Search

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]

Herein, we develop a novel all-in-one cathode-separator-anode monolith architecture designed for high-capacity, ultra-thin flexible batteries. This architecture involves directly casting electrode slurry onto both sides of a polypropylene (PP) separator. Controlled volatility and wettability of the solvent system are critical for the formation of neat electrode coating layers on the PP separator. The monolith structure offers remarkable flexibility and intimate contact between the electrode and separator, which is especially advantageous when stacked for higher areal capacity. The monoliths are conjoined into an all-in-one multi-layered monolith structure, deploying electrode slurry as an 'electrochemically active adhesive' between them, enabling the creation of high-capacity, ultra-thin flexible batteries. The resulting pouch cell exhibits a high capacity of 44.5 mA h (areal capacity of 4.9 mA h cm−2) at 1 mA and a thickness below 1 mm. Notably, this cell boasts superior rate capability even at this high capacity, showing a discharge capacity of 36.3 mA h at 20 mA. Practical application of this high-capacity, ultra-thin flexible battery is demonstrated in a band-type light-therapy patch, which shows operational stability when bent around a human arm. This development marks a significant advancement in the design of ultra-thin, high-capacity flexible batteries, with potential applications in flexible and wearable battery technologies. [ABSTRACT FROM AUTHOR]

Integrating organic light-emitting diodes (OLEDs) with light therapy can significantly advance biomedical applications by offering non-invasive, precise, and customizable treatments. Developing innovative device designs and performing cellular tests is essential to assess the safety and effect of OLED-based light therapies in dermatology. As such, a wearable OLED medical device prototype has been created for easy attachment to the body, ensuring consistent exposure to skin injuries due to its comfortable fit and user-friendly operation. Moreover, it has demonstrated effectiveness in enhancing wound healing, as indicated by a max 23% increase in fibroblast proliferation at the cellular level. [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]

This study explores Thin Film Encapsulation, highlighting its impressive resistance to crack propagation achieved by intentionally introducing defects between two distinct inorganic materials. Through strategic interface defect engineering, we have successfully reinforced the encapsulation's robustness, contributing to its enhanced performance and durability. [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 study introduces a simplified fabrication method for implementing a TFT array on a cylindrical fiber, using only four masks and a low‐temperature process below 120 ℃. To overcome the limitations of the one‐dimensional cylindrical fiber structure, the study emphasizes the design and implementation of a three‐dimensional backplane, utilizing the side or bottom surfaces of the fiber to address patterning and shadowing challenges. The proposed TFTs, part of the 2T1C pixel circuit within the fiber, exhibit electrical properties suitable for driving OLEDs. [ABSTRACT FROM AUTHOR]

Laser lift-off (LLO) of ultrathin polyimide (PI) films is important in the manufacturing of ultrathin displays. However, conventional LLO technologies face challenges in separating the ultrathin PI films without causing mechanical and electrical damage to integrated devices. Here, we propose a graphene-enabled laser lift-off (GLLO) method to address the challenges. The GLLO method is developed by integrating chemical vapor deposition (CVD)-grown graphene at the interface between a transparent carrier and an ultrathin PI film, exhibiting improved processability and lift-off quality. In particular, the GLLO method significantly mitigates plastic deformation of the PI film and minimizes carbonaceous residues remaining on the carrier. The role of graphene is attributed to three factors: enhancement of interfacial UV absorption, lateral heat diffusion, and adhesion reduction, and experimentations and numerical simulations verify the mechanism. Finally, it is demonstrated that the GLLO method separates ultrathin organic light-emitting diode (OLED) devices without compromising performance. We believe that this work will pave the way for utilizing CVD graphene in various laser-based manufacturing applications., (© 2024. The Author(s).)