDs varied depending on WO 3 thickness. Although the transmittance of the ZAZAW electrode was reduced by tuning the WO 3 thickness to adjust the microcavity effect, the device efficiency could be enhanced above that of ITO-based OLEDs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Phosphorescent TrOLEDs have perforated WO3 layer to enhance outcoupling efficiency. [•] Nanostructured TrOLEDs have higher EQE values compared to the conventional TrOLEDs. [•] The values were 28% and 33% higher for bottom and top emission, respectively. [•] The extraction of trapped surface plasmon mode was the main reason for enhancement. [•] The nanostructured TrOLEDs showed optical clarity without haziness. [Copyright &y& Elsevier]

Highlights: [•] Quantitative analysis of electrical property in nanostructure embedded OLEDs are investigated. [•] Two geometric factors are suggested which influence the operating voltage. [•] Effective length is determined by thickness ratio of nanostructure and organic layer. [•] Effective area is determined by periodicity of nanostructure. [ABSTRACT FROM AUTHOR]

Highlights: [•] The characteristics of multi-layer electrode (ZnS/Ag/MoO3) was investigated. [•] The quasi-perfect Ag film of 7-nm thickness was first observed on the ZnS layer. [•] The structure of ZnS(25nm)/Ag(7nm)/MoO3(5nm) was proposed through FDTD calculations. [•] The transmittance of 83% and the sheet resistance of 9.6Ohm/sq were recorded. [•] The Z25A7M5-based FOLED showed practical I–V–L characteristics. [Copyright &y& Elsevier]

Highlights: [•] We reported the first OLEDs on actual soft fabrics that can be used for a wearable display. [•] PU and PVA layers were used for planarization to ensure the stable operation of OLEDs. [•] Planarization layers slightly degrade the deformability and breathability of bare fabrics. [•] The fabricated sample showed a high current efficiency of around 8cd/A. [•] The fabricated sample showed reliability during a 1000 cycle bending test (R =5mm). [ABSTRACT FROM AUTHOR]

Highlights: [•] We developed a thin film encapsulation method using MgO deposited by an ALD system and S-H nano-composite. [•] Barrier performance of thin film encapsulation is comparable to that of glass-lid encapsulation. [•] The multi-barrier had a high transmittance. [•] The thin film encapsulation process can be applied to OLED devices without degradation or dark spots. [•] The luminance degradation of the thin film encapsulated OLED was identical to that of the glass-lid encapsulation. [ABSTRACT FROM AUTHOR]