Organic Light–Emitting Diodes In article number 2310268, Heonsu Jeon, Jeong Hyun Kwon, and co-workers customize a multifunctional hazy polymer substrate for extreme environments using a simple ion-beam treatment and functional barrier film to realize highly reliable next-generation displays. By using the developed multifunctional substrate, highly efficient and reliable wearable organic light-emitting diodes applicable in various fields are realized by improving their efficiency and environmental reliability.

Abstract Thin‐film encapsulation is a core technology that determines the reliability of next‐generation displays, including wearable and stretchable displays. However, the encapsulation technologies developed to date are highly vulnerable to mechanical stress and harsh hygrothermal environments. Therefore, the degradation of their original encapsulation performance (as determined by mechanical and environmental reliability tests) is a major limitation. This paper describes a novel inorganic/organic multibarrier encapsulation method based on structural and material design to overcome the reliability problems of freeform displays. The highly reliable mechanical properties of the encapsulation system are verified using the tensile‐testing‐on‐water method, which is the most reliable method for thin films with thicknesses of tens to hundreds of nanometers. The optimal encapsulation system developed herein achieves an unprecedented elongation of 2.8% in its freestanding form, surpassing the elastic limit of traditional inorganic materials, and maintains a notable elongation of 1.43% after being exposed to harsh environments for 30 h (85 °C and 85% relative humidity). The inorganic/organic hybrid encapsulation system designed through systematic analysis in this study is expected to increase the lifetime of devices and facilitate high outdoor usability in applying ultraflexible wearable organic light‐emitting diodes.

Driven by innovations in the form factor of organic light-emitting diode (OLED) displays, the application scope of OLED technology now encompasses the biomedical field, in addition to its existing application domains of mobile phones, televisions, and lighting. This paper introduces an ultrathin, ultraflexible, and high-power bio-OLED patch with perfect waterproofing and an elongation of 2.04% through material and structural design. Furthermore, the OLED patch with a parallel-stacked OLED delivers a high output of 100 mW/cm2, achieves a 40% power density improvement compared to glass-based OLEDs using optimized encapsulation, and is suitable for photodynamic therapy owing to its lifetime of 183 h at an intensity of 35 mW/cm2. Since OLED patches are required for long-term stable operation in various biomedical applications, we developed an OLED patch with an outcoupling structure using a simple method. The improved OLED patch achieved a 35% increase in light extraction compared to the original OLED patch.

Stretchable displays represent a critical advancement in next-generation wearable devices, attracting attention for their potential to address numerous challenges. This study introduces a novel stretching approach for stretchable devices through a rotational membrane design. Patterned substrates offer significant advantages in process compatibility and device performance among various fabrication methods. The rotational patterned substrate easily enables structural modifications, while vacuum deposition facilitates precise deposition of thin-film encapsulations and organic light-emitting diode (OLED) layers. The resulting stretchable OLED (SOLED) with optimized Al₂O₃/SiO₂ nanolaminate/parylene-C-based multibarrier encapsulation demonstrates comparable luminance, current density, and operational lifespan to glass-based OLED devices. The innovative membrane rotation technique evenly distributes stress across the substrate, ensuring stability under high-strain conditions. Notably, the structure remained stable under a strain of 60%, exceeding twice the strain tolerance of previous designs. This approach addresses the strain fill-factor limitations observed in prior studies, achieving sufficient strain capacity for high-density displays. Consequently, SOLEDs with high fill-factors minimize non-emissive circuit areas, paving the way for high-luminance, reliable, and stretchable displays tailored for next-generation wearable technologies.

Psoriasis is a chronic inflammatory skin disease that significantly affects the quality of life of patients. Photodynamic therapy is effective in treating psoriasis; however, existing light sources, such as lasers and light-emitting diodes (LEDs), have limitations in terms of flexibility, uniformity of light irradiation, and patient convenience. In this study, a high-power ultraflexible organic LED (OLED) patch is fabricated on a PET adhesive film, resulting in a high output of 60 mW cm^-2 at 7.5 V. Based on high-performance encapsulation technology, the OLED patch achieved a lifetime of 177 h and no performance change after bending for 10 000 times for a radius of 2 mm at 35 mW cm^-2. Finally, photodynamic therapy is performed in a psoriasis mouse model using an OLED for the first time, and the effect is confirmed through a cross-sectional analysis of the mouse skin, in which the thickness of the diseased area is reduced by 66% compared with the control group.

Numerous studies have aimed to improve the mechanical flexibility of thin-film encapsulation, a key obstacle in commercializing wearable organic light-emitting diodes (OLEDs). This study develops a silbione-blended organic/inorganic hybrid epoxy polymer (hybrimer) with high toughness as an organic barrier to enhance the flexibility of organic-inorganic multi-barriers. The optimal silbione-blended hybrimer (SBH) films exhibit superior mechanical properties, including increased elongation and tensile strength, compared to the hybrimer. The 3.5-dyad SBH-based encapsulation achieves a water vapor transmission rate of 7.83 × 10−6 g/m2/day and 9.45 × 10−5 g/m2/day before and after bending at a strain of 2%, respectively. In addition, the SBH barrier effectively protects the inorganic barrier by forming a robust aluminate phase at the interface between the inorganic and organic barrier, even under harsh conditions of 85 °C/85% relative humidity, demonstrating its potential for wearable applications. As a result, SBH-based encapsulations offer mechanical and environmental stability, making them ideal for wearable OLEDs.

Organic Light–Emitting Diodes In article number 2310268, Heonsu Jeon, Jeong Hyun Kwon, and co-workers customize a multifunctional hazy polymer substrate for extreme environments using a simple ion-beam treatment and functional barrier film to realize highly reliable next-generation displays. By using the developed multifunctional substrate, highly efficient and reliable wearable organic light-emitting diodes applicable in various fields are realized by improving their efficiency and environmental reliability.