IT Home reported on January 15th that a team from Seoul National University in South Korea and Drexel University in the United States announced the development of a new type of OLED panel that combines flexibility and elasticity, achieving a breakthrough in stretchability and brightness retention. The research results were published yesterday in the journal *Nature*.

Traditional flexible OLEDs are typically built on a bendable plastic substrate, allowing them to operate in bent, rolled, or even folded states. This technology dates back to the 1990s and gained widespread attention in the 2010s with the introduction of curved and flexible screen phones by manufacturers such as Samsung. However, with prolonged use, repeated bending can damage the electrodes and organic layers, leading to a decrease in brightness and flexibility.

This new OLED panel uses a flexible phosphorescent polymer light-emitting layer, combined with transparent electrodes made of MXene nanomaterials, allowing the device to maintain most of its brightness output even when stretched to 1.6 times its original length.

The research team pointed out that traditional methods often improve flexibility by introducing stretchable but insulating polymers, which can actually hinder charge transport and reduce luminous efficiency. Furthermore, commonly used electrode materials tend to become brittle or even break after repeated stretching. To address this, the researchers employed a stretchable contact electrode based on MXene. This electrode possesses higher mechanical strength, and its tunable work function helps improve the injection efficiency of holes or electrons, fundamentally improving device performance.

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Regarding luminescent materials, the team redesigned the core luminescent layer, using a novel organic material called "exciton complex-assisted phosphorescence layer" (ExciPh). This material itself has good stretchability, and through chemical design, the charge level structure was optimized, allowing more charges to combine and form excitons, thus significantly improving luminous efficiency. Experimental data show that over 57% of the excitons in the ExciPh luminescent layer can be converted into visible light, while the conversion rate of common OLED polymer luminescent layers is typically only 12%–22%. Furthermore, the researchers embedded the ExciPh layer within a thermoplastic polyurethane elastomer matrix and optimized the electrode structure to improve charge distribution efficiency and overall flexibility within the device.

In electrode design, the team combined MXene, a two-dimensional nanomaterial developed by Drexel University in 2011, with silver nanowires to construct a transparent and stretchable conductive network. This structure not only possesses excellent conductivity but also maintains stable charge injection capability during repeated stretching and bending, allowing the OLED to retain high brightness even under deformation. The researchers stated that MXene's layered structure and high conductivity make it an ideal choice for flexible OLED electrode materials.

In the experimental verification phase, the research team fabricated heart-shaped and number-shaped green flexible OLED display samples and systematically tested their luminous efficiency and durability under stretching conditions. The results showed that when the device was stretched to 60% of its maximum strain, its performance decreased by only about 10.6%; after 100 repeated stretching cycles under a 2% strain condition, it still maintained about 83% of its initial brightness, demonstrating significantly better overall performance than previous similar solutions.

Researchers believe that this new OLED panel will lay the foundation for next-generation wearable and deformable display devices and play an important role in real-time health monitoring and wearable communication. In the future, the team plans to further explore more flexible substrate materials, finely control the organic light-emitting layer to achieve different color and brightness performances, and simplify the manufacturing process to promote the large-scale application of stretchable OLED technology.